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Mwalugelo YA, Mponzi WP, Muyaga LL, Mahenge HH, Katusi GC, Muhonja F, Omondi D, Ochieng AO, Kaindoa EW, Amimo FA. Livestock keeping, mosquitoes and community viewpoints: a mixed methods assessment of relationships between livestock management, malaria vector biting risk and community perspectives in rural Tanzania. Malar J 2024; 23:213. [PMID: 39020392 PMCID: PMC11253484 DOI: 10.1186/s12936-024-05039-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 07/09/2024] [Indexed: 07/19/2024] Open
Abstract
BACKGROUND Livestock keeping is one of the potential factors related to malaria transmission. To date, the impact of livestock keeping on malaria transmission remains inconclusive, as some studies suggest a zooprophylactic effect while others indicate a zoopotentiation effect. This study assessed the impact of livestock management on malaria transmission risks in rural Tanzania. Additionally, the study explored the knowledge and perceptions of residents about the relationships between livestock keeping and malaria transmission risks in a selected village. METHODS In a longitudinal entomological study in Minepa village, South Eastern Tanzania, 40 households were randomly selected (20 with livestock, 20 without). Weekly mosquito collection was performed from January to April 2023. Indoor and outdoor collections used CDC-Light traps, Prokopack aspirators, human-baited double-net traps, and resting buckets. A subsample of mosquitoes was analysed using PCR and ELISA for mosquito species identification and blood meal detection. Livestock's impact on mosquito density was assessed using negative binomial GLMMs. Additionally, in-depth interviews explored community knowledge and perceptions of the relationship between livestock keeping and malaria transmission risks. RESULTS A total of 48,677 female Anopheles mosquitoes were collected. Out of these, 89% were Anopheles gambiae sensu lato (s.l.) while other species were Anopheles funestus s.l., Anopheles pharoensis, Anopheles coustani, and Anopheles squamosus. The findings revealed a statistically significant increase in the overall number of An. gambiae s.l. outdoors (RR = 1.181, 95%CI 1.050-1.862, p = 0.043). Also, there was an increase of the mean number of An. funestus s.l. mosquitoes collected in households with livestock indoors (RR = 2.866, 95%CI: 1.471-5.582, p = 0.002) and outdoors (RR = 1.579,95%CI 1.080-2.865, p = 0.023). The human blood index of Anopheles arabiensis mosquitoes from houses with livestock was less than those without livestock (OR = 0.149, 95%CI 0.110-0.178, p < 0.001). The majority of participants in the in-depth interviews reported a perceived high density of mosquitoes in houses with livestock compared to houses without livestock. CONCLUSION Despite the potential for zooprophylaxis, this study indicates a higher malaria transmission risk in livestock-keeping communities. It is crucial to prioritize and implement targeted interventions to control vector populations within these communities. Furthermore, it is important to enhance community education and awareness regarding covariates such as livestock that influence malaria transmission.
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Affiliation(s)
- Yohana A Mwalugelo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.
- Department of Biomedical Sciences, Jaramogi Oginga Odinga University of Science and Technology, P. O. Box 210, Bondo, 40601, Kenya.
| | - Winifrida P Mponzi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Letus L Muyaga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- School of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Herieth H Mahenge
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- The Nelson Mandela, African Institution of Science and Technology, School of Life Sciences and BioEngineering, Tengeru, Arusha, United Republic of Tanzania
| | - Godfrey C Katusi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Faith Muhonja
- School of Public Health, Amref International University, P.O. Box 27691-00506, Nairobi, Kenya
| | - Dickens Omondi
- Department of Biomedical Sciences, Jaramogi Oginga Odinga University of Science and Technology, P. O. Box 210, Bondo, 40601, Kenya
| | - Alfred O Ochieng
- Department of Biological Sciences, Jaramogi Oginga Odinga University of Science and Technology, P.O. Box 210, Bondo, 40601, Kenya
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- The Nelson Mandela, African Institution of Science and Technology, School of Life Sciences and BioEngineering, Tengeru, Arusha, United Republic of Tanzania
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Fred A Amimo
- Department of Biomedical Sciences, Jaramogi Oginga Odinga University of Science and Technology, P. O. Box 210, Bondo, 40601, Kenya
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Mandai SS, Francis F, Challe DP, Seth MD, Madebe RA, Petro DA, Budodo R, Kisambale AJ, Chacha GA, Moshi R, Mbwambo RB, Pereus D, Bakari C, Aaron S, Mbwambo D, Lusasi A, Kajange S, Lazaro S, Kapologwe N, Mandara CI, Ishengoma DS. High prevalence and risk of malaria among asymptomatic individuals from villages with high prevalence of artemisinin partial resistance in Kyerwa district of Kagera region, north-western Tanzania. Malar J 2024; 23:197. [PMID: 38926854 PMCID: PMC11201325 DOI: 10.1186/s12936-024-05019-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 06/16/2024] [Indexed: 06/28/2024] Open
Abstract
BACKGROUND Although Tanzania adopted and has been implementing effective interventions to control and eventually eliminate malaria, the disease is still a leading public health problem, and the country experiences heterogeneous transmission. Recent studies reported the emergence of parasites with artemisinin partial resistance (ART-R) in Kagera region with high prevalence (> 10.0%) in two districts of Karagwe and Kyerwa. This study assessed the prevalence and predictors/risk of malaria infections among asymptomatic individuals living in a hyperendemic area where ART-R has emerged in Kyerwa District of Kagera region, north-western Tanzania. METHODS This was a community-based cross-sectional survey which was conducted in July and August 2023 and involved individuals aged ≥ 6 months from five villages in Kyerwa district. Demographic, anthropometric, clinical, parasitological, type of house inhabited and socio-economic status (SES) data were collected using electronic capture tools run on Open Data Kit (ODK) software. Predictors/risks of malaria infections were determined by univariate and multivariate logistic regression, and the results were presented as crude (cORs) and adjusted odds ratios (aORs), with 95% confidence intervals (CIs). RESULTS Overall, 4454 individuals were tested using rapid diagnostic tests (RDTs), and 1979 (44.4%) had positive results. The prevalence of malaria infections ranged from 14.4% to 68.5% and varied significantly among the villages (p < 0.001). The prevalence and odds of infections were significantly higher in males (aOR = 1.28, 95% CI 1.08 -1.51, p = 0.003), school children (aged 5-≤10 years (aOR = 3.88, 95% CI 3.07-4.91, p < 0.001) and 10-≤15 years (aOR = 4.06, 95% CI 3.22-5.13, p < 0.001)) and among individuals who were not using bed nets (aOR = 1.22, 95% CI 1.03-1.46, p = 0.024). The odds of malaria infections were also higher in individuals with lower SES (aOR = 1.42, 95% CI 1.17-1.72, p < 0.001), and living in houses without windows (aOR = 2.08, 95% CI 1.46-2.96, p < 0.001), partially open (aOR = 1.33, 95% CI 1.11-1.58, p = 0.002) or fully open windows (aOR = 1.30, 95%CI 1.05-1.61, p = 0.015). CONCLUSION The five villages had a high prevalence of malaria infections and heterogeneity at micro-geographic levels. Groups with higher odds of malaria infections included school children, males, and individuals with low SES, living in poorly constructed houses or non-bed net users. These are important baseline data from an area with high prevalence of parasites with ART-R and will be useful in planning interventions for these groups, and in future studies to monitor the trends and potential spread of such parasites, and in designing a response to ART-R.
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Affiliation(s)
- Salehe S Mandai
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Filbert Francis
- National Institute for Medical Research, Tanga Research Centre, Tanga, Tanzania
| | - Daniel P Challe
- National Institute for Medical Research, Tanga Research Centre, Tanga, Tanzania
| | - Misago D Seth
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Rashid A Madebe
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | | | - Rule Budodo
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | | | - Gervas A Chacha
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Ramadhan Moshi
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Ruth B Mbwambo
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Dativa Pereus
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Catherine Bakari
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | | | | | | | - Stella Kajange
- President's Office, Regional Administration and Local Government, Dodoma, Tanzania
| | - Samuel Lazaro
- National Malaria Control Programme, Dodoma, Tanzania
| | - Ntuli Kapologwe
- Directorate of Preventive Services, Ministry of Health, Dodoma, Tanzania
| | - Celine I Mandara
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Deus S Ishengoma
- National Institute for Medical Research, Dar es Salaam, Tanzania.
- Faculty of Pharmaceutical Sciences, Monash University, Melbourne, Australia.
- Harvard T.H Chan School of Public Health, Harvard University, Boston, MA, USA.
- Department of Biochemistry, Kampala International University in Tanzania, Dar es Salaam, Tanzania.
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Li J, Docile HJ, Fisher D, Pronyuk K, Zhao L. Current Status of Malaria Control and Elimination in Africa: Epidemiology, Diagnosis, Treatment, Progress and Challenges. J Epidemiol Glob Health 2024:10.1007/s44197-024-00228-2. [PMID: 38656731 DOI: 10.1007/s44197-024-00228-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Accepted: 04/10/2024] [Indexed: 04/26/2024] Open
Abstract
The African continent carries the greatest malaria burden in the world. Falciparum malaria especially has long been the leading cause of death in Africa. Climate, economic factors, geographical location, human intervention and unstable security are factors influencing malaria transmission. Due to repeated infections and early interventions, the proportion of clinically atypical malaria or asymptomatic plasmodium carriers has increased significantly, which easily lead to misdiagnosis and missed diagnosis. African countries have made certain progress in malaria control and elimination, including rapid diagnosis of malaria, promotion of mosquito nets and insecticides, intermittent prophylactic treatment in high-risk groups, artemisinin based combination therapies, and the development of vaccines. Between 2000 and 2022, there has been a 40% decrease in malaria incidence and a 60% reduction in mortality rate in the WHO African Region. However, many challenges are emerging in the fight against malaria in Africa, such as climate change, poverty, substandard health services and coverage, increased outdoor transmission and the emergence of new vectors, and the growing threat of resistance to antimalarial drugs and insecticides. Joint prevention and treatment, identifying molecular determinants of resistance, new drug development, expanding seasonal malaria chemo-prevention intervention population, and promoting the vaccination of RTS, S/AS01 and R21/Matrix-M may help to solve the dilemma. China's experience in eliminating malaria is conducive to Africa's malaria prevention and control, and China-Africa cooperation needs to be constantly deepened and advanced. Our review aims to help the global public develop a comprehensive understanding of malaria in Africa, thereby contributing to malaria control and elimination.
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Affiliation(s)
- Jiahuan Li
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Haragakiza Jean Docile
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - David Fisher
- Department of Medical Biosciences, Faculty of Natural Sciences, University of The Western Cape, Cape Town, South Africa
| | - Khrystyna Pronyuk
- Department of Infectious Diseases, O. Bogomolets National Medical University, Kyiv, Ukraine
| | - Lei Zhao
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
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Debebe Y, Tekie H, Dugassa S, Hopkins RJ, Hill SR, Ignell R. Mosquito odour-baited mass trapping reduced malaria transmission intensity: a result from a controlled before-and-after intervention study. BMC Med 2024; 22:41. [PMID: 38281908 PMCID: PMC10823605 DOI: 10.1186/s12916-024-03255-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 01/11/2024] [Indexed: 01/30/2024] Open
Abstract
BACKGROUND Conventional vector control strategies have significantly reduced the malaria burden. The sustainability of these methods is currently challenged. Odour-based traps are emerging technologies that can complement the existing tools. Implementation of odour-based traps for mass trapping is limited due to the restricted range of vectors caught with available carbon dioxide-dependent lures, and the lack of comprehensive field studies. The objective of this study was to assess the impact of odour-mediated mass trapping targeting outdoor vectors, using a synthetic cattle urine lure that attracts a wide range of vector species in a variety of physiological states, on malaria prevalence and entomological parameters to determine malaria transmission intensities. METHODS A controlled before-and-after study was conducted in two rural communities in southern Ethiopia. Baseline monthly entomological and seasonal cross-sectional malaria prevalence surveys were conducted in both communities for a year. Then, mass trapping of mosquitoes was conducted in one of the villages, while the monthly entomological surveillance and seasonal malaria prevalence surveys continued in both villages. Generalised linear mixed models were constructed and tested to determine which factors were significantly affected by the intervention. RESULTS Mass trapping contributed to the reduction of the population of the principal malaria vector, Anopheles arabiensis, and the associated entomological indicators, the human bite rate (HBR) and the entomological inoculation rate (EIR), in the intervention village compared to the control village. The intervention village had an average HBR by An. arabiensis of 3.0 (95% CI 1.4-4.6) during the peak malaria transmission season, compared to 10.5 (95% CI - 0.5-21.5; P < 0.0001) in the control village. The intervention village (mean 0.02, 95% CI - 0.05-0.4.8) had a daily EIR eight times lower than the control village (mean 0.17, 95% CI), which likely contributed to the reduced malaria prevalence in the intervention community following its introduction by ca. 60% (95% CI 55-63). CONCLUSIONS The combined use of odour-based mass trapping and conventional control strategies coincided with a reduction of human-vector contact and malaria prevalence, providing support for odour-baited technologies as a viable option for next-generation vector control tools. Further cluster-randomised control studies are recommended in different eco-epidemiological settings with varying malaria transmission intensities.
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Affiliation(s)
- Yared Debebe
- Department of Zoological Sciences, Addis Ababa University, Addis Ababa, Ethiopia
- Public Health Entomology Research Team, Ethiopian Public Health Institute, Addis Ababa, Ethiopia
- Disease Vector Group, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Habte Tekie
- Department of Zoological Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Sisay Dugassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | | | - Sharon Rose Hill
- Disease Vector Group, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Rickard Ignell
- Disease Vector Group, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.
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Mponzi WP, Msaky DS, Binyaruka P, Kaindoa EW. Exploring the potential of village community banking as a community-based financing system for house improvements and malaria vector control in rural Tanzania. PLOS GLOBAL PUBLIC HEALTH 2023; 3:e0002395. [PMID: 37922222 PMCID: PMC10624283 DOI: 10.1371/journal.pgph.0002395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 10/09/2023] [Indexed: 11/05/2023]
Abstract
House improvement is associated with remarkable reductions in indoor mosquito bites and disease incidences, even in typical rural houses. However, its exploitation remains extremely poor in Tanzania and other endemic countries due to limited financial resources. Nevertheless, village community banks (VICOBA), practiced in Tanzania for nearly two decades, have proven to provide financial services to rural communities that would otherwise not be able to get them from formal financial institutions. This study explored the need, opinion, and willingness of VICOBA members to use VICOBA platforms as a source of finance for improving local houses and eventually controlling mosquito-borne diseases. A mixed-methods approach was used in this study, whereby a survey was administered to 150 participants and twelve focus group discussions were done in three villages in Ulanga district, rural Tanzania. The FGDs comprised eight participants each, with equal representation of males and females. The FGD guide was used to probe the opinions of study participants on malaria transmission, housing condition improvements, and financial resources. About 99% of all participants indicated the urgent need to improve their houses to prevent mosquito bites and were willing to utilize VICOBA for improving their houses. In the focus group discussion, the majority of people who participated were also in need of improving their houses. All participants confirmed that they were at the highest risk of getting mosquito-borne diseases, and they were willing to use money that was either saved or borrowed from their VICOBA for housing improvements and vector control. A self-sustaining financial system destined for house improvement and related interventions against malaria and other mosquito-borne diseases is crucial. The community members were willing to use VICOBA as a source of finance for house improvement and disease control; however, there was limited knowledge and sensitization on how they could utilize VICOBA for disease control.
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Affiliation(s)
- Winifrida P. Mponzi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Dickson S. Msaky
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- The Nelson Mandela, African Institution of Science and Technology, School of Life Sciences and Bio Engineering, Tengeru, Arusha, United Republic of Tanzania
| | - Peter Binyaruka
- Department of Health System, Impact Evaluation and Policy, Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Emmanuel W. Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- The Nelson Mandela, African Institution of Science and Technology, School of Life Sciences and Bio Engineering, Tengeru, Arusha, United Republic of Tanzania
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
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Mmbaga AT, Lwetoijera DW. Current and future opportunities of autodissemination of pyriproxyfen approach for malaria vector control in urban and rural Africa. Wellcome Open Res 2023; 8:119. [PMID: 37440995 PMCID: PMC10333782 DOI: 10.12688/wellcomeopenres.19131.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/23/2023] [Indexed: 07/15/2023] Open
Abstract
Despite the progress made in reducing malaria burden, new ways to address the increasing challenges of insecticide resistance and the invasion and spread of exotic malaria vectors such as Anopheles stephensi in Africa are urgently needed. While African countries are adopting larviciding as a complementary intervention for malaria vector control, the autodissemination technology has the potential to overcome barriers associated with the identification and treatment of prolific habitats that impede conventional larviciding approaches in rural settings. The autodissemination technology as a "lure and release" strategy works by exploiting the resting behavior of gravid mosquitoes to transfer lethal concentration of biological or chemical insecticide such as pyriproxyfen (PPF), an insect growth regulator (IGRs) to their oviposition sites and result in adult emergence inhibition. Despite the evidence of the autodissemination approach to control other mosquito-borne diseases, there is growing and promising evidence for its use in controlling malaria vectors in Africa, which highlights the momentous research that needs to be sustained. This article reviews the evidence for efficacy of the autodissemination approach using PPF and discusses its potential as efficient and affordable complementary malaria vector control intervention in Africa. In the previous studies that were done in controlled semi-field environments, autodissemination with PPF demonstrated its potential in reducing densities of captive population of malaria vectors such as Anopheles gambiae and Anopheles arabiensis. Of importance, empirical evidence and biology-informed mathematical models to demonstrate the utility of the autodissemination approach to control wild populations of malaria vectors under field environment either alone or in combination with other tools are underway. Among others, the key determining factors for future introduction of this approach at scale is having scalable autodissemination devices, optimized PPF formulations, assess its integration/complementarity to existing conventional larviciding, and community perception and acceptance of the autodissemination approach.
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Affiliation(s)
- Augustino Thabiti Mmbaga
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Morogoro, P.O. Box 53, Tanzania
| | - Dickson Wilson Lwetoijera
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Morogoro, P.O. Box 53, Tanzania
- School of Life Sciences and Bio Engineering, Nelson Mandela African Institution of Science and Technology, Tengeru, Arusha, P.O. Box 447, Tanzania
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Liheluka EA, Massawe IS, Chiduo MG, Mandara CI, Chacky F, Ndekuka L, Temba FF, Mmbando BP, Seth MD, Challe DP, Makunde WH, Mhina AD, Baraka V, Segeja MD, Derua YA, Batengana BM, Hayuma PM, Madebe RA, Malimi MC, Mandike R, Mkude S, Molteni F, Njau R, Mohamed A, Rumisha SF, Ishengoma DS. Community knowledge, attitude, practices and beliefs associated with persistence of malaria transmission in North-western and Southern regions of Tanzania. Malar J 2023; 22:304. [PMID: 37817185 PMCID: PMC10563328 DOI: 10.1186/s12936-023-04738-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 10/03/2023] [Indexed: 10/12/2023] Open
Abstract
BACKGROUND Despite significant decline in the past two decades, malaria is still a major public health concern in Tanzania; with over 93% of the population still at risk. Community knowledge, attitudes and practices (KAP), and beliefs are key in enhancing uptake and utilization of malaria control interventions, but there is a lack of information on their contribution to effective control of the disease. This study was undertaken to determine KAP and beliefs of community members and service providers on malaria, and how they might be associated with increased risk and persistence of the disease burden in North-western and Southern regions of Tanzania. METHODS This was an exploratory study that used qualitative methods including 16 in-depth interviews (IDI) and 32 focus group discussions (FGDs) to collect data from health service providers and community members, respectively. The study was conducted from September to October 2017 and covered 16 villages within eight districts from four regions of mainland Tanzania (Geita, Kigoma, Mtwara and Ruvuma) with persistently high malaria transmission for more than two decades. RESULTS Most of the participants had good knowledge of malaria and how it is transmitted but some FGD participants did not know the actual cause of malaria, and thought that it is caused by bathing and drinking un-boiled water, or consuming contaminated food that has malaria parasites without warming it. Reported barriers to malaria prevention and control (by FGD and IDI participants) included shortage of qualified health workers, inefficient health financing, low care-seeking behaviour, consulting traditional healers, use of local herbs to treat malaria, poverty, increased breeding sites by socio-economic activities and misconceptions related to the use of bed nets and indoor residual spraying (IRS). Among the misconceptions, some participants believed that bed nets provided for free by the government came with bedbugs while others reported that free bed nets caused impotence among men. CONCLUSION Despite good knowledge of malaria, several risk factors, such as socio-economic and behavioural issues, and misconceptions related to the use of bed nets and IRS were reported. Other key factors included unavailability or limited access to health services, poor health financing and economic activities that potentially contributed to persistence of malaria burden in these regions. Relevant policies and targeted malaria interventions, focusing on understanding socio-cultural factors, should be implemented to reduce and finally eliminate the disease in the study regions and others with persistent transmission.
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Affiliation(s)
| | | | - Mercy G Chiduo
- National Institute for Medical Research, Tanga, Tanzania
| | - Celine I Mandara
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Frank Chacky
- National Malaria Control Programme, Dodoma, Tanzania
| | - Leah Ndekuka
- National Malaria Control Programme, Dodoma, Tanzania
| | | | | | - Misago D Seth
- National Institute for Medical Research, Tanga, Tanzania
| | | | | | | | - Vito Baraka
- National Institute for Medical Research, Tanga, Tanzania
| | | | - Yahya A Derua
- National Institute for Medical Research, Amani Medical Research Centre, Tanga, Tanzania
| | - Bernard M Batengana
- National Institute for Medical Research, Amani Medical Research Centre, Tanga, Tanzania
| | - Paul M Hayuma
- National Institute for Medical Research, Tanga, Tanzania
| | - Rashid A Madebe
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | | | | | | | | | - Ritha Njau
- World Health Organization Country Office, Dar es Salaam, Tanzania
| | - Ally Mohamed
- National Malaria Control Programme, Dodoma, Tanzania
| | - Susan F Rumisha
- National Institute for Medical Research, Dar es Salaam, Tanzania
- Malaria Atlas Project, Geospatial Health and Development, Telethon Kids Institute, Perth, WA, Australia
| | - Deus S Ishengoma
- National Institute for Medical Research, Dar es Salaam, Tanzania
- Faculty of Pharmaceutical Sciences, Monash University, Melbourne, Australia
- Harvard T.H Chan School of Public Health, Harvard University, Boston, MA, USA
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Kihwele F, Gavana T, Makungu C, Msuya HM, Mlacha YP, Govella NJ, Chaki PP, Sunguya BF. Exploring activities and behaviours potentially increases school-age children's vulnerability to malaria infections in south-eastern Tanzania. Malar J 2023; 22:293. [PMID: 37789435 PMCID: PMC10548596 DOI: 10.1186/s12936-023-04703-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 09/02/2023] [Indexed: 10/05/2023] Open
Abstract
BACKGROUND Strengthening malaria control activities in Tanzania has dramatically declined human malaria infections. However, there is an increasing epidemiological shift in the burden on school-age children. The underlying causes for such an epidemiological shift remain unknown in this context. This study explored activities and behaviours that could increase the vulnerability of school-age children to transmission risk to provide insight into protection gap with existing interventions and opportunities for supplementary interventions. METHODS This cross-sectional study conducted twenty-four focus group discussions (FGDs) in three districts of Rufiji, Kibiti and Kilwa in south-eastern Tanzania. Sixteen FGDs worked with school-age children (13 to 18 years) separating girls and boys and eight FGDs with their parents in mixed-gender groups. A total of 205 community members participated in FGDs across the study area. Of them, 72 participants were parents, while 133 were school-age children (65 boys and 68 girls). RESULTS Routine domestic activities such as fetching water, washing kitchen utensils, cooking, and recreational activities such as playing and watching television and studying were the reported activities that kept school-age children outdoors early evening to night hours (between 18:00 and 23:00). Likewise, the social and cultural events including initiation ceremonies and livelihood activities also kept this age group outdoors from late evening to early night and sometimes past midnight hours. Parents migrating to farms from December to June, leaving behind school-age children unsupervised affecting their net use behaviour plus spending more time outdoors at night, and the behaviour of children sprawling legs and hands while sleeping inside treated bed nets were identified as potential risks to infectious mosquito bites. CONCLUSION The risky activities, behaviours, and social events mostly occurring outdoors might increase school-age children's vulnerability to malaria infections. The findings provide preliminary insight on potential risk factors for persisting transmission. Further studies to quantify the risk behaviour and activities are recommended to establish the magnitude and anticipated impact on supplementary control strategies to control infection in school-age children.
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Affiliation(s)
- Fadhila Kihwele
- Environmental Health and Ecological Sciences Department, #5 Ifakara Street, Plot 463 Mikocheni, P.O. Box 78373, Dar Es Salaam, United Republic of Tanzania.
- Muhimbili University of Health and Allied Sciences, P.O. Box 65001, Dar es Salaam, United Republic of Tanzania.
| | - Tegemeo Gavana
- Environmental Health and Ecological Sciences Department, #5 Ifakara Street, Plot 463 Mikocheni, P.O. Box 78373, Dar Es Salaam, United Republic of Tanzania
- Muhimbili University of Health and Allied Sciences, P.O. Box 65001, Dar es Salaam, United Republic of Tanzania
| | - Christina Makungu
- Environmental Health and Ecological Sciences Department, #5 Ifakara Street, Plot 463 Mikocheni, P.O. Box 78373, Dar Es Salaam, United Republic of Tanzania
| | - Hajirani M Msuya
- Environmental Health and Ecological Sciences Department, #5 Ifakara Street, Plot 463 Mikocheni, P.O. Box 78373, Dar Es Salaam, United Republic of Tanzania
| | - Yeromin P Mlacha
- Environmental Health and Ecological Sciences Department, #5 Ifakara Street, Plot 463 Mikocheni, P.O. Box 78373, Dar Es Salaam, United Republic of Tanzania
| | - Nicodem James Govella
- Environmental Health and Ecological Sciences Department, #5 Ifakara Street, Plot 463 Mikocheni, P.O. Box 78373, Dar Es Salaam, United Republic of Tanzania
- School of Life Sciences and Bioengineering (LISBE), Nelson Mandela African Institution of Science and Technology, P.O. BOX 447, Tengeru, Arusha, United Republic of Tanzania
| | - Prosper Pius Chaki
- Environmental Health and Ecological Sciences Department, #5 Ifakara Street, Plot 463 Mikocheni, P.O. Box 78373, Dar Es Salaam, United Republic of Tanzania
- The Pan African Mosquito Control Association (PAMCA), KEMRI Headquarters, Mbagathi Road Nairobi, Nairobi, 54840-00200, Kenya
| | - Bruno Fokas Sunguya
- Muhimbili University of Health and Allied Sciences, P.O. Box 65001, Dar es Salaam, United Republic of Tanzania
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Coleman S, Yihdego Y, Gyamfi F, Kolyada L, Tongren JE, Zigirumugabe S, Dery DB, Badu K, Obiri-Danso K, Boakye D, Szumlas D, Armistead JS, Dadzie SK. Estimating malaria transmission risk through surveillance of human-vector interactions in northern Ghana. Parasit Vectors 2023; 16:205. [PMID: 37337221 DOI: 10.1186/s13071-023-05793-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 04/28/2023] [Indexed: 06/21/2023] Open
Abstract
BACKGROUND Vector bionomics are important aspects of vector-borne disease control programs. Mosquito-biting risks are affected by environmental, mosquito behavior and human factors, which are important for assessing exposure risk and intervention impacts. This study estimated malaria transmission risk based on vector-human interactions in northern Ghana, where indoor residual spraying (IRS) and insecticide-treated nets (ITNs) have been deployed. METHODS Indoor and outdoor human biting rates (HBRs) were measured using monthly human landing catches (HLCs) from June 2017 to April 2019. Mosquitoes collected were identified to species level, and Anopheles gambiae sensu lato (An. gambiae s.l.) samples were examined for parity and infectivity. The HBRs were adjusted using mosquito parity and human behavioral observations. RESULTS Anopheles gambiae was the main vector species in the IRS (81%) and control (83%) communities. Indoor and outdoor HBRs were similar in both the IRS intervention (10.6 vs. 11.3 bites per person per night [b/p/n]; z = -0.33, P = 0.745) and control communities (18.8 vs. 16.4 b/p/n; z = 1.57, P = 0.115). The mean proportion of parous An. gambiae s.l. was lower in IRS communities (44.6%) than in control communities (71.7%). After adjusting for human behavior observations and parity, the combined effect of IRS and ITN utilization (IRS: 37.8%; control: 57.3%) on reducing malaria transmission risk was 58% in IRS + ITN communities and 27% in control communities with ITNs alone (z = -4.07, P < 0.001). However, this also revealed that about 41% and 31% of outdoor adjusted bites in IRS and control communities respectively, occurred before bed time (10:00 pm). The mean directly measured annual entomologic inoculation rates (EIRs) during the study were 6.1 infective bites per person per year (ib/p/yr) for IRS communities and 16.3 ib/p/yr for control communities. After considering vector survival and observed human behavior, the estimated EIR for IRS communities was 1.8 ib/p/yr, which represents about a 70% overestimation of risk compared to the directly measured EIR; for control communities, it was 13.6 ib/p/yr (16% overestimation). CONCLUSION Indoor residual spraying significantly impacted entomological indicators of malaria transmission. The results of this study indicate that vector bionomics alone do not provide an accurate assessment of malaria transmission exposure risk. By accounting for human behavior parameters, we found that high coverage of ITNs alone had less impact on malaria transmission indices than combining ITNs with IRS, likely due to observed low net use. Reinforcing effective communication for behavioral change in net use and IRS could further reduce malaria transmission.
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Affiliation(s)
- Sylvester Coleman
- U.S. President's Malaria Initiative VectorLink Project, Accra, Ghana.
- Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Yemane Yihdego
- U.S. President's Malaria Initiative VectorLink Project, Accra, Ghana
| | - Frank Gyamfi
- U.S. President's Malaria Initiative VectorLink Project, Accra, Ghana
| | - Lena Kolyada
- U.S. President's Malaria Initiative VectorLink Project, Accra, Ghana
| | - Jon Eric Tongren
- U.S. President's Malaria Initiative, Malaria Branch, U.S. Centers for Disease Control and Prevention, Accra, Ghana
| | - Sixte Zigirumugabe
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Accra, Ghana
| | - Dominic B Dery
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Accra, Ghana
| | - Kingsley Badu
- Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | | | - Daniel Boakye
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Daniel Szumlas
- Armed Forces Pest Management Board, 172 Forney Road, Forest Glen Annex, Silver Spring, MD, 20910, USA
| | - Jennifer S Armistead
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA
| | - Samuel K Dadzie
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
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Vanhuysse S, Diédhiou SM, Grippa T, Georganos S, Konaté L, Niang EHA, Wolff E. Fine-scale mapping of urban malaria exposure under data scarcity: an approach centred on vector ecology. Malar J 2023; 22:113. [PMID: 37009873 PMCID: PMC10069057 DOI: 10.1186/s12936-023-04527-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 03/08/2023] [Indexed: 04/04/2023] Open
Abstract
BACKGROUND Although malaria transmission has experienced an overall decline in sub-Saharan Africa, urban malaria is now considered an emerging health issue due to rapid and uncontrolled urbanization and the adaptation of vectors to urban environments. Fine-scale hazard and exposure maps are required to support evidence-based policies and targeted interventions, but data-driven predictive spatial modelling is hindered by gaps in epidemiological and entomological data. A knowledge-based geospatial framework is proposed for mapping the heterogeneity of urban malaria hazard and exposure under data scarcity. It builds on proven geospatial methods, implements open-source algorithms, and relies heavily on vector ecology knowledge and the involvement of local experts. METHODS A workflow for producing fine-scale maps was systematized, and most processing steps were automated. The method was evaluated through its application to the metropolitan area of Dakar, Senegal, where urban transmission has long been confirmed. Urban malaria exposure was defined as the contact risk between adult Anopheles vectors (the hazard) and urban population and accounted for socioeconomic vulnerability by including the dimension of urban deprivation that is reflected in the morphology of the built-up fabric. Larval habitat suitability was mapped through a deductive geospatial approach involving the participation of experts with a strong background in vector ecology and validated with existing geolocated entomological data. Adult vector habitat suitability was derived through a similar process, based on dispersal from suitable breeding site locations. The resulting hazard map was combined with a population density map to generate a gridded urban malaria exposure map at a spatial resolution of 100 m. RESULTS The identification of key criteria influencing vector habitat suitability, their translation into geospatial layers, and the assessment of their relative importance are major outcomes of the study that can serve as a basis for replication in other sub-Saharan African cities. Quantitative validation of the larval habitat suitability map demonstrates the reliable performance of the deductive approach, and the added value of including local vector ecology experts in the process. The patterns displayed in the hazard and exposure maps reflect the high degree of heterogeneity that exists throughout the city of Dakar and its suburbs, due not only to the influence of environmental factors, but also to urban deprivation. CONCLUSIONS This study is an effort to bring geospatial research output closer to effective support tools for local stakeholders and decision makers. Its major contributions are the identification of a broad set of criteria related to vector ecology and the systematization of the workflow for producing fine-scale maps. In a context of epidemiological and entomological data scarcity, vector ecology knowledge is key for mapping urban malaria exposure. An application of the framework to Dakar showed its potential in this regard. Fine-grained heterogeneity was revealed by the output maps, and besides the influence of environmental factors, the strong links between urban malaria and deprivation were also highlighted.
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Affiliation(s)
- Sabine Vanhuysse
- Department of Geosciences, Environment and Society, Université Libre de Bruxelles (ULB), 1050, Brussels, Belgium.
| | - Seynabou Mocote Diédhiou
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Université Cheikh-Anta-Diop de Dakar, Dakar, Sénégal
| | - Taïs Grippa
- Department of Geosciences, Environment and Society, Université Libre de Bruxelles (ULB), 1050, Brussels, Belgium
| | - Stefanos Georganos
- Geomatics, Department of Environmental and Life Sciences, Faculty of Health, Science and Technology, Karlstad University, Karlstad, Sweden
| | - Lassana Konaté
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Université Cheikh-Anta-Diop de Dakar, Dakar, Sénégal
| | - El Hadji Amadou Niang
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Université Cheikh-Anta-Diop de Dakar, Dakar, Sénégal
| | - Eléonore Wolff
- Department of Geosciences, Environment and Society, Université Libre de Bruxelles (ULB), 1050, Brussels, Belgium
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Mmbaga AT, Lwetoijera DW. Current and future opportunities of autodissemination of pyriproxyfen approach for malaria vector control in urban and rural Africa. Wellcome Open Res 2023. [DOI: 10.12688/wellcomeopenres.19131.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Abstract
Despite the progress made in reducing malaria burden, new ways to address the increasing challenges of insecticide resistance and the invasion and spread of exotic malaria vectors such as Anopheles stephensi in Africa are urgently needed. While African countries are adopting larviciding as a complementary intervention for malaria vector control, the autodissemination technology has the potential to overcome barriers associated with the identification and treatment of prolific habitats that impede conventional larviciding approaches in rural settings. The autodissemination technology as a “lure and release” strategy works by exploiting the resting behavior of gravid mosquitoes to transfer lethal concentration of biological or chemical insecticide such as pyriproxyfen (PPF), an insect growth regulator (IGRs) to their oviposition sites and result in adult emergence. Despite the evidence of the autodissemination approach to control other mosquito-borne diseases, there is growing and promising evidence for its use in controlling malaria vectors in Africa, which highlights the momentous research that needs to be sustained. This article reviews the evidence for efficacy of the autodissemination approach using PPF and discusses its potential as efficient and affordable complementary malaria vector control intervention in Africa. In the previous studies that were done in controlled semi-field environments, autodissemination with PPF demonstrated its potential in reducing densities of captive population of malaria vectors such as Anopheles gambiae and Anopheles arabiensis. Of importance, empirical evidence and biology-informed mathematical models to demonstrate the utility of the autodissemination approach to control wild populations of malaria vectors under field environment either alone or in combination with other tools are underway. Among others, the key determining factors for future introduction of this approach at scale is having scalable autodissemination devices, optimized PPF formulations, assess its integration/complementarity to existing conventional larviciding, and community perception and acceptance of the autodissemination approach.
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Musoke D, Atusingwize E, Namata C, Ndejjo R, Wanyenze RK, Kamya MR. Integrated malaria prevention in low- and middle-income countries: a systematic review. Malar J 2023; 22:79. [PMID: 36879237 PMCID: PMC9987134 DOI: 10.1186/s12936-023-04500-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 02/16/2023] [Indexed: 03/08/2023] Open
Abstract
BACKGROUND As many countries aim to eliminate malaria, use of comprehensive approaches targeting the mosquito vector and environment are needed. Integrated malaria prevention advocates the use of several malaria prevention measures holistically at households and in the community. The aim of this systematic review was to collate and summarize the impact of integrated malaria prevention in low- and middle-income countries on malaria burden. METHODS Literature on integrated malaria prevention, defined as the use of two or more malaria prevention methods holistically, was searched from 1st January 2001 to 31st July 2021. The primary outcome variables were malaria incidence and prevalence, while the secondary outcome measures were human biting and entomological inoculation rates, and mosquito mortality. RESULTS A total of 10,931 studies were identified by the search strategy. After screening, 57 articles were included in the review. Studies included cluster randomized controlled trials, longitudinal studies, programme evaluations, experimental hut/houses, and field trials. Various interventions were used, mainly combinations of two or three malaria prevention methods including insecticide-treated nets (ITNs), indoor residual spraying (IRS), topical repellents, insecticide sprays, microbial larvicides, and house improvements including screening, insecticide-treated wall hangings, and screening of eaves. The most common methods used in integrated malaria prevention were ITNs and IRS, followed by ITNs and topical repellents. There was reduced incidence and prevalence of malaria when multiple malaria prevention methods were used compared to single methods. Mosquito human biting and entomological inoculation rates were significantly reduced, and mosquito mortality increased in use of multiple methods compared to single interventions. However, a few studies showed mixed results or no benefits of using multiple methods to prevent malaria. CONCLUSION Use of multiple malaria prevention methods was effective in reducing malaria infection and mosquito density in comparison with single methods. Results from this systematic review can be used to inform future research, practice, policy and programming for malaria control in endemic countries.
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Affiliation(s)
- David Musoke
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda.
| | - Edwinah Atusingwize
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Carol Namata
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Rawlance Ndejjo
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Rhoda K Wanyenze
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Moses R Kamya
- Department of Medicine, School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
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13
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Ngonghala CN. Assessing the impact of insecticide-treated nets in the face of insecticide resistance on malaria control. J Theor Biol 2022; 555:111281. [PMID: 36154815 DOI: 10.1016/j.jtbi.2022.111281] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 09/01/2022] [Accepted: 09/17/2022] [Indexed: 01/14/2023]
Abstract
The mosquito-borne disease, malaria, continues to impose a devastating health and economic burden worldwide. In malaria-endemic areas, insecticide-treated nets (ITNs) have been useful in curtailing the burden of the disease. However, mosquito resistance to insecticides, decay in ITN efficacy, net attrition, etc., undermine the effectiveness of ITNs in combatting malaria. In this study, mathematical models that account for asymptomatic infectious humans (through a partially immune class or a separate asymptomatic infectious class), insecticide resistance, and decay in ITN efficacy are proposed and analyzed. Analytical and numerical results of the models when ITN efficacy is constant show that there are parameter regimes for which a backward bifurcation occurs. Local and global sensitivity analyses are performed to identify parameters (some of which are potential targets for disease control) with the most significant influence on the control reproduction (Rc) and disease prevalence. These influential parameters include the maximum biting rate of resistant mosquitoes, ITN coverage, initial ITN efficacy against sensitive mosquitoes, the probability that an infectious mosquito (human) infects a susceptible human (mosquito), and the rate at which adult mosquitoes develop (lose) resistance to insecticides. Simulations of the models show that accounting for asymptomatic infectious humans through a separate class, or not accounting for the decay in ITN efficacy leads to an underestimation of disease burden. In particular, if the initial efficacy of ITNs against sensitive and resistance mosquitoes is 96%, the minimum ITN coverage required to reduce Rc below one (and hence, contain malaria) is approximately 11% (27%) lower when ITN efficacy is averaged (constant) for a model with a separate asymptomatic class. For the model with a partially immune class and decaying ITN efficacy, reducing Rc below one is impossible even if the entire populace uses ITNs. The study shows that replacing ITNs before their prescribed lifespans, or designing ITNs with longer lifespans is important for malaria control. Furthermore, the study shows that piperonyl butoxide (PBO) ITNs (which inhibit or reverse insecticide resistance) outperform regular ITNs in malaria control. Hence, prospects for effectively controlling malaria are enhanced by widespread use of high quality ITNs (e.g. PBO ITNs), especially if the useful lifespans of the ITNs are long enough and the ITNs are replaced before the end of their useful lifespans.
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Affiliation(s)
- Calistus N Ngonghala
- Department of Mathematics, University of Florida, 1400 Stadium Rd, Gainesville, FL 32611, United States of America; Emerging Pathogens Institute, University of Florida, 2055 Mowry Rd, Gainesville, FL 32610, United States of America; Center for African Studies, University of Florida, 427 Grinter Hall 1523 Union Rd, Gainesville, FL 32611, United States of America.
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14
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Katusi GC, Hermy MRG, Makayula SM, Ignell R, Govella NJ, Hill SR, Mnyone LL. Seasonal variation in abundance and blood meal sources of primary and secondary malaria vectors within Kilombero Valley, Southern Tanzania. Parasit Vectors 2022; 15:479. [PMID: 36539892 PMCID: PMC9768911 DOI: 10.1186/s13071-022-05586-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 08/20/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Existing control tools have significantly reduced malaria over the past two decades. However, progress has been stalled due to increased resistance in primary vectors and the increasing role of secondary vectors. This study aimed to investigate the impact of seasonal change on primary and secondary vector abundance and host preference. Understanding the impact of seasonal dynamics of primary and secondary vectors on disease transmission will inform effective strategies for vector management and control. METHODS Vector abundance was measured through longitudinal collection of mosquitoes, conducted monthly during the wet and dry seasons, in Sagamaganga, a village in the Kilombero Valley, Tanzania. Mosquitoes were collected indoors using CDC light traps and backpack aspirators, and outdoors using resting buckets baited with cattle urine. In addition, a direct measure of host preference was taken monthly using human- and cattle-baited mosquito electrocuting traps. A host census was conducted to provide an indirect measure of host preference together with monthly blood meal source analysis. All collected mosquitoes were assayed for Plasmodium sporozoites. RESULTS A total of 2828 anophelines were collected, of which 78.5% and 21.4%, were primary and secondary vectors, respectively. The abundance of the primary vectors, Anopheles arabiensis and Anopheles funestus, and of the secondary vectors varied seasonally. Indirect measures of host preference indicated that all vectors varied blood meal choice seasonally, with the direct measure confirming this for An. arabiensis. All anopheline mosquitoes tested negative for sporozoites. CONCLUSIONS At the study location, the abundance of both primary and secondary vectors changed seasonally. Indirect and direct measures of host preference demonstrated that An. arabiensis varied from being zoophilic to being more opportunistic during the wet and dry seasons. A similar trend was observed for the other vectors.
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Affiliation(s)
- Godfrey C. Katusi
- grid.414543.30000 0000 9144 642XDepartment of Environmental Health and Ecological Sciences, Ifakara Health Institute, Off Mlabani Passage, Ifakara, P.O. Box 53, Morogoro, Tanzania ,grid.11887.370000 0000 9428 8105Department of Microbiology, Parasitology and Biotechnology, College of Veterinary Medicine and Biomedical Sciences, Sokoine University of Agriculture, P.O. Box 3019, Morogoro, Tanzania
| | - Marie R. G. Hermy
- grid.6341.00000 0000 8578 2742Disease Vector Group, Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P.O. Box 190, 234 22 Lomma, Sweden
| | - Samwely M. Makayula
- grid.414543.30000 0000 9144 642XDepartment of Environmental Health and Ecological Sciences, Ifakara Health Institute, Off Mlabani Passage, Ifakara, P.O. Box 53, Morogoro, Tanzania
| | - Rickard Ignell
- grid.6341.00000 0000 8578 2742Disease Vector Group, Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P.O. Box 190, 234 22 Lomma, Sweden
| | - Nicodem J. Govella
- grid.414543.30000 0000 9144 642XDepartment of Environmental Health and Ecological Sciences, Ifakara Health Institute, Off Mlabani Passage, Ifakara, P.O. Box 53, Morogoro, Tanzania ,grid.451346.10000 0004 0468 1595School of Life Sciences and Bioengineering, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
| | - Sharon R. Hill
- grid.6341.00000 0000 8578 2742Disease Vector Group, Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P.O. Box 190, 234 22 Lomma, Sweden
| | - Ladslaus L. Mnyone
- grid.11887.370000 0000 9428 8105Pest Management Centre, Sokoine University of Agriculture, P.O. Box 3110, Morogoro, Tanzania
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15
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Abstract
Given the stagnating progress in the fight against malaria, there is an urgent need for area-wide integrated vector management strategies to complement existing intra-domiciliary tools, i.e., insecticide-treated bednets and indoor residual spraying. In this study, we describe a pilot trial using drones for aerial application of Aquatain Mosquito Formulation (AMF), a monomolecular surface film with larvicidal activity, against the African malaria mosquito Anopheles arabiensis in an irrigated rice agro-ecosystem in Unguja island, Zanzibar, Tanzania. Nine rice paddies were randomly assigned to three treatments: (a) control (drone spraying with water only), (b) drone spraying with 1 mL/m2, or (c) drone spraying with 5 mL/m2 of AMF. Compared to control paddies, AMF treatments resulted in highly significant (p < 0.001) reductions in the number of larvae and pupae and >90% fewer emerging adults. The residual effect of AMF treatment lasted for a minimum of 5 weeks post-treatment, with reductions in larval densities reaching 94.7% in week 5 and 99.4% in week 4 for the 1 and 5 mL/m2 AMF treatments, respectively. These results merit a review of the WHO policy regarding larval source management (LSM), which primarily recommends its use in urban environments with ‘few, fixed, and findable’ breeding sites. Unmanned aerial vehicles (UAVs) can rapidly treat many permanent, temporary, or transient mosquito breeding sites over large areas at low cost, thereby significantly enhancing the role of LSM in contemporary malaria control and elimination efforts.
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David Forfuet F, Mayi MPA, Fru-Cho J, Kowo C, Nota Anong D, Esack Fonda A, Djomo C, Tchuinkam T, Brisco KK, Sehgal R, John Cornel A. Efficacy of Trapping Methods in the Collection of Eretmapodites (Diptera: Culicidae) Mosquitoes in an Afrotropical Rainforest Region, South western Cameroon. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:1394-1403. [PMID: 35640028 DOI: 10.1093/jme/tjac060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Indexed: 06/15/2023]
Abstract
Very little data exist on the biology of an afrotropical rainforest mosquito Eretmapodites (Er.) in a world undergoing dramatic changes due to deforestation. The aim was to assess the efficacy of different trapping methods in the collection of Er. mosquito in forested area. This was a longitudinal study involving collection of mosquitoes for over two years. Multiple collection methods (grouped into two categories), were used; i) net baited and un-baited traps to collect adults, ii) techniques that target immature stages subsequently reared to adults. All males were identified by genitalia dissection. Five thousand seven hundred and four mosquitoes representing 11 genera among which 2,334 Er. were identified. Mosquito abundance was highest in the net traps (n = 1276 (56.4%)) and sweep nets (n = 393(17.4%)) respectively. The abundance was highest in green colored net traps (435(34.09%)) with significant value of χ2= 40.000, P < 0.001 and in pigeons baited traps (473 (37.06%)) with significant value of χ2= 42.000, P = 0.003. The diversity ranges from H' = 2.65; DS = 0.84; SR = 24; ACE = 24.77 in sweep net to H' = 0; DS = 0; SR = 1; ACE = 1 in rock pool among males mosquitoes. While for females, H = 1.14; DS = 0.71; SR = 5; ACE = 5.16, in sweep net to H = 0; DS = 0; SR = 1; ACE = 1 in rock pool, tarpaulin, resting cage. Net traps, bamboo pot, and sweep netting are efficient in collecting high abundance of forest mosquitoes in the Talanagaye rainforest.
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Affiliation(s)
| | - Marie Paul Audrey Mayi
- Vector Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Sciences of the University of Dschang, Cameroon
| | - Jerome Fru-Cho
- Department of Microbiology and Parasitology, University of Buea, Cameroon
| | - Cyril Kowo
- Department of Microbiology and Parasitology, University of Buea, Cameroon
| | - Damian Nota Anong
- Department of Microbiology and Parasitology, University of Buea, Cameroon
| | | | - Charlene Djomo
- Higher Institute of Environmental Science, Department of Environmental Health, PO Box 35460, Yaounde, Cameroon
| | - Timoleon Tchuinkam
- Vector Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Sciences of the University of Dschang, Dschang, Cameroon
| | - Katherine K Brisco
- Mosquito Control Research Laboratory, Department of Entomology and Nematology and Vector Genetics Laboratory, Department of Pathology, Microbiology and Immunology, University of California at Davis, Parlier, CA, USA
| | - Ravinder Sehgal
- Department of Biology, San Francisco State University, San Francisco, CA, USA
| | - Anthony John Cornel
- Mosquito Control Research Laboratory, Department of Entomology and Nematology and Vector Genetics Laboratory, Department of Pathology, Microbiology and Immunology, University of California at Davis, Parlier, CA, USA
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García GA, Fuseini G, Mba Nlang JA, Nsue Maye VO, Bela NR, Wofford RN, Weppelmann TA, Matulis G, Efiri PB, Smith JM, Rivas MR, Phiri WP, von Fricken ME. Evaluation of a Multi-Season, Community-Based Larval Source Management Program on Bioko Island, Equatorial Guinea. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2022.846955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BackgroundIn 2015 and 2016, the Bioko Island Malaria Control Project (BIMCP) introduced a pilot larvicide program, which recruited local volunteers to assess the sustainability and effectiveness of community-led larval source management. This study evaluates the effectiveness of the community-led LSM program to determine if this type of intervention could be used as a sustainable malaria control method on Bioko Island.MethodsThe pilot program was split into two phases, both taking place between February and December, with phase I in 2015 and phase II in 2016. During phase I, the BIMCP team assisted in identifying and treating Anopheles species mosquito breeding habitats. During phase II, community volunteers, with supervision from designated community leaders, identified and treated breeding habitats. Larval source management took place at thirteen locations around the Island during both phases. Human landing catches were conducted at seven sentinel sites once every month for the duration of the study period to determine average nightly biting rates.ResultsDuring phase I, 1,033 breeding sites were identified with a 100% treatment coverage rate. Only 970 breeding sites were identified in phase II with a 75% treatment coverage rate, a significant decrease from phase I (p<0.001). Between phase I and phase II, larvicide usage also decreased by 45% (95% CI: 32, 59%, p=0.003). However, excluding the sentinel site Balboa, vector density showed a nonsignificant (p=0.272) relationship between phase I and phase II.ConclusionOverall, community-based larval source management can be effective with strong operational management and oversight. However, repeated training and evaluation will be necessary to monitor the effectiveness and sustainability of such interventions.
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Msellemu D, Ross A, Temu L, Moshi I, Hofer L, Mwanziva C, Kohi YM, Moore SJ. Effect of interventions to reduce malaria incidence among military personnel on active duty: study protocol for a cluster randomised controlled trial of the impact of etofenprox-treated uniforms, permethrin-treated uniforms and DEET insect repellent. Trials 2021; 22:825. [PMID: 34802455 PMCID: PMC8607639 DOI: 10.1186/s13063-021-05801-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 11/05/2021] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND While there is strong evidence that bite protection methods such as permethrin-treated clothing and topical insect repellents are protective against insect bites, there are few studies assessing the impact on malaria infection. This study will estimate the protective efficacy of treated uniforms and DEET insect repellent on the incidence of malaria infection among military personnel in an operational setting. Permethrin-treated uniforms used with DEET lotion will be compared to etofenprox-treated uniforms with DEET lotion. The effect of DEET lotion will be estimated by comparing permethrin-treated uniforms with DEET or placebo lotion. METHOD A cluster randomised double-blind placebo-controlled trial is planned to evaluate the effectiveness of the interventions on preventing malaria infections in soldiers on active duty at Mgambo National Service Camp in Tanga, Tanzania. The arms are (1) permethrin-treated uniform with 30% DEET liposome formula; (2) permethrin-treated uniform with placebo lotion; (3) candidate insect repellent system, i.e. etofenprox-treated uniform with 30% DEET liposome formula; and (4) placebo, i.e. untreated uniforms with placebo lotion. The primary outcome is the incidence of Plasmodium falciparum malaria infection detected by polymerase chain reaction (PCR) by active case detection using surveys every 2 weeks for 12 months. Rapid diagnostic tests will be used for the diagnosis of participants with symptoms. The unit of randomisation will be combania: companies formed by recruits aged 18 to 25 years; combania do activities together and sleep in the same dormitory. Unequal randomisation will be used to optimise statistical power for the primary comparison between permethrin-treated uniforms with DEET and etofenprox-treated uniforms with DEET. DISCUSSION This trial will provide the estimate of the effects of permethrin with DEET compared to those of the new fabric treatment etofenprox with DEET and any additional effect of using DEET. The results will inform strategies to protect military personnel and civilians who have more outdoor or occupational malaria exposure than the general public. TRIAL REGISTRATION ClinicalTrials.gov NCT02938975 .
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Affiliation(s)
- Daniel Msellemu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland
- University of Basel, Petersplatz 1, 4003 Basel, Switzerland
| | - Amanda Ross
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland
- University of Basel, Petersplatz 1, 4003 Basel, Switzerland
| | - Lucky Temu
- HJF Medical Research International (HJFMRI), Walter Reed Program, Tanzania, P.O. Box 13303, Dar es Salaam, Tanzania
| | - Irene Moshi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Lorenz Hofer
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland
- University of Basel, Petersplatz 1, 4003 Basel, Switzerland
| | - Charles Mwanziva
- Tanzania People’s Defence Force, Magore Upanga, P.O. Box 9203, Dar es Salaam, Tanzania
| | - Yadon M. Kohi
- Tanzania People’s Defence Force, Magore Upanga, P.O. Box 9203, Dar es Salaam, Tanzania
| | - Sarah J. Moore
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland
- University of Basel, Petersplatz 1, 4003 Basel, Switzerland
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Chemical Diversity between Three Graminoid Plants Found in Western Kenya Analyzed by Headspace Solid-Phase Microextraction Gas Chromatography–Mass Spectrometry (HS-SPME-GC-MS). PLANTS 2021; 10:plants10112423. [PMID: 34834786 PMCID: PMC8617917 DOI: 10.3390/plants10112423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/04/2021] [Accepted: 11/04/2021] [Indexed: 11/20/2022]
Abstract
In recent work, it was shown that the graminoid plants Cynodon dactylon (Poaceae), Cyperus exaltatus (Cyperaceae), and Panicum repens (Poaceae) have an ovipositional effect on the malaria vector Anopheles gambiae in olfactometric bioassays. In order to get a view of the diversity of semiochemicals present in the environment of the vector during olfactometric trials, in the present work, the volatile profiles of these graminoid plants were analyzed using headspace solid-phase microextraction (HS-SPME) together with gas chromatography–mass spectrometry (GC-MS). In addition, one-way ANOVA comparison of compounds detected in two or more headspace samples are presented in order to provide a basis for comparison of compounds that could constitute a starting point for novel blends of volatile organic compounds to be tested as oviposition attractants.
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Kaindoa EW, Mmbando AS, Shirima R, Hape EE, Okumu FO. Insecticide-treated eave ribbons for malaria vector control in low-income communities. Malar J 2021; 20:415. [PMID: 34688285 PMCID: PMC8542300 DOI: 10.1186/s12936-021-03945-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 10/06/2021] [Indexed: 12/03/2022] Open
Abstract
Supplementary tools are required to address the limitations of insecticide-treated nets (ITNs) and indoor residual spraying (IRS), which are currently the core vector control methods against malaria in Africa. The eave ribbons technology exploits the natural house-entry behaviours of major malaria vectors to deliver mosquitocidal or repellent actives around eave spaces through which the Anopheles mosquitoes usually enter human dwellings. They confer protection by preventing biting indoors and in the peri-domestic outdoor spaces, and also killing a significant proportion of the mosquitoes. Current versions of eave ribbons are made of low-cost hessian fabric infused with candidate insecticides and can be easily fitted onto multiple house types without any additional modifications. This article reviews the evidence for efficacy of the technology, and discusses its potential as affordable and versatile supplementary approach for targeted and efficient control of mosquito-borne diseases, particularly malaria. Given their simplicity and demonstrated potential in previous studies, future research should investigate ways to optimize scalability and effectiveness of the ribbons. It is also important to assess whether the ribbons may constitute a less-cumbersome, but more affordable substitute for other interventions, such as IRS, by judiciously using lower quantities of selected insecticides targeted around eave spaces to deliver equivalent or greater suppression of malaria transmission.
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Affiliation(s)
- Emmanuel W Kaindoa
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania. .,School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania.
| | - Arnold S Mmbando
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,Department of Biosciences, Durham University, DH13LE, Durham, UK
| | - Ruth Shirima
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Emmanuel E Hape
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G12 8QQ, Glasgow, UK
| | - Fredros O Okumu
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G12 8QQ, Glasgow, UK.,School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania
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21
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Nambunga IH, Msugupakulya BJ, Hape EE, Mshani IH, Kahamba NF, Mkandawile G, Mabula DM, Njalambaha RM, Kaindoa EW, Muyaga LL, Hermy MRG, Tripet F, Ferguson HM, Ngowo HS, Okumu FO. Wild populations of malaria vectors can mate both inside and outside human dwellings. Parasit Vectors 2021; 14:514. [PMID: 34620227 PMCID: PMC8499572 DOI: 10.1186/s13071-021-04989-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 09/01/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Wild populations of Anopheles mosquitoes are generally thought to mate outdoors in swarms, although once colonized, they also mate readily inside laboratory cages. This study investigated whether the malaria vectors Anopheles funestus and Anopheles arabiensis can also naturally mate inside human dwellings. METHOD Mosquitoes were sampled from three volunteer-occupied experimental huts in a rural Tanzanian village at 6:00 p.m. each evening, after which the huts were completely sealed and sampling was repeated at 11:00 p.m and 6 a.m. the next morning to compare the proportions of inseminated females. Similarly timed collections were done inside local unsealed village houses. Lastly, wild-caught larvae and pupae were introduced inside or outside experimental huts constructed inside two semi-field screened chambers. The huts were then sealed and fitted with exit traps, allowing mosquito egress but not entry. Mating was assessed in subsequent days by sampling and dissecting emergent adults caught indoors, outdoors and in exit traps. RESULTS Proportions of inseminated females inside the experimental huts in the village increased from approximately 60% at 6 p.m. to approximately 90% the following morning despite no new mosquitoes entering the huts after 6 p.m. Insemination in the local homes increased from approximately 78% to approximately 93% over the same time points. In the semi-field observations of wild-caught captive mosquitoes, the proportions of inseminated An. funestus were 20.9% (95% confidence interval [CI]: ± 2.8) outdoors, 25.2% (95% CI: ± 3.4) indoors and 16.8% (± 8.3) in exit traps, while the proportions of inseminated An. arabiensis were 42.3% (95% CI: ± 5.5) outdoors, 47.4% (95% CI: ± 4.7) indoors and 37.1% (CI: ± 6.8) in exit traps. CONCLUSION Wild populations of An. funestus and An. arabiensis in these study villages can mate both inside and outside human dwellings. Most of the mating clearly happens before the mosquitoes enter houses, but additional mating happens indoors. The ecological significance of such indoor mating remains to be determined. The observed insemination inside the experimental huts fitted with exit traps and in the unsealed village houses suggests that the indoor mating happens voluntarily even under unrestricted egress. These findings may inspire improved vector control, such as by targeting males indoors, and potentially inform alternative methods for colonizing strongly eurygamic Anopheles species (e.g. An. funestus) inside laboratories or semi-field chambers.
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Affiliation(s)
- Ismail H. Nambunga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Betwel J. Msugupakulya
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania
| | - Emmanuel E. Hape
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Issa H. Mshani
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Najat F. Kahamba
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania
| | - Gustav Mkandawile
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Daniel M. Mabula
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Rukiyah M. Njalambaha
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Emmanuel W. Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Park Town, Republic of South Africa
| | - Letus L. Muyaga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Marie R. G. Hermy
- Disease Vector Group, Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Frederic Tripet
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Newcastle-under-Lyme, UK
| | - Heather M. Ferguson
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Halfan S. Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Fredros O. Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Park Town, Republic of South Africa
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Pooseesod K, Parker DM, Meemon N, Lawpoolsri S, Singhasivanon P, Sattabongkot J, Cui L, Phuanukoonnon S. Ownership and utilization of bed nets and reasons for use or non-use of bed nets among community members at risk of malaria along the Thai-Myanmar border. Malar J 2021; 20:305. [PMID: 34229653 PMCID: PMC8259116 DOI: 10.1186/s12936-021-03837-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/27/2021] [Indexed: 11/22/2022] Open
Abstract
Background With the goal for malaria elimination in Thailand set for 2024, increased coverage and utilization of bed net, especially insecticide-treated net (ITN) or long-lasting insecticidal net (LLIN) is a key strategy. This study aims to provide the necessary information about bed net ownership and utilization among the population at risk of malaria living along the Thai-Myanmar border in Tak province. Methods A cross-sectional study was conducted using a mixed-method approach in 331 households from 5 hamlets in the villages of the Thai-Myanmar border. The research tools included a questionnaire, bed net inspection, and semi-structured interviews. Logistic regression was used to explore the sociodemographic factors associated with bed net utilization. The qualitative analysis employed a thematic analysis approach. Results This survey found that 98.5% of households had at least one bed net per household, and 74.3% had at least one ITN/LLIN. However, only 30.8% of households reached the standard policy set by the Minister of Public Health of one ITN/LLINs per two persons. Most residents used bed net (92.1% used in the previous night and 80.9% used every day). For those using bed nets, however, 61.9% used ITNs or LLINs the night before and 53.1% used them every day. Nonetheless, the usage rates of bed nets (any type) in the previous night among children and pregnant women were high, reaching 95.3% and 90.0%, respectively. Seven explanatory variables showed statistically significant associations with bed net use every day, including: “not staying overnight in the forest or the field”, “sleeping pattern based on gender”, “sufficient numbers of bed nets to cover all sleeping spaces”, “preference for free bed nets”, “age”, “gender”, and “SES score” showed statistically significant association with bed net use every day. The major reasons for the regular use of bed nets in both household and the forest were to prevent mosquito biting. The reasons for not using bednets in the household were discomfort feelings from heat, perception of unnecessity due to low mosquito density, whereas the reason for not using bed nets in the forest was inconvenience. Conclusion Despite that overall coverage and usage of bed nets was high, only one third reached the standard level specified by the policy. Overnight in the forest, the dissatisfaction with the quality of free bed nets, insufficient number of bed nets, sleeping alone, male gender, age more than 10 years, low socioeconomic status, discomfort from heat, perception of no benefits of bed nets due to low mosquito density, and inconvenience were factors influencing bed net use. Maintaining high coverage and utility rate of bed nets should be a priority for the malaria high-risk population. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03837-5.
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Affiliation(s)
- Kasama Pooseesod
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Nakhon Pathom, Thailand.,Faculty of Public Health, Thammasat University, Bangkok, Thailand
| | - Daniel M Parker
- Department of Population Health & Disease Prevention, Program in Public Health Susan and Henry Samueli College of Health Sciences, University of California, Irvine, USA
| | - Natthani Meemon
- Department of Society and Health, Faculty of Social Sciences and Humanities, Mahidol University, Nakhon Pathom, Thailand
| | - Saranath Lawpoolsri
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Nakhon Pathom, Thailand
| | - Pratap Singhasivanon
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Nakhon Pathom, Thailand.,Faculty of Tropical Medicine, SEAMEO TROPMED Regional Centre for Tropical Medicine, Mahidol University, Nakhon Pathom, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Nakhon Pathom, Thailand
| | - Liwang Cui
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Suparat Phuanukoonnon
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Nakhon Pathom, Thailand. .,Department of Social and Environmental Medicine, Faculty of Tropical Medicine, Mahidol University, Nakhon Pathom, Thailand.
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Phiri MD, McCann RS, Kabaghe AN, van den Berg H, Malenga T, Gowelo S, Tizifa T, Takken W, van Vugt M, Phiri KS, Terlouw DJ, Worrall E. Cost of community-led larval source management and house improvement for malaria control: a cost analysis within a cluster-randomized trial in a rural district in Malawi. Malar J 2021; 20:268. [PMID: 34120608 PMCID: PMC8200285 DOI: 10.1186/s12936-021-03800-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 06/03/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND House improvement (HI) to prevent mosquito house entry, and larval source management (LSM) targeting aquatic mosquito stages to prevent development into adult forms, are promising complementary interventions to current malaria vector control strategies. Lack of evidence on costs and cost-effectiveness of community-led implementation of HI and LSM has hindered wide-scale adoption. This study presents an incremental cost analysis of community-led implementation of HI and LSM, in a cluster-randomized, factorial design trial, in addition to standard national malaria control interventions in a rural area (25,000 people), in southern Malawi. METHODS In the trial, LSM comprised draining, filling, and Bacillus thuringiensis israelensis-based larviciding, while house improvement (henceforth HI) involved closing of eaves and gaps on walls, screening windows/ventilation spaces with wire mesh, and doorway modifications. Communities implemented all interventions. Costs were estimated retrospectively using the 'ingredients approach', combining 'bottom-up' and 'top-down approaches', from the societal perspective. To estimate the cost of independently implementing each intervention arm, resources shared between trial arms (e.g. overheads) were allocated to each consuming arm using proxies developed based on share of resource input quantities consumed. Incremental implementation costs (in 2017 US$) are presented for HI-only, LSM-only and HI + LSM arms. In sensitivity analyses, the effect of varying costs of important inputs on estimated costs was explored. RESULTS The total economic programme costs of community-led HI and LSM implementation was $626,152. Incremental economic implementation costs of HI, LSM and HI + LSM were estimated as $27.04, $25.06 and $33.44, per person per year, respectively. Project staff, transport and labour costs, but not larvicide or screening material, were the major cost drivers across all interventions. Costs were sensitive to changes in staff costs and population covered. CONCLUSIONS In the trial, the incremental economic costs of community-led HI and LSM implementation were high compared to previous house improvement and LSM studies. Several factors, including intervention design, year-round LSM implementation and low human population density could explain the high costs. The factorial trial design necessitated use of proxies to allocate costs shared between trial arms, which limits generalizability where different designs are used. Nevertheless, costs may inform planners of similar intervention packages where cost-effectiveness is known. Trial registration Not applicable. The original trial was registered with The Pan African Clinical Trials Registry on 3 March 2016, trial number PACTR201604001501493.
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Affiliation(s)
- Mphatso Dennis Phiri
- Malaria Epidemiology Group, Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi.
| | - Robert S McCann
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, USA
| | - Alinune Nathanael Kabaghe
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Tumaini Malenga
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Steven Gowelo
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Tinashe Tizifa
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Michèle van Vugt
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam-UMC, Location AMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Kamija S Phiri
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Dianne J Terlouw
- Malaria Epidemiology Group, Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, UK
| | - Eve Worrall
- Liverpool School of Tropical Medicine, Liverpool, UK
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Hii J, Hustedt J, Bangs MJ. Residual Malaria Transmission in Select Countries of Asia-Pacific Region: Old Wine in a New Barrel. J Infect Dis 2021; 223:S111-S142. [PMID: 33906222 PMCID: PMC8079134 DOI: 10.1093/infdis/jiab004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Background Despite substantial reductions in malaria burden and improvement in case management, malaria remains a major public health challenge in the Asia-Pacific region. Residual malaria transmission (RMT) is the fraction of total transmission that persists after achievement of full operational coverage with effective insecticide-treated bed nets (ITNs)/long-lasting insecticidal nets (LLINs) and/or indoor residual spray interventions. There is a critical need to standardize and share best practices for entomological, anthropological, and product development investigative protocols to meet the challenges of RMT and elimination goals. Methods A systematic review was conducted to describe when and where RMT is occurring, while specifically targeting ownership and usage of ITN/LLINs, indoor residual spray application, insecticide susceptibility of vectors, and human and vector biting behavior, with a focus on nighttime activities. Results Sixty-six publications from 1995 to present met the inclusion criteria for closer review. Associations between local vector control coverage and use with behaviors of human and mosquito vectors varied by locality and circumstance. Consequently, the magnitude of RMT is insufficiently studied and analyzed with sparse estimates of individual exposure in communities, insufficient or incomplete observations of ITN/LLIN use, and the local human population movement into and from high-risk areas. Conclusions This review identified significant gaps or deficiencies that require urgent attention, namely, developing standardized procedures and methods to estimate risk exposure beyond the peridomestic setting, analytical approaches to measure key human-vector interactions, and seasonal location-specific agricultural or forest use calendars, and establishing the collection of longitudinal human and vector data close in time and location.
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Affiliation(s)
- Jeffrey Hii
- Malaria Consortium Asia, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| | | | - Michael J Bangs
- Public Health and Malaria Control Department, PT Freeport Indonesia, International SOS, Jl. Kertajasa, Kuala Kencana, Papua, Indonesia.,Department of Entomology, Faculty of Agriculture, Kasertart University, Bangkok, Thailand
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Hinne IA, Attah SK, Mensah BA, Forson AO, Afrane YA. Larval habitat diversity and Anopheles mosquito species distribution in different ecological zones in Ghana. Parasit Vectors 2021; 14:193. [PMID: 33827667 PMCID: PMC8025514 DOI: 10.1186/s13071-021-04701-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/23/2021] [Indexed: 11/16/2022] Open
Abstract
Background Understanding the ecology of larval malaria and lymphatic filariasis mosquitoes in a changing environment is important in developing effective control tools or programmes. This study characterized the breeding habitats of Anopheles mosquitoes in rural communities in different ecological zones in Ghana during the dry and rainy seasons. Methods The spatio-temporal distribution, species composition, and abundance of larval Anopheles mosquitoes in breeding habitats were studied in five locations in three ecological zones of Ghana. These were Anyakpor (coastal savannah area), Duase (forest area), and Libga, Pagaza, and Kpalsogu (Sahel savannah area). Larvae were collected using standard dippers and were raised in the insectary for identification. Results Out of a total of 7984 mosquito larvae collected, 2152 (27.26%) were anophelines and were more abundant in the rainy season (70.82%) than in the dry season (29.18%). The anophelines comprised 2128 (98.88%) An. gambiae s.l., 16 (0.74%) An. rufipes, and 8 (0.37%) An. pharoensis. In the coastal savannah and forest zones, dug-out wells were the most productive habitat during the dry (1.59 larvae/dip and 1.47 larvae/dip) and rainy seasons (11.28 larvae/dip and 2.05 larvae/dip). Swamps and furrows were the most productive habitats in the Sahel savannah zone during the dry (0.25 larvae/dip) and rainy (2.14 larvae/dip) seasons, respectively. Anopheles coluzzii was the most abundant sibling species in all the ecological zones. Anopheles melas and An. arabiensis were encountered only in the coastal savannah and the Sahel savannah areas, respectively. Larval habitat types influenced the presence of larvae as well as larval density (p < 0.001). The land-use type affected the presence of Anopheles larvae (p = 0.001), while vegetation cover influenced larval density (p < 0.05). Conclusion The most productive habitats were dug-out wells in the coastal savannah and forest zones, and furrows from irrigated canals in the Sahel savannah zone. Anopheles coluzzii was the predominant vector species in all the ecological zones. The abundance of Anopheles breeding habitats and larvae were influenced by anthropogenic activities. Encouraging people whose activities create the larval habitats to become involved in larval source management such as habitat manipulation to stop mosquito breeding will be important for malaria and lymphatic filariasis control. Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04701-w.
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Affiliation(s)
- Isaac A Hinne
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Simon K Attah
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Benedicta A Mensah
- Department of Epidemiology, Noguchi Memorial Institute of Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Akua O Forson
- Department of Medical Laboratory Science, School of Biomedical and Allied Health Sciences, University of Ghana, Korle-Bu, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana.
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Kamndaya M, Mfipa D, Lungu K. Household knowledge, perceptions and practices of mosquito larval source management for malaria prevention and control in Mwanza district, Malawi: a cross-sectional study. Malar J 2021; 20:150. [PMID: 33731146 PMCID: PMC7967974 DOI: 10.1186/s12936-021-03683-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 03/05/2021] [Indexed: 11/26/2022] Open
Abstract
Background Mosquito larval source management (LSM) is a key outdoor malaria vector control strategy in rural communities in sub-Saharan Africa. Knowledge of this strategy is important for optimal design and implementation of effective malaria control interventions in this region. This study assessed household knowledge, perceptions and practices of mosquito LSM methods (draining stagnant water, larviciding, clearing grass/bushes and clean environment). Methods A cross-sectional design was used whereby 479 households were selected using two-stage sampling in Mwanza district, Malawi. A household questionnaire was administered to an adult member of the house. Respondents were asked questions on knowledge, perceptions and practices of mosquito LSM methods. Multivariable logistic regression model was used to identify factors associated with high-level knowledge of mosquito LSM methods. Results Majority of the respondents (64.5%) had high-level knowledge of mosquito LSM methods. Specifically, 63.7% (200/314) had positive perceptions about draining stagnant water, whereas 95.3% (223/234) practiced clean environment for malaria control and 5.2% had knowledge about larviciding. Compared to respondents with primary education, those with secondary education were more likely, whereas those without education were less likely, to have high-level knowledge of mosquito LSM methods (AOR = 3.54, 95% CI 1.45–8.63 and AOR = 0.38, 95% CI 0.23–0.64, respectively). Compared to respondents engaged in crop farming, those engaged in mixed farming (including pastoralists) and the self-employed (including business persons) were more likely to have high-level knowledge of mosquito LSM methods (AOR = 6.95, 95% CI 3.39–14.23 and AOR = 3.61, 95% CI 1.47–8.86, respectively). Respondents living in mud-walled households were less likely to have high-knowledge of mosquito LSM methods than those living in brick-walled households (AOR = 0.50, 95% CI 0.30–0.86). Conclusions A high-level knowledge of mosquito LSM methods was established. However, when designing and implementing this strategy, specific attention should be paid to the uneducated, crop farmers and those living in poor households. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03683-5.
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Affiliation(s)
- Mphatso Kamndaya
- Department of Mathematics and Statistics, School of Applied Sciences, University of Malawi, The Polytechnic, Private Bag 303, Blantyre 3, Malawi.
| | - Dumisani Mfipa
- Department of Environmental Health, School of Applied Sciences, University of Malawi, The Polytechnic, Private Bag 303, Blantyre 3, Malawi
| | - Kingsley Lungu
- Department of Environmental Health, School of Applied Sciences, University of Malawi, The Polytechnic, Private Bag 303, Blantyre 3, Malawi
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Almalik AMA, Guy Reeves R, Azrag RS. Comparison of the temporal efficacy of Aquatain surface films for the control of Anopheles arabiensis and Ochlerotatus caspius larvae from Sudan. ROYAL SOCIETY OPEN SCIENCE 2021; 8:200980. [PMID: 33972842 PMCID: PMC8074655 DOI: 10.1098/rsos.200980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 01/20/2021] [Indexed: 06/12/2023]
Abstract
Aquatain mosquito formulation (AMF) is a surfactant that spreads across the surface of water bodies to produce a monomolecular film. This study experimentally evaluates the temporal efficacy of AMF against aquatic stages of Anopheles arabiensis and Ochlerotatus caspius under laboratory conditions. Using the recommended application dose of 1 ml m-2, a large species-specific difference in the median lethal time for L3-L4 larvae was observed. The median lethal time to 50% mortality (LT50) and 90% mortality (LT90) was 1.3 h, 95% CI [1.2, 1.4] and 3.8 h, 95% CI [3.6, 4.0], respectively, for Oc. caspius. The corresponding values for An. arabiensis were 8.1 h, 95% CI [7.3, 9.0] and 59.6 h, 95% CI [48.5, 76.2]. Based on data from published laboratory studies for a total of seven mosquito species, drawn from four genera, results in the following three groups, [LT50 = 1-2 h, Culex quinquefasciatus, Ochlerotatus caspius] [LT50 = 8-24, hours, Anopheles minimus, Anopheles arabiensis, Anopheles gambiae s.s.] and [LT50 = 72-143 h, Anopheles stephensi, Aedes aegypti]. In all experiments, 100% mortality was achieved given sufficient time. The potential relevance of mortality rate estimates, in the context of other studies, on the use of monomolecular films for the control of malaria and arbovirus diseases is discussed.
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Affiliation(s)
- Alaa Mahmoud Ali Almalik
- Vector Genetics and Control Laboratory, Department of Zoology, Faculty of Science, University of Khartoum, Sudan
| | - R. Guy Reeves
- Max Planck Institute for Evolutionary Biology, Plön Germany
| | - Rasha Siddig Azrag
- Vector Genetics and Control Laboratory, Department of Zoology, Faculty of Science, University of Khartoum, Sudan
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28
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Chaccour C. Veterinary endectocides for malaria control and elimination: prospects and challenges. Philos Trans R Soc Lond B Biol Sci 2020; 376:20190810. [PMID: 33357062 DOI: 10.1098/rstb.2019.0810] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Residual transmission is the persistence of malaria transmission after scale-up of appropriate vector control tools and is one of the key challenges for malaria elimination today. Although long associated with outdoor biting, other mosquito behaviours such as partly feeding upon animals contribute greatly to sustaining transmission. Peri-domestic livestock can be used as decoy to protect humans from blood-seeking vectors but this approach often leads to an increased malaria risk in a phenomenon known as zoopotentiation. Treating the said livestock with drugs capable of killing intestinal parasites as well as mosquitoes that feed upon them has the potential to tackle malaria through a previously unexplored mechanism. The advantages and challenges associated with this approach are briefly discussed here. Numerous references are purposely provided. This article is part of the theme issue 'Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Carlos Chaccour
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Rosello 132, 5ª 2ª, 08036 Barcelona, Spain.,Ifakara Health Institute, Off Mlabani Passage, PO Box 53, Ifakara, United Republic of Tanzania.,Faculty of Medicine, Universidad de Navarra, Calle de Irunlarrea 1, 31008 Pamplona, Spain
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Mlacha YP, Chaki PP, Muhili A, Massue DJ, Tanner M, Majambere S, Killen GF, Govella NJ. Reduced human-biting preferences of the African malaria vectors Anopheles arabiensis and Anopheles gambiae in an urban context: controlled, competitive host-preference experiments in Tanzania. Malar J 2020; 19:418. [PMID: 33218346 PMCID: PMC7678205 DOI: 10.1186/s12936-020-03495-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/11/2020] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Host preference is a critical determinant of human exposure to vector-borne infections and the impact of vector control interventions. Widespread use of long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) across sub-Saharan Africa, which protect humans against mosquitoes, may select for altered host preference traits of malaria vectors over the long term. Here, the host preferences of Anopheles arabiensis and Anopheles gambiae sensu stricto (s.s.) were experimentally assessed in the field, using direct host-preference assays in two distinct ecological settings in Tanzania. METHODS Eight Ifakara Tent Trap (ITT), four baited with humans and four with bovine calves, were simultaneously used to catch malaria vectors in open field sites in urban and rural Tanzania. The numbers of mosquitoes collected in human-baited traps versus calf-baited traps were used to estimate human feeding preference for each site's vector species. RESULTS The estimated proportion [95% confidence interval (CI)] of mosquitoes attacking humans rather than cattle was 0.60 [0.40, 0.77] for An. arabiensis in the rural setting and 0.61 [0.32, 0.85] for An. gambiae s.s. in the urban setting, indicating no preference for either host in both cases (P = 0.32 and 0.46, respectively) and no difference in preference between the two (Odds Ratio (OR) [95%] = 0.95 [0.30, 3.01], P = 0.924). However, only a quarter of An. arabiensis in the urban setting attacked humans (0.25 [0.09, 0.53]), indicating a preference for cattle that approached significance (P = 0.08). Indeed, urban An. arabiensis were less likely to attack humans rather than cattle when compared to the same species in the rural setting (OR [95%] = 0.21 [0.05, 0.91], P = 0.037). CONCLUSION Urban An. arabiensis had a stronger preference for cattle than the rural population and urban An. gambiae s.s. showed no clear preference for either humans or cattle. In the urban setting, both species exhibited stronger tendencies to attack cattle than previous studies of the same species in rural contexts. Cattle keeping may, therefore, particularly limit the impact of human-targeted vector control interventions in Dar es Salaam and perhaps in other African towns and cities.
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Affiliation(s)
- Yeromin P Mlacha
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania.
- Swiss Tropical and Public Health Institute, Basel, Switzerland.
- University of Basel, Basel, Switzerland.
| | - Prosper P Chaki
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania
- The Pan-African Mosquito Control Association (PAMCA), KEMRI Headquarters, Mbagathi Road, Nairobi, 54840-00200, Nairobi, Kenya
| | - Athuman Muhili
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania
| | - Dennis J Massue
- Univerity of Dar Es Salaam, Mbeya College of Health and Allied Sciences, P.O. Box 608, Mbeya, United Republic of Tanzania
- Amani Research Centre, National Institute for Medical Research, P.O. Box 81, Muheza-Tanga, United Republic of Tanzania
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Silas Majambere
- The Pan-African Mosquito Control Association (PAMCA), KEMRI Headquarters, Mbagathi Road, Nairobi, 54840-00200, Nairobi, Kenya
| | - Gerry F Killen
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania
- Liverpool School of Tropical Medicine, Vector Biology Department, Pembroke Place, Liverpool, L3 5QA, UK
- School of Biological, Earth & Environmental Sciences and Environmental Research Institute, University College Cork, Cork, Republic of Ireland
| | - Nicodem J Govella
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania
- The Nelson Mandela, African Institution of Science and Technology, The School of Life Science and Bio-Engineering (LISBE), P.O.BOX 447, Tengeru, Arusha, United Republic of Tanzania
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Are Individuals Willing to Pay for Community-Based Eco-Friendly Malaria Vector Control Strategies? A Case of Mosquito Larviciding Using Plant-Based Biopesticides in Kenya. SUSTAINABILITY 2020. [DOI: 10.3390/su12208552] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This study was carried out to assess individuals’ willingness to pay (WTP) for UZIMAX, a novel plant-based biopesticide developed for malaria vector control. The biopesticide is estimated to kill up to 100% of Anopheles larvae within 48 h of application and poses no risks to human health and the environment. However, scaling-up of its adoption requires clear evidence of its acceptance by individuals in malaria-prone areas. We conducted Becker-DeGroot-Marschak (BDM) revealed preference auctions with 204 participants to determine their willingness to pay (WTP) for community-based application of the biopesticide to control malaria vectors. Nearly all participants were willing to pay at the lowest bid price of the biopesticide, and the majority of them expressed great interest in pooling resources to facilitate biopesticide application. Household per capita income and building capacity of households through training significantly increased WTP. These findings imply high adoption potential of the technology and the need to devise inclusive policy tools, especially those that enhance collective action, resource mobilization and capacity building to empower both men and women and stimulate investment in eco-friendly technologies for malaria prevention. Financial and labor resource mechanisms managed by the community could potentially spur adoption of the biopesticides, and in turn, generate health, environmental and economic benefits to households in malaria-prone communities.
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Emergence of behavioural avoidance strategies of malaria vectors in areas of high LLIN coverage in Tanzania. Sci Rep 2020; 10:14527. [PMID: 32883976 PMCID: PMC7471940 DOI: 10.1038/s41598-020-71187-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 08/10/2020] [Indexed: 01/20/2023] Open
Abstract
Despite significant reductions in malaria transmission across Africa since 2000, progress is stalling. This has been attributed to the development of insecticide resistance and behavioural adaptations in malaria vectors. Whilst insecticide resistance has been widely investigated, there is poorer understanding of the emergence, dynamics and impact of mosquito behavioural adaptations. We conducted a longitudinal investigation of malaria vector host choice over 3 years and resting behaviour over 4 years following a mass long-lasting insecticidal nets (LLINs) distribution in Tanzania. By pairing observations of mosquito ecology with environmental monitoring, we quantified longitudinal shifts in host-choice and resting behaviour that are consistent with adaptation to evade LLINs. The density of An. funestuss.l., declined significantly through time. In tandem, An. arabiensis and An. funestuss.l. exhibited an increased rate of outdoor relative to indoor resting; with An. arabiensis reducing the proportion of blood meals taken from humans in favour of cattle. By accounting for environmental variation, this study detected clear evidence of intra-specific shifts in mosquito behaviour that could be obscured in shorter-term or temporally-coarse surveys. This highlights the importance of mosquito behavioural adaptations to vector control, and the value of longer-term behavioural studies.
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Vector control for malaria elimination in Botswana: progress, gaps and opportunities. Malar J 2020; 19:301. [PMID: 32843037 PMCID: PMC7449088 DOI: 10.1186/s12936-020-03375-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 08/13/2020] [Indexed: 12/29/2022] Open
Abstract
Botswana has in the recent past 10 years made tremendous progress in the control of malaria and this informed re-orientation from malaria control to malaria elimination by the year 2020. This progress is attributed to improved case management, and scale-up of key vector control interventions; indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs). However, insecticide resistance, outdoor biting and resting, and predisposing human behaviour, such as staying outdoors or sleeping outdoors without the use of protective measures, pose a challenge to the realization of the full impact of LLINs and IRS. This, together with the paucity of entomological data, inadequate resources and weak community participation for vector control programme implementation delayed attainment of Botswana’s goal of malaria elimination. Also, the Botswana National Malaria Programme (NMP) experiences the lack of intersectoral collaborations and operational research for evidence-based decision making. This case study focuses on the vector control aspect of malaria elimination by identifying challenges and explores opportunities that could be taken advantage of to benefit the NMP to optimize and augment the current vector control interventions to achieve malaria elimination by the year 2030 as per the Global Technical Strategy for Malaria 2016–2030 targets. The authors emphasize the need for timely and quality entomological surveillance, operational research and integrated vector management.
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Monroe A, Msaky D, Kiware S, Tarimo BB, Moore S, Haji K, Koenker H, Harvey S, Finda M, Ngowo H, Mihayo K, Greer G, Ali A, Okumu F. Patterns of human exposure to malaria vectors in Zanzibar and implications for malaria elimination efforts. Malar J 2020; 19:212. [PMID: 32571338 PMCID: PMC7310102 DOI: 10.1186/s12936-020-03266-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 05/23/2020] [Indexed: 11/10/2022] Open
Abstract
Background Zanzibar provides a good case study for malaria elimination. The islands have experienced a dramatic reduction in malaria burden since the introduction of effective vector control interventions and case management. Malaria prevalence has now been maintained below 1% for the past decade and the islands can feasibly aim for elimination. Methods To better understand factors that may contribute to remaining low-level malaria transmission in Zanzibar, layered human behavioural and entomological research was conducted between December 2016 and December 2017 in 135 randomly selected households across six administrative wards. The study included: (1) household surveys, (2) structured household observations of nighttime activity and sleeping patterns, and (3) paired indoor and outdoor mosquito collections. Entomological and human behavioural data were integrated to provide weighted estimates of exposure to vector bites, accounting for proportions of people indoors or outdoors, and protected by insecticide-treated nets (ITNs) each hour of the night. Results Overall, 92% of female Anopheles mosquitoes were caught in the rainy season compared to 8% in the dry season and 72% were caught outdoors compared to 28% indoors. For individual ITN users, ITNs prevented an estimated two-thirds (66%) of exposure to vector bites and nearly three quarters (73%) of residual exposure was estimated to occur outdoors. Based on observed levels of ITN use in the study sites, the population-wide mean personal protection provided by ITNs was 42%. Discussion/conclusions This study identified gaps in malaria prevention in Zanzibar with results directly applicable for improving ongoing programme activities. While overall biting risk was low, the most notable finding was that current levels of ITN use are estimated to prevent less than half of exposure to malaria vector bites. Variation in ITN use across sites and seasons suggests that additional gains could be made through targeted social and behaviour change interventions. However, even for ITN users, gaps in protection remain, with a majority of exposure to vector bites occurring outdoors before going to sleep. Supplemental interventions targeting outdoor exposure to malaria vectors, and groups that may be at increased risk of exposure to malaria vectors, should be explored.
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Affiliation(s)
- April Monroe
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA. .,University of Basel, Basel, Switzerland. .,Swiss Tropical and Public Health Institute, Basel, Switzerland.
| | - Dickson Msaky
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Samson Kiware
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Brian B Tarimo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Sarah Moore
- University of Basel, Basel, Switzerland.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Khamis Haji
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - Hannah Koenker
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
| | - Steven Harvey
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Marceline Finda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Halfan Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Kimberly Mihayo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - George Greer
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar Es Salaam, Tanzania
| | - Abdullah Ali
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - Fredros Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Republic of South Africa.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
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Semifield Evaluation of Improved Passive Outdoor Host Seeking Device (POHD) for Outdoor Control of Anopheles arabiensis Mosquitoes. ScientificWorldJournal 2020; 2020:8938309. [PMID: 32547328 PMCID: PMC7271259 DOI: 10.1155/2020/8938309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 03/07/2020] [Accepted: 04/13/2020] [Indexed: 12/03/2022] Open
Abstract
Despite the considerable progress made so far, the effectiveness and mass application of odour-baited outdoor mosquito control devices in pipelines is limited by several factors. These include the design and size of the devices, optimal placement of attractive blends, and nature of materials into which the blends are impregnated. The primary aim of this study was to manipulate these factors to improve the attractiveness of our recently developed passive outdoor host seeking device (POHD) to outdoor biting Anopheles arabiensis. Specifically, the study aimed to determine optimal placement of odour blends and killing bioactives in POHD for maximum attraction and killing of An. arabiensis and to assess the effects of blend types, formulation, and residual activity on attractiveness of the POHD to An. arabiensis. The POHDs baited with attractive blends, carbon dioxide (CO2), and bendiocarb-treated electrostatic netting were placed either towards the top or bottom openings, and other modifications were exposed to An. arabiensis under the semifield system at Ifakara Health Institute (IHI). Each night, a total of 100 starved female, 3–7-day-old, semifield reared An. arabiensis mosquitoes were released, collected the next morning (alive or dead), counted, and recorded. Live mosquitoes were maintained in the semifield insectary and monitored for 24 hours mortality. Each treatment combination of the POHD was tested in three replicates. Overall, the results indicated that the proportion of mosquitoes attracted to and killed in the POHD varied with position of attractants and killing agent (bendiocarb). The POHD with bottom placed attractants and bendiocarb attracted and killed higher proportion of mosquitoes compared to the POHD with top placed attractants and bendiocarb. The highest mortalities were observed when the POHD was baited with a combination of attractive blends and CO2. Moreover, the residual activity of attractive blends applied inside POHD varied with type and formulation of attractive blend. The POHD packed with Mbita and Ifakara blend in microencapsulated pellets (granules) attracted higher proportion of mosquitoes than that baited with soaked nylon-strip formulation of either blends. Interestingly, POHD baited with Mbita blend in microencapsulated pellets (granules) formulation attracted and killed higher proportion of mosquitoes (>90%) than that baited with Ifakara blend even 9 months after application. Conclusively, the POHD remained effective for a relatively longer period of time when baited with bottom placed synthetic blends and CO2 combination, thus warranting further trials under real life situations.
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Monroe A, Moore S, Okumu F, Kiware S, Lobo NF, Koenker H, Sherrard-Smith E, Gimnig J, Killeen GF. Methods and indicators for measuring patterns of human exposure to malaria vectors. Malar J 2020; 19:207. [PMID: 32546166 PMCID: PMC7296719 DOI: 10.1186/s12936-020-03271-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 05/29/2020] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Effective targeting and evaluation of interventions that protect against adult malaria vectors requires an understanding of how gaps in personal protection arise. An improved understanding of human and mosquito behaviour, and how they overlap in time and space, is critical to estimating the impact of insecticide-treated nets (ITNs) and determining when and where supplemental personal protection tools are needed. Methods for weighting estimates of human exposure to biting Anopheles mosquitoes according to where people spend their time were first developed over half a century ago. However, crude indoor and outdoor biting rates are still commonly interpreted as indicative of human-vector contact patterns without any adjustment for human behaviour or the personal protection effects of ITNs. MAIN TEXT A small number of human behavioural variables capturing the distribution of human populations indoors and outdoors, whether they are awake or asleep, and if and when they use an ITN over the course of the night, can enable a more accurate representation of human biting exposure patterns. However, to date no clear guidance is available on what data should be collected, what indicators should be reported, or how they should be calculated. This article presents an integrated perspective on relevant indicators of human-vector interactions, the critical entomological and human behavioural data elements required to quantify human-vector interactions, and recommendations for collecting and analysing such data. CONCLUSIONS If collected and used consistently, this information can contribute to an improved understanding of how malaria transmission persists in the context of current intervention tools, how exposure patterns may change as new vector control tools are introduced, and the potential impact and limitations of these tools. This article is intended to consolidate understanding around work on this topic to date and provide a consistent framework for building upon it. Additional work is needed to address remaining questions, including further development and validation of methods for entomological and human behavioural data collection and analysis.
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Affiliation(s)
- April Monroe
- Johns Hopkins Center for Communication Programs, PMI VectorWorks Project, Baltimore, MD, USA.
- University of Basel, Basel, Switzerland.
- Swiss Tropical and Public Health Institute, Basel, Switzerland.
| | - Sarah Moore
- University of Basel, Basel, Switzerland
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Fredros Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Republic of South Africa
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Samson Kiware
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Neil F Lobo
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Hannah Koenker
- Johns Hopkins Center for Communication Programs, PMI VectorWorks Project, Baltimore, MD, USA
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - John Gimnig
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Gerry F Killeen
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- School of Biological, Earth & Environmental Sciences and Environmental Research Institute, University College Cork, Cork, Republic of Ireland
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Indoor and outdoor residual spraying of a novel formulation of deltamethrin K-Othrine® (Polyzone) for the control of simian malaria in Sabah, Malaysia. PLoS One 2020; 15:e0230860. [PMID: 32413033 PMCID: PMC7228059 DOI: 10.1371/journal.pone.0230860] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 03/10/2020] [Indexed: 11/19/2022] Open
Abstract
Since 2000, human malaria cases in Malaysia were rapidly reduced with the use of insecticides in Indoor Residual Spray (IRS) and Long-Lasting Insecticide Net (LLIN). Unfortunately, monkey malaria in humans has shown an increase especially in Sabah and Sarawak. The insecticide currently used in IRS is deltamethrin K-Othrine® WG 250 wettable granule, targeting mosquitoes that rest and feed indoor. In Sabah, the primary vector for knowlesi malaria is An. balabacensis a species known to bite outdoor. This study evaluates an alternative method, the Outdoor Residual Spray (ORS) using a novel formulation of deltamethrin K-Othrine® (PolyZone) to examine it suitability to control knowlesi malaria vector in Sabah, compared to the current method. The study was performed at seven villages in Sabah having similar type of houses (wood, bamboo and concrete). Houses were sprayed with deltamethrin K-Othrine® (PolyZone) at two different dosages, 25 mg/m2 and 30 mg/m2 and deltamethrin K-Othrine® WG 250 wettable granule at 25 mg/m2, sprayed indoor and outdoor. Residual activity on different walls was assessed using standard cone bioassay techniques. For larval surveillances, potential breeding sites were surveyed. Larvae were collected and identified, pre and post spraying. Adult survey was done using Human Landing Catch (HLC) performed outdoor and indoor. Detection of malaria parasite in adults was conducted via microscopy and molecular methods. Deltamethrin K-Othrine® (PolyZone) showed higher efficacy when sprayed outdoor. The efficacy was found varied when sprayed on different types of wall surfaces. Deltamethrin K-Othrine® (PolyZone) at 25 mg/m2 was the most effective with regards to ability to high mortality and effective knock down (KD). The vector population was reduced significantly post-spraying and reduction in breeding sites as well. The number of simian malaria infected vector, human and simian malaria transmission were also greatly reduced.
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Masalu JP, Finda M, Killeen GF, Ngowo HS, Pinda PG, Okumu FO. Creating mosquito-free outdoor spaces using transfluthrin-treated chairs and ribbons. Malar J 2020; 19:109. [PMID: 32156280 PMCID: PMC7063784 DOI: 10.1186/s12936-020-03180-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 03/02/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Residents of malaria-endemic communities spend several hours outdoors performing different activities, e.g. cooking, story-telling or eating, thereby exposing themselves to potentially-infectious mosquitoes. This compromises effectiveness of indoor interventions, notably long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS). This study characterized common peri-domestic spaces in rural south-eastern Tanzania, and assessed protective efficacy against mosquitoes of hessian fabric mats and ribbons treated with the spatial repellent, transfluthrin, and fitted to chairs and outdoor kitchens, respectively. METHODS Two hundred households were surveyed, and their most-used peri-domestic spaces physically characterized. Protective efficacies of locally-made transfluthrin-emanating chairs and hessian ribbons were tested in outdoor environments of 28 households in dry and wet seasons, using volunteer-occupied exposure-free double net traps. CDC light traps were used to estimate host-seeking mosquito densities within open-structure outdoor kitchens. Field-collected Anopheles arabiensis and Anopheles funestus mosquitoes were exposed underneath the chairs to estimate 24 h-mortality. Finally, The World Health Organization insecticide susceptibility tests were conducted on wild-caught Anopheles from the villages. RESULTS Approximately half (52%) of houses had verandas. Aside from these verandas, most houses also had peri-domestic spaces where residents stayed most times (67% of houses with verandas and 94% of non-veranda houses). Two-thirds of these spaces were sited under trees, and only one third (34.4%) were built-up. The outdoor structures were usually makeshift kitchens having roofs and partial walls. Transfluthrin-treated chairs reduced outdoor-biting An. arabiensis densities by 70-85%, while transfluthrin-treated hessian ribbons fitted to the outdoor kitchens caused 77-81% reduction in the general peri-domestic area. Almost all the field-collected An. arabiensis (99.4%) and An. funestus (100%) exposed under transfluthrin-treated chairs died. The An. arabiensis were susceptible to non-pyrethroids (pirimiphos methyl and bendiocarb), but resistant to pyrethroids commonly used on LLINs (deltamethrin and permethrin). CONCLUSION Most houses had actively-used peri-domestic outdoor spaces where exposure to mosquitoes occurred. The transfluthrin-treated chairs and ribbons reduced outdoor-biting malaria vectors in these peri-domestic spaces, and also elicited significant mortality among pyrethroid-resistant field-caught malaria vectors. These two new prototype formats for transfluthrin emanators, if developed further, may constitute new options for complementing LLINs and IRS with outdoor protection against malaria and other mosquito-borne pathogens in areas where peri-domestic human activities are common.
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Affiliation(s)
- John P Masalu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.
- School of Life Science and Biotechnology, Nelson Mandela African Institution of Science and Technology, Arusha, United Republic of Tanzania.
| | - Marceline Finda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- School of Public Health, University of the Witwatersrand, Parktown, Johannesburg, Republic of South Africa
| | - Gerry F Killeen
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Polius G Pinda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- School of Life Science and Biotechnology, Nelson Mandela African Institution of Science and Technology, Arusha, United Republic of Tanzania
- School of Public Health, University of the Witwatersrand, Parktown, Johannesburg, Republic of South Africa
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
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Orsborne J, Mohammed AR, Jeffries CL, Kristan M, Afrane YA, Walker T, Yakob L. Evidence of extrinsic factors dominating intrinsic blood host preferences of major African malaria vectors. Sci Rep 2020; 10:741. [PMID: 31959845 PMCID: PMC6971008 DOI: 10.1038/s41598-020-57732-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 12/02/2019] [Indexed: 11/20/2022] Open
Abstract
One of the key determinants of a haematophagous vector’s capacity to transmit pathogens is its selection of which host to secure a blood meal from. This choice is influenced by both intrinsic (genetic) and extrinsic (environmental) factors, but little is known of their relative contributions. Blood fed Anopheles mosquitoes were collected from a malaria endemic village in Ghana. Collections were conducted across a range of different host availabilities and from both indoor and outdoor locations. These environmental factors were shown to impact dramatically the host choice of caught malaria vectors: mosquitoes caught indoors were ten-fold more likely to have sourced their blood meal from humans; and a halving in odds of being human-fed was found for mosquitoes caught only 25 m from the centre of the village. For the first time, we demonstrate that anthropophagy was better explained by extrinsic factors (namely, local host availability and indoor/outdoor trapping location) than intrinsic factors (namely, the (sibling) species of the mosquito caught) (respective Akaike information criterion estimates: 243.0 versus 359.8). Instead of characterizing biting behaviour on a taxonomic level, we illustrate the importance of assessing local entomology. Accounting for this behavioural plasticity is important, both in terms of measuring effectiveness of control programmes and in informing optimal disease control strategies.
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Affiliation(s)
- James Orsborne
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Abdul Rahim Mohammed
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Korle Bu, Accra, Ghana
| | - Claire L Jeffries
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Mojca Kristan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Yaw A Afrane
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Korle Bu, Accra, Ghana
| | - Thomas Walker
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Laith Yakob
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
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Musiime AK, Smith DL, Kilama M, Rek J, Arinaitwe E, Nankabirwa JI, Kamya MR, Conrad MD, Dorsey G, Akol AM, Staedke SG, Lindsay SW, Egonyu JP. Impact of vector control interventions on malaria transmission intensity, outdoor vector biting rates and Anopheles mosquito species composition in Tororo, Uganda. Malar J 2019; 18:445. [PMID: 31881898 PMCID: PMC6935116 DOI: 10.1186/s12936-019-3076-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 12/14/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) and indoor residual spraying of insecticide (IRS) are widely recommended for the prevention of malaria in endemic regions. Data from human landing catches provide information on the impact of vector control on vector populations. Here, malaria transmission indoors and outdoors, before and after mass deployment of LLINs and IRS in Uganda was compared. METHODS The study took place in Tororo district, a historically high transmission area where universal LLIN distribution was conducted in November 2013 and May 2017 and 6 rounds of IRS implemented from December 2014 to July 2018. Human landing catches were performed in 8 houses monthly from October 2011 to September 2012 (pre-intervention period) and every 4 weeks from November 2017 to October 2018 (post-intervention period). Mosquitoes were collected outdoors from 18:00 to 22:00 h and indoors from 18:00 to 06:00 h. Female Anopheles were tested for the presence of Plasmodium falciparum sporozoites and species identification performed using gross dissection and polymerase chain reaction (PCR). RESULTS The interventions were associated with a decline in human biting rate from 19.6 to 2.3 female Anopheles mosquitoes per house per night (p < 0.001) and annual entomological inoculation rate from 129 to 0 infective bites per person per year (p < 0.001). The proportion of mosquitoes collected outdoors increased from 11.6 to 49.4% (p < 0.001). Prior to the interventions the predominant species was Anopheles gambiae sensu stricto (s.s.), which comprised an estimated 76.7% of mosquitoes. Following the interventions, the predominant species was Anopheles arabiensis, which comprised 99.5% of mosquitoes, with almost complete elimination of An. gambiae s.s. (0.5%). CONCLUSIONS Mass distribution of LLINs and 6 rounds of IRS dramatically decreased vector density and sporozoite rate resulting in a marked reduction in malaria transmission intensity in a historically high transmission site in Uganda. These changes were accompanied by a shift in vector species from An. gambiae s.s. to An. arabiensis and a relative increase in outdoor biting.
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Affiliation(s)
- Alex K Musiime
- Infectious Diseases Research Collaboration, Kampala, Uganda. .,Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, Makerere University, Kampala, Uganda.
| | - David L Smith
- Institute for Health Metrics & Evaluation, University of Washington, Seattle, WA, USA
| | - Maxwell Kilama
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - John Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Melissa D Conrad
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Grant Dorsey
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Anne M Akol
- Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Sarah G Staedke
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | | | - James P Egonyu
- Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, Makerere University, Kampala, Uganda.,International Center of Insect Physiology and Ecology, Nairobi, Kenya
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Ahorlu CS, Adongo P, Koenker H, Zigirumugabe S, Sika-Bright S, Koka E, Tabong PTN, Piccinini D, Segbaya S, Olapeju B, Monroe A. Understanding the gap between access and use: a qualitative study on barriers and facilitators to insecticide-treated net use in Ghana. Malar J 2019; 18:417. [PMID: 31831004 PMCID: PMC6909499 DOI: 10.1186/s12936-019-3051-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 12/02/2019] [Indexed: 11/15/2022] Open
Abstract
Background Mass and continuous distribution channels have significantly increased access to insecticide-treated nets (ITNs) in Ghana since 2000. Despite these gains, a large gap remains between ITN access and use. Methods A qualitative research study was carried out to explore the individual and contextual factors influencing ITN use among those with access in three sites in Ghana. Eighteen focus group discussions, and free listing and ranking activities were carried out with 174 participants; seven of those participants were selected for in-depth case study. Focus group discussions and case study interviews were audio-recorded, transcribed verbatim, and analysed thematically. Results ITN use, as described by study participants, was not binary; it varied throughout the night, across seasons, and over time. Heat was the most commonly cited barrier to consistent ITN use and contributed to low reported ITN use during the dry season. Barriers to ITN use throughout the year included skin irritation; lack of airflow in the sleeping space; and, in some cases, a lack of information on the connection between the use of ITNs and malaria prevention. Falling ill or losing a loved one to malaria was the most powerful motivator for consistent ITN use. Participants also discussed developing a habit of ITN use and the economic benefit of prevention over treatment as facilitating factors. Participants reported gender differences in ITN use, noting that men were more likely than women and children to stay outdoors late at night and more likely to sleep outdoors without an ITN. Conclusion The study results suggest the greatest gains in ITN use among those with access could be made by promoting consistent use throughout the year among occasional and seasonal users. Opportunities for improving communication messages, such as increasing the time ITNs are aired before first use, as well as structural approaches to enhance the usability of ITNs in challenging contexts, such as promoting solutions for outdoor ITN use, were identified from this work. The information from this study can be used to inform social and behaviour change messaging and innovative approaches to closing the ITN use gap in Ghana.
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Affiliation(s)
- Collins Stephen Ahorlu
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Philip Adongo
- Department of Social and Behavioral Science, School of Public Health, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Hannah Koenker
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
| | - Sixte Zigirumugabe
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Accra, Ghana
| | - Solomon Sika-Bright
- Department of Sociology and Anthropology, University of Cape Coast, Cape Coast, Ghana
| | - Eric Koka
- Department of Sociology and Anthropology, University of Cape Coast, Cape Coast, Ghana
| | - Philip Teg-Nefaah Tabong
- Department of Social and Behavioral Science, School of Public Health, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Danielle Piccinini
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
| | | | - Bolanle Olapeju
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
| | - April Monroe
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA. .,Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
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Sanou A, Moussa Guelbéogo W, Nelli L, Hyacinth Toé K, Zongo S, Ouédraogo P, Cissé F, Mirzai N, Matthiopoulos J, Sagnon N, Ferguson HM. Evaluation of mosquito electrocuting traps as a safe alternative to the human landing catch for measuring human exposure to malaria vectors in Burkina Faso. Malar J 2019; 18:386. [PMID: 31791336 PMCID: PMC6889701 DOI: 10.1186/s12936-019-3030-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 11/24/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Measuring human exposure to mosquito bites is a crucial component of vector-borne disease surveillance. For malaria vectors, the human landing catch (HLC) remains the gold standard for direct estimation of exposure. This method, however, is controversial since participants risk exposure to potentially infected mosquito bites. Recently an exposure-free mosquito electrocuting trap (MET) was developed to provide a safer alternative to the HLC. Early prototypes of the MET performed well in Tanzania but have yet to be tested in West Africa, where malaria vector species composition, ecology and behaviour are different. The performance of the MET relative to HLC for characterizing mosquito vector population dynamics and biting behaviour in Burkina Faso was evaluated. METHODS A longitudinal study was initiated within 12 villages in Burkina Faso in October 2016. Host-seeking mosquitoes were sampled monthly using HLC and MET collections over 14 months. Collections were made at 4 households on each night, with METs deployed inside and outside at 2 houses, and HLC inside and outside at another two. Malaria vector abundance, species composition, sporozoite rate and location of biting (indoor versus outdoor) were recorded. RESULTS In total, 41,800 mosquitoes were collected over 324 sampling nights, with the major malaria vector being Anopheles gambiae sensu lato (s.l.) complex. Overall the MET caught fewer An. gambiae s.l. than the HLC (mean predicted number of 0.78 versus 1.82 indoors, and 1.05 versus 2.04 outdoors). However, MET collections gave a consistent representation of seasonal dynamics in vector populations, species composition, biting behaviour (location and time) and malaria infection rates relative to HLC. As the relative performance of the MET was somewhat higher in outdoor versus indoor settings, this trapping method slightly underestimated the proportion of bites preventable by LLINs compared to the HLC (MET = 82.08%; HLC = 87.19%). CONCLUSIONS The MET collected proportionately fewer mosquitoes than the HLC. However, estimates of An. gambiae s.l. density in METs were highly correlated with HLC. Thus, although less sensitive, the MET is a safer alternative than the HLC. Its use is recommended particularly for sampling vectors in outdoor environments where it is most sensitive.
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Affiliation(s)
- Antoine Sanou
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK.
- Centre National de Recherche et de Formation sur le Paludisme, Av. Kunda nyooré, PO Box 2208, Ouagadougou, Burkina Faso.
| | - W Moussa Guelbéogo
- Centre National de Recherche et de Formation sur le Paludisme, Av. Kunda nyooré, PO Box 2208, Ouagadougou, Burkina Faso
| | - Luca Nelli
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
| | - K Hyacinth Toé
- Centre National de Recherche et de Formation sur le Paludisme, Av. Kunda nyooré, PO Box 2208, Ouagadougou, Burkina Faso
| | - Soumanaba Zongo
- Centre National de Recherche et de Formation sur le Paludisme, Av. Kunda nyooré, PO Box 2208, Ouagadougou, Burkina Faso
| | - Pierre Ouédraogo
- Centre National de Recherche et de Formation sur le Paludisme, Av. Kunda nyooré, PO Box 2208, Ouagadougou, Burkina Faso
| | - Fatoumata Cissé
- Centre National de Recherche et de Formation sur le Paludisme, Av. Kunda nyooré, PO Box 2208, Ouagadougou, Burkina Faso
| | - Nosrat Mirzai
- Bioelectronics Units, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
| | - Jason Matthiopoulos
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
| | - N'falé Sagnon
- Centre National de Recherche et de Formation sur le Paludisme, Av. Kunda nyooré, PO Box 2208, Ouagadougou, Burkina Faso
| | - Heather M Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
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Biting patterns of malaria vectors of the lower Shire valley, southern Malawi. Acta Trop 2019; 197:105059. [PMID: 31194960 DOI: 10.1016/j.actatropica.2019.105059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 12/13/2022]
Abstract
Assessing the biting behaviour of malaria vectors plays an integral role in understanding the dynamics of malaria transmission in a region. Biting times and preference for biting indoors or outdoors varies among mosquito species and across regions. These behaviours may also change over time in response to vector control measures such as long-lasting insecticidal nets (LLINs). Data on these parameters can provide the sites and times at which different interventions would be effective for vector control. This study assessed the biting patterns of malaria vectors in Chikwawa district, southern Malawi. The study was conducted during the dry and wet seasons in 2016 and 2017, respectively. In each season, mosquitoes were collected indoors and outdoors for 24 nights in six houses per night using the human landing catch. Volunteers were organized into six teams of two individuals, whereby three teams collected mosquitoes indoors and the other three collected mosquitoes outdoors each night, and the teams were rotated among twelve houses. All data were analyzed using Poisson log-linear models. The most abundant species were Anopheles gambiae sensu lato (primarily An. arabiensis) and An. funestus s.l. (exclusively An. funestus s.s.). During the dry season, the biting activity of An. gambiaes.l. was constant outdoors across the categorized hours (18:00 h to 08:45 h), but highest in the late evening hours (21:00 h to 23:45 h) during the wet season. The biting activity of An. funestus s.l. was highest in the late evening hours (21:00 h to 23:45 h) during the dry season and in the late night hours (03:00 h to 05:45 h) during the wet season. Whereas the number of An. funestuss.l. biting was constant (P = 0.662) in both seasons, that of An. gambiaes.l. was higher during the wet season than in the dry season (P = 0.001). Anopheles gambiae s.l. was more likely to bite outdoors than indoors in both seasons. During the wet season, An. funestus s.l. was more likely to bite indoors than outdoors but during the dry season, the bites were similar both indoors and outdoors. The biting activity that occurred in the early and late evening hours, both indoors and outdoors coincides with the times at which individuals may still be awake and physically active, and therefore unprotected by LLINs. Additionally, a substantial number of anopheline bites occurred outdoors. These findings imply that LLINs would only provide partial protection from malaria vectors, which would affect malaria transmission in this area. Therefore, protection against bites by malaria mosquitoes in the early and late evening hours is essential and can be achieved by designing interventions that reduce vector-host contacts during this period.
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Odero JO, Fillinger U, Rippon EJ, Masiga DK, Weetman D. Using sibship reconstructions to understand the relationship between larval habitat productivity and oviposition behaviour in Kenyan Anopheles arabiensis. Malar J 2019; 18:286. [PMID: 31443645 PMCID: PMC6708163 DOI: 10.1186/s12936-019-2917-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 08/17/2019] [Indexed: 11/10/2022] Open
Abstract
Background Strategies for combatting residual malaria by targeting vectors outdoors are gaining importance as the limitations of primary indoor interventions are reached. Strategies to target ovipositing females or her offspring are broadly applicable because all mosquitoes require aquatic habitats for immature development irrespective of their biting or resting preferences. Oviposition site selection by gravid females is frequently studied by counting early instar larvae in habitats; an approach which is valid only if the number of larvae correlates with the number of females laying eggs. This hypothesis was tested against the alternative, that a higher abundance of larvae results from improved survival of a similar or fewer number of families. Methods In a controlled experiment, 20 outdoor artificial ponds were left uncovered for 4 days to allow oviposition by wild mosquitoes, then covered with netting and first and second instar larvae sampled daily. Natural Anopheles habitats of two different types were also identified, and all visible larvae sampled. All larvae were identified to species, and most samples of the predominant species, Anopheles arabiensis, were genotyped using microsatellites for sibling group reconstructions using two contrasting softwares, BAPS and COLONY. Results In the ponds, the number of families reconstructed by each software significantly predicted larval abundance (BAPS R2 = 0.318, p = 0.01; COLONY R2 = 0.476, p = 0.001), and suggested that around 50% of females spread larvae across multiple ponds (skip oviposition). From natural habitats, the mean family size again predicted larval abundance using BAPS (R2 = 0.829, p = 0.017) though not using COLONY (R2 = 0.218, p = 0.68), but both softwares once more suggested high rates of skip oviposition (in excess of 50%). Conclusion This study shows that, whether in closely-located artificial habitats or natural breeding sites, higher early instar larval densities result from more females laying eggs in these sites. These results provide empirical support for use of early instar larval abundance as an index for oviposition site preference. Furthermore, the sharing of habitats by multiple females and the high skip-oviposition rate in An. arabiensis suggest that larviciding by auto-dissemination of insecticide may be successful.
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Affiliation(s)
- Joel O Odero
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi, Kenya. .,Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK.
| | - Ulrike Fillinger
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Emily J Rippon
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Daniel K Masiga
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - David Weetman
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
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Monroe A, Mihayo K, Okumu F, Finda M, Moore S, Koenker H, Lynch M, Haji K, Abbas F, Ali A, Greer G, Harvey S. Human behaviour and residual malaria transmission in Zanzibar: findings from in-depth interviews and direct observation of community events. Malar J 2019; 18:220. [PMID: 31262306 PMCID: PMC6604484 DOI: 10.1186/s12936-019-2855-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/25/2019] [Indexed: 11/24/2022] Open
Abstract
Background Zanzibar has maintained malaria prevalence below 1% for the past decade, yet elimination remains elusive despite high coverage of core vector control interventions. As part of a study investigating the magnitude and drivers of residual transmission in Zanzibar, qualitative methods were utilized to better understand night time activities and sleeping patterns, individual and community-level risk perceptions, and malaria prevention practices. Methods A total of 62 in-depth interviews were conducted with community members and local leaders across six sites on Unguja Island, Zanzibar. Twenty semi-structured community observations of night-time activities and special events were conducted to complement interview findings. Data were transcribed verbatim, coded, and analysed using a thematic approach. Results Participants reported high levels of ITN use, but noted gaps in protection, particularly when outdoors or away from home. Routine household and community activities were common in evenings before bed and early mornings, while livelihood activities and special events lasted all or most of the night. Gender variation was reported, with men routinely spending more time away from home than women and children. Outdoor sleeping was reported during special events, such as weddings, funerals, and religious ceremonies. Participants described having difficulty preventing mosquito bites while outdoors, travelling, or away from home, and perceived higher risk of malaria infection during these times. Travel and migration emerged as a crucial issue and participants viewed seasonal workers coming from mainland Tanzania as more likely to have a malaria infection and less likely to be connected to prevention and treatment services in Zanzibar. Some community leaders reported taking the initiative to register seasonal workers coming into their community and linking them to testing and treatment services. Conclusions Targeting malaria interventions effectively is critical and should be informed by a clear understanding of relevant human behaviour. These findings highlight malaria prevention gaps in Zanzibar, and the importance of identifying new approaches to complement current interventions and accelerate the final phases of malaria elimination. Development and deployment of complementary interventions should consider human behaviour, including gender norms, that can influence exposure to malaria vectors and prevention practices. Expansion of community-level programmes targeting travellers and seasonal workers should also be explored.
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Affiliation(s)
- April Monroe
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA. .,University of Basel, Basel, Switzerland. .,Swiss Tropical and Public Health Institute, Basel, Switzerland.
| | - Kimberly Mihayo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Fredros Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Republic of South Africa.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Marceline Finda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Sarah Moore
- University of Basel, Basel, Switzerland.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Hannah Koenker
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
| | - Matthew Lynch
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
| | - Khamis Haji
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - Faiza Abbas
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - Abdullah Ali
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - George Greer
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar Es Salaam, Tanzania
| | - Steven Harvey
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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Finda MF, Moshi IR, Monroe A, Limwagu AJ, Nyoni AP, Swai JK, Ngowo HS, Minja EG, Toe LP, Kaindoa EW, Coetzee M, Manderson L, Okumu FO. Linking human behaviours and malaria vector biting risk in south-eastern Tanzania. PLoS One 2019; 14:e0217414. [PMID: 31158255 PMCID: PMC6546273 DOI: 10.1371/journal.pone.0217414] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 05/10/2019] [Indexed: 12/24/2022] Open
Abstract
To accelerate malaria elimination in areas where core interventions such as insecticide-treated nets (ITNs) are already widely used, it is crucial to consider additional factors associated with persistent transmission. Qualitative data on human behaviours and perceptions regarding malaria risk was triangulated with quantitative data on Anopheles mosquito bites occurring indoors and outdoors in south-eastern Tanzania communities where ITNS are already used but lower level malaria transmission persists. Each night (18:00h-07:00h), trained residents recorded human activities indoors, in peri-domestic outdoor areas, and in communal gatherings. Host-seeking mosquitoes were repeatedly collected indoors and outdoors hourly, using miniaturized exposure-free double net traps (DN-Mini) occupied by volunteers. In-depth interviews were conducted with household representatives to explore perceptions on persistent malaria and its control. Higher proportions of people stayed outdoors than indoors in early-evening and early-morning hours, resulting in higher exposures outdoors than indoors during these times. However, exposure during late-night hours (22:00h–05:00h) occurred mostly indoors. Some of the popular activities that kept people outdoors included cooking, eating, relaxing and playing. All households had at least one bed net, and 83.9% of people had access to ITNs. Average ITN use was 96.3%, preventing most indoor exposure. Participants recorgnized the importance of ITNs but also noted that the nets were not perfect. No complementary interventions were reported being used widely. Most people believed transmission happens after midnight. We conclude that insecticide-treated nets, where properly used, can still prevent most indoor exposures, but significant risk continues unabated before bedtime, outdoors and at communal gatherings. Such exposure is greatest for rural and low-income households. There is therefore an urgent need for complementary interventions, particularly those targeting outdoor-biting and are applicable for all people including the marginalised populations such as migratory farmers and fishermen. Besides, the differences in community understanding of ongoing transmission, and feedback on imperfections of ITNs should be considered when updating malaria-related communication and interventions.
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Affiliation(s)
- Marceline F. Finda
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, South Africa
- * E-mail:
| | - Irene R. Moshi
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, South Africa
| | - April Monroe
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
- Johns Hopkins Center for Communication Programs, Baltimore, MD, United States of America
- University of Basel, Basel, Switzerland
- Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland
| | - Alex J. Limwagu
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Anna P. Nyoni
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Johnson K. Swai
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Halfan S. Ngowo
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Elihaika G. Minja
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Lea P. Toe
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Emmanuel W. Kaindoa
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, South Africa
| | - Maureen Coetzee
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Braamofontein, South Africa
| | - Lenore Manderson
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, South Africa
| | - Fredros O. Okumu
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, South Africa
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow
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Getachew D, Gebre-Michael T, Balkew M, Tekie H. Species composition, blood meal hosts and Plasmodium infection rates of Anopheles mosquitoes in Ghibe River Basin, southwestern Ethiopia. Parasit Vectors 2019; 12:257. [PMID: 31122286 PMCID: PMC6533711 DOI: 10.1186/s13071-019-3499-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 05/09/2019] [Indexed: 01/25/2023] Open
Abstract
Background Vector control interventions using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are commonly practiced tools for the control of malaria in Ethiopia. In order to evaluate the effectiveness of these control interventions, and understand the prevailing malaria vectors, their incrimination in disease transmission, and their resting and feeding behavior, we set out to identify the Anopheles species, their blood meal sources, and entomological inoculation rate (EIR) in Ghibe and Darge within the Ghibe River basin, southwestern Ethiopia. Methods Adult Anopheles mosquitoes were sampled both indoors and outdoors from January 2015 to October 2016 using Centers for Disease Control and Prevention (CDC) light traps, pyrethrum spray catch (PSC), artificial pit shelters and mouth aspirators. Mosquito species were morphologically identified, and their blood meal sources and malaria sporozoite rates were assessed using enzyme-linked immunosorbent assays. Results In total, 13 species of Anopheles mosquitoes were identified, among which Anopheles gambiae (s.l.) was the predominant species: 87.9 and 67.7% in Ghibe and Darge, respectively. The mean density of An. gambiae (s.l.) collected per night using CDC light traps was 1.8 and 0.7 outdoors and indoors, respectively, in Ghibe, and 0.125 and 0.07 indoors and outdoors, respectively, in Darge. Anopheles mosquito abundance was higher in houses near the river than in houses far from the river in both study sites. Among Anopheles mosquitoes sampled using CDC light trap catches, 67.6% were unfed and the indoor and outdoor human blood indices of An. gambiae (s.l.) were 58.4 and 15.8%, respectively in Ghibe, while in Darge, they were 57.1 and 50%, respectively. Sporozoite rates were 0.07% for P. vivax and 0.07% for P. falciparum in Ghibe and zero in Darge. In Ghibe, the overall EIRs for P. falciparum and P. vivax were zero and 8.4 infective bites/person/year, respectively, in 2015, while zero and 5.4 infective bites/person/year for P. vivax and P. falciparum, respectively, in 2016. No Plasmodium-positive Anopheles mosquitoes were identified from Darge. Conclusions Anopheles gambiae (s.l.), the principal vector of malaria in Ethiopia was the most abundant species both indoors and outdoors, fed both on human and cattle blood and occurred at higher frequencies near rivers. Anopheles gambiae (s.l.) that were circumsporozoite-positive for Plasmodium species were collected from Ghibe, but not Darge.
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Affiliation(s)
- Dejene Getachew
- Department of Biology, Dire Dawa University, P. O. Box 1362, Dire Dawa, Ethiopia. .,Department of Zoological Sciences, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia.
| | - Teshome Gebre-Michael
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
| | - Meshesha Balkew
- Abt Associates, PMI VectorLink Ethiopia Project, Addis Ababa, Ethiopia
| | - Habte Tekie
- Department of Zoological Sciences, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
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Kwan MWC, Bosak A, Kline J, Pita MA, Giel N, Pereira RM, Koehler PG, Kline DL, Batich CD, Willenberg BJ. A Low-Cost, Passive Release Device for the Surveillance and Control of Mosquitoes. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16091488. [PMID: 31035536 PMCID: PMC6539509 DOI: 10.3390/ijerph16091488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 04/24/2019] [Accepted: 04/26/2019] [Indexed: 12/02/2022]
Abstract
Mosquitoes continue to be a major threat to global health, and the ability to reliably monitor, catch, and kill mosquitoes via passive traps is of great importance. Global, low-cost, and easy-to-use outdoor devices are needed to augment existing efforts in mosquito control that combat the spread of disease, such as Zika. Thus, we have developed a modular, portable, non-powered (passive), self-contained, and field-deployable device suitable for releasing volatiles with a wide range of applications such as attracting, repelling, and killing mosquitoes. This unique device relies on a novel nested wick and two-reservoir design that achieves a constant release of volatiles over several hundred hours. Devices loaded with one of either two compounds, geraniol or 1-methylpiperazine (MP), were tested in a controlled environment (32 °C and 70% relative humidity), and both compounds achieved a constant release from our devices at a rate of 2.4 mg/h and 47 mg/h, respectively. The liquid payload can be volatile attractants or repellants as well as mosquitocide-containing feeding solutions for capture and surveillance. This low-cost device can be utilized for both civilian and military mosquito control purposes, but it will be particularly important for protecting those in economically repressed environments, such as sub-Saharan Africa and Central and South America.
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Affiliation(s)
- Michael W C Kwan
- Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL 32827, USA.
| | - Alexander Bosak
- Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL 32827, USA.
| | - Jedidiah Kline
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611, USA.
| | - Mario A Pita
- United States Department of Agriculture-Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32608, USA.
| | - Nicholas Giel
- Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL 32827, USA.
| | - Roberto M Pereira
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32611-0620, USA.
| | - Philip G Koehler
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32611-0620, USA.
| | - Daniel L Kline
- United States Department of Agriculture-Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32608, USA.
| | - Christopher D Batich
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611, USA.
- J. Crayton Pruitt Family Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA.
| | - Bradley Jay Willenberg
- Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL 32827, USA.
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Foy BD, Alout H, Seaman JA, Rao S, Magalhaes T, Wade M, Parikh S, Soma DD, Sagna AB, Fournet F, Slater HC, Bougma R, Drabo F, Diabaté A, Coulidiaty AGV, Rouamba N, Dabiré RK. Efficacy and risk of harms of repeat ivermectin mass drug administrations for control of malaria (RIMDAMAL): a cluster-randomised trial. Lancet 2019; 393:1517-1526. [PMID: 30878222 PMCID: PMC6459982 DOI: 10.1016/s0140-6736(18)32321-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 09/11/2018] [Accepted: 09/13/2018] [Indexed: 10/27/2022]
Abstract
BACKGROUND Ivermectin is widely used in mass drug administrations for controlling neglected parasitic diseases, and can be lethal to malaria vectors that bite treated humans. Therefore, it could be a new tool to reduce plasmodium transmission. We tested the hypothesis that frequently repeated mass administrations of ivermectin to village residents would reduce clinical malaria episodes in children and would be well tolerated with minimal harms. METHODS We invited villages (clusters) in Burkina Faso to participate in a single-blind (outcomes assessor), parallel-assignment, two-arm, cluster-randomised trial over the 2015 rainy season. Villages were assigned (1:1) by random draw to either the intervention group or the control group. In both groups, all eligible participants who consented to the treatment and were at least 90 cm in height received single oral doses of ivermectin (150-200 μg/kg) and albendazole (400 mg), and those in the intervention group received five further doses of ivermectin alone at 3-week intervals thereafter over the 18-week treatment phase. The primary outcome was cumulative incidence of uncomplicated malaria episodes over 18 weeks (analysed on a cluster intention-to-treat basis) in an active case detection cohort of children aged 5 years or younger living in the study villages. This trial is registered with ClinicalTrials.gov, number NCT02509481. FINDINGS Eight villages agreed to participate, and four were randomly assigned to each group. 2712 participants (1333 [49%] males and 1379 [51%] females; median age 15 years [IQR 6-34]), including 590 children aged 5 years or younger, provided consent and were enrolled between May 22 and July 20, 2015 (except for 77 participants enrolled after these dates because of unavailability before the first mass drug administration, travel into the village during the trial, or birth), with 1447 enrolled into the intervention group and 1265 into the control group. 330 (23%) participants in the intervention group and 233 (18%) in the control group met the exclusion criteria for mass drug administration. Most children in the active case detection cohort were not treated because of height restrictions. 14 (4%) children in the intervention group and 10 (4%) in the control group were lost to follow-up. Cumulative malaria incidence was reduced in the intervention group (648 episodes among 327 children; estimated mean 2·00 episodes per child) compared with the control group (647 episodes among 263 children; 2·49 episodes per child; risk difference -0·49 [95% CI -0·79 to -0·21], p=0·0009, adjusted for sex and clustering). The risk of adverse events among all participants did not differ between groups (45 events [3%] among 1447 participants in the intervention group vs 24 events [2%] among 1265 in the control group; risk ratio 1·63 [1·01 to 2·67]; risk difference 1·21 [0·04 to 2·38], p=0·060), and no adverse reactions were reported. INTERPRETATION Frequently repeated mass administrations of ivermectin during the malaria transmission season can reduce malaria episodes among children without significantly increasing harms in the populace. FUNDING Bill & Melinda Gates Foundation.
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Affiliation(s)
- Brian D Foy
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA.
| | - Haoues Alout
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Jonathan A Seaman
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Sangeeta Rao
- Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Tereza Magalhaes
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Martina Wade
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Sunil Parikh
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Dieudonné D Soma
- Institute of Research in Health Sciences, Western Regional Direction, National Center for Scientific and Technological Research, Bobo-Dioulasso, Burkina Faso; International Mixed Laboratory on Vector Diseases, Bobo-Dioulasso, Burkina Faso
| | - André B Sagna
- International Mixed Laboratory on Vector Diseases, Bobo-Dioulasso, Burkina Faso; Research Institute for Development, Infectious Diseases, and Vectors: Ecology, Genetics, Evolution and Control, National Centre for Scientific Research, University of Montpellier, Montpellier, France
| | - Florence Fournet
- International Mixed Laboratory on Vector Diseases, Bobo-Dioulasso, Burkina Faso; Research Institute for Development, Infectious Diseases, and Vectors: Ecology, Genetics, Evolution and Control, National Centre for Scientific Research, University of Montpellier, Montpellier, France
| | - Hannah C Slater
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Roland Bougma
- National Program for the Fight against Neglected Tropical Diseases, Department of Disease Control, Ministry of Health, Ouagadougou, Burkina Faso
| | - François Drabo
- National Program for the Fight against Neglected Tropical Diseases, Department of Disease Control, Ministry of Health, Ouagadougou, Burkina Faso
| | - Abdoulaye Diabaté
- Institute of Research in Health Sciences, Western Regional Direction, National Center for Scientific and Technological Research, Bobo-Dioulasso, Burkina Faso; International Mixed Laboratory on Vector Diseases, Bobo-Dioulasso, Burkina Faso
| | | | - Nöel Rouamba
- Institute of Research in Health Sciences, Western Regional Direction, National Center for Scientific and Technological Research, Bobo-Dioulasso, Burkina Faso
| | - Roch K Dabiré
- Institute of Research in Health Sciences, Western Regional Direction, National Center for Scientific and Technological Research, Bobo-Dioulasso, Burkina Faso; International Mixed Laboratory on Vector Diseases, Bobo-Dioulasso, Burkina Faso
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Finda MF, Kaindoa EW, Nyoni AP, Okumu FO. 'The mosquitoes are preparing to attack us': knowledge and perceptions of communities in south-eastern Tanzania regarding mosquito swarms. Malar J 2019; 18:56. [PMID: 30808344 PMCID: PMC6390612 DOI: 10.1186/s12936-019-2686-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 02/21/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Targeting swarms of male Anopheles mosquitoes with techniques such as aerosol spraying could potentially suppress malaria vector populations and parasite transmission. Unfortunately, research on Anopheles swarming behaviours is limited, particularly in East Africa where only a handful of studies have been done. New evidence has recently emerged that such swarms are common even in Tanzania, where they could be readily identified and characterized by community-based volunteers, and potentially targeted for control. However, improved understanding of public knowledge and perceptions will be crucial for successful uptake of any interventions targeting swarms. METHODS Explanatory sequential mixed methods approach was used to assess knowledge and perceptions regarding mosquito swarms among community members in Ulanga and Kilombero districts, south-eastern Tanzania. A survey questionnaire was administered to 307 respondents, after which focus group discussions were conducted to clarify responses regarding mosquito swarms and malaria transmission. Findings from both study components were used to draw qualitative inferences. RESULTS Most community members (83%) had previously seen mosquito swarms, predominantly in farms, over long grasses or bushes, above ponds and over roofs of houses and pit-latrines. However, there was little evidence that community members could distinguish between mosquito swarms and those of other insects. Neither were they aware that swarms consisted mostly of male mosquitoes. Swarming was associated with mosquitoes preparing to attack people, foraging for food, playing or resting. Very few respondents associated swarming with mosquito mating. Nearly all community members were willing to accept interventions targeting mosquito swarms; and approximately three quarters would pay for such interventions, between 0.9 and 2.3 USD/year. CONCLUSION Majority of the community members recognized presence of mosquito swarms in their communities but did not associate these swarms with mosquito mating. Instead, swarming was associated with mosquitoes seeking food or planning to attack people, and thus were generally considered dangerous. This understanding created the basis for wide-acceptance of interventions targeting swarming mosquitoes. Although the likelihood of actual interventions targeting swarms is still low, such community knowledge will be crucial in future field studies of mosquito swarms and possible inclusion of community members in mosquito control efforts.
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Affiliation(s)
- Marceline F Finda
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Anna P Nyoni
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Fredros O Okumu
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
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50
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Measuring and characterizing night time human behaviour as it relates to residual malaria transmission in sub-Saharan Africa: a review of the published literature. Malar J 2019; 18:6. [PMID: 30634963 PMCID: PMC6329148 DOI: 10.1186/s12936-019-2638-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/08/2019] [Indexed: 11/29/2022] Open
Abstract
Background Malaria cases and deaths decreased dramatically in recent years, largely due to effective vector control interventions. Persistence of transmission after good coverage has been achieved with high-quality vector control interventions, namely insecticide-treated nets or indoor residual spraying, poses a significant challenge to malaria elimination efforts. To understand when and where remaining transmission is occurring, it is necessary to look at vector and human behaviour, and where they overlap. To date, a review of human behaviour related to residual malaria transmission has not been conducted. Methods Studies were identified through PubMed and Google Scholar. Hand searches were conducted for all references cited in articles identified through the initial search. The review was limited to English language articles published between 2000 and 2017. Publications with primary data from a malaria endemic setting in sub-Saharan Africa and a description of night time human behaviours were included. Results Twenty-six publications were identified that met inclusion criteria. Study results fit into two broad categories: when and where people are exposed to malaria vectors and what people are doing at night that may increase their contact with malaria vectors. Among studies that quantified human-vector interaction, a majority of exposure occurred indoors during sleeping hours for unprotected individuals, with some variation across time, contexts, and vector species. Common night time activities across settings included household chores and entertainment during evening hours, as well as livelihood and large-scale socio-cultural events that can last throughout the night. Shifting sleeping patterns associated with travel, visitors, illness, farming practices, and outdoor sleeping, which can impact exposure and use of prevention measures, were described in some locations. Conclusions While the importance of understanding human-vector interaction is well-established, relatively few studies have included human behaviour when measuring exposure to malaria vectors. Broader application of a standardized approach to measuring human-vector interaction could provide critical information on exposure across settings and over time. In-depth understanding of night time activities that occur during times when malaria vectors are active and barriers to prevention practices in different contexts should also be considered. This information is essential for targeting existing interventions and development and deployment of appropriate complementary prevention tools.
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