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Liu M, Zhang Y, Li Q, Zhou X, Yan T, Li J, Zhang H, Wang L, Wang G, Li R, Tong Y, Zeng X. Spatial distribution and environmental correlations of Culex pipiens pallens (Diptera: Culicidae) in Haidian district, Beijing. JOURNAL OF MEDICAL ENTOMOLOGY 2024; 61:948-958. [PMID: 38747350 PMCID: PMC11239791 DOI: 10.1093/jme/tjae063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 04/18/2024] [Accepted: 04/29/2024] [Indexed: 07/13/2024]
Abstract
Culex pipiens pallens Coquillett, 1898 (Diptera: Culicidae) was the dominant health threat to mosquito species in Beijing, and it is important to unravel the spatial distribution and environmental correlations of Cx. pipiens pallens in Beijing. 3S technology methods and spatial statistics were used to clarify the distribution pattern. Subsequently, linear and spatial regression were performed to detect the environmental factors linked with the density of Cx. pipiens pallens. The same "middle peak" spatial distribution pattern was observed for Cx. pipiens pallens density at the community, subdistrict, and loop area levels in our study area. In addition, there were various correlated environmental factors at the community and subdistrict scales. At the community scale, the summary values of the Modified Normalized Difference Water Index (MNDWI) in 2 km buffer zone (MNDWI_2K) were negatively correlated, and the summary values of Normalized Difference Built-up Index (NDBI) in 800 m buffer zone (NDBI_800) was positively correlated to the Cx. pipiens pallens density. However, the summary values of Normalized Difference Vegetation Index and Nighttime Light Index significantly affected Cx. pipiens pallens density at the subdistrict scale. Our findings provide insight into the spatial distribution pattern of Cx. pipiens pallens density and its associated environmental risk factors at different spatial scales in the Haidian district of Beijing for the first time. The results could be used to predict the Cx. pipiens pallens density as well as the risk of lymphatic filariasis (LF) infection, which would help implement prevention and control measures to prevent future risks of biting and LF transmission in Beijing.
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Affiliation(s)
- Meide Liu
- Institute for Disinfection and Vector Control, Beijing Municipal Center for Disease Prevention and Control, 16 Hepingli Zhong Street, Dongcheng District, Beijing 100013, China
| | - Yong Zhang
- Institute for Disinfection and Vector Control, Beijing Municipal Center for Disease Prevention and Control, 16 Hepingli Zhong Street, Dongcheng District, Beijing 100013, China
| | - Qiuhong Li
- Institute for Disinfection and Vector Control, Beijing Municipal Center for Disease Prevention and Control, 16 Hepingli Zhong Street, Dongcheng District, Beijing 100013, China
| | - Xiaojie Zhou
- Institute for Disinfection and Vector Control, Beijing Municipal Center for Disease Prevention and Control, 16 Hepingli Zhong Street, Dongcheng District, Beijing 100013, China
| | - Ting Yan
- Institute for Disinfection and Vector Control, Beijing Municipal Center for Disease Prevention and Control, 16 Hepingli Zhong Street, Dongcheng District, Beijing 100013, China
| | - Jing Li
- Institute for Disinfection and Vector Control, Beijing Municipal Center for Disease Prevention and Control, 16 Hepingli Zhong Street, Dongcheng District, Beijing 100013, China
| | - Hongjiang Zhang
- Institute for Disinfection and Vector Control, Beijing Municipal Center for Disease Prevention and Control, 16 Hepingli Zhong Street, Dongcheng District, Beijing 100013, China
| | - Lei Wang
- Department of Disinfection and Sanitation, Haidian District Center for Disease Control and Prevention, Beijing 100037, China
| | - Guangwen Wang
- Department of Disinfection and Vector Control, Fangshan District Center for Disease Control and Prevention, Beijing 102446, China
| | - Ruoxi Li
- Department of Disinfection and Vector Control, Fengtai District Center for Disease Control and Prevention, Beijing 100068, China
| | - Ying Tong
- Institute for Disinfection and Vector Control, Beijing Municipal Center for Disease Prevention and Control, 16 Hepingli Zhong Street, Dongcheng District, Beijing 100013, China
| | - Xiaopeng Zeng
- Institute for Disinfection and Vector Control, Beijing Municipal Center for Disease Prevention and Control, 16 Hepingli Zhong Street, Dongcheng District, Beijing 100013, China
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Liu MD, Zhang HD, Huang Y, Cheng JX, Li CX, Zhao TY. Spatial distribution of Japanese encephalitis cases and correlated geo-environmental factors in southern and northern counties of China. Acta Trop 2024; 255:107246. [PMID: 38729328 DOI: 10.1016/j.actatropica.2024.107246] [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: 03/28/2024] [Revised: 05/07/2024] [Accepted: 05/07/2024] [Indexed: 05/12/2024]
Abstract
Japanese encephalitis (JE) is a mosquito-borne disease with a spatial distribution that is linked to geo-environmental factors. The spatial distribution of JE cases and correlated geo-environmental factors were investigated in two critical counties in southern and northern China. Based on maps, enhanced thematic mapper (ETM) remote sensing datasets from Landsat and spatial datasets of JE cases, spatial distribution and spatial cluster analyses of JE cases at the village scale were performed by using the standard deviational ellipse and Ripleys K-function. Global and regional spatial cluster analyses of JE cases were also performed by using Moran's index. Regression analysis was used to analyze the relationships between geo-environmental characteristics and the risk of JE cases. At the study sites, the JE cases were not spatially clustered at the village or district (global) level, whereas there was a spatial cluster at the district (local) level. Diversity-related features for JE patients at the district and village levels were detected at two sites. In the southern counties, the distance of a village from a road was related to the village-level JE risk (OR: 0.530, 95 CI: 0.297-0.947, P = 0.032), and the number of township-level JE cases was linked to the distance of the district center from the road (R =-0.467, P = 0.025) and road length (R = 0.516, P = 0.012) in the administrative area. In northern China, the modified normalized difference water index (MNDWI) in the 5 km buffer around the village was related to village-level JE risk (OR: 0.702, 95% CI: 0.524-0.940, P = 0.018), and the number of township-level JE cases was related to the MNDWI in the administrative region (R =-0.522, P = 0.038). This study elucidates the spatial distribution patterns of JE cases and risk, as well as correlated geo-environmental features, at various spatial scales. This study will significantly assist the JE control efforts of the local Centers for Disease Control and Prevention (CDC), which is the base-level CDC, particularly concerning the allocation of medicine and medical staff, the development of immunological plans, and the allocation of pesticides and other control measures for the mosquito vectors of JE.
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Affiliation(s)
- Mei-De Liu
- State Key Laboratory of Pathogens and Biosecurity, Beijing 100071, China
| | - Heng-Duan Zhang
- State Key Laboratory of Pathogens and Biosecurity, Beijing 100071, China
| | - Yi Huang
- Hunan Center for Disease Control and Prevention, Changsha 410005, China
| | - Jing-Xia Cheng
- Shanxi Center for Disease Control and Prevention, Taiyuan 030012, China
| | - Chun-Xiao Li
- State Key Laboratory of Pathogens and Biosecurity, Beijing 100071, China
| | - Tong-Yan Zhao
- State Key Laboratory of Pathogens and Biosecurity, Beijing 100071, China.
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Savi MK, Pandey B, Swain A, Lim J, Callo-Concha D, Azondekon GR, Wahjib M, Borgemeister C. Urbanization and malaria have a contextual relationship in endemic areas: A temporal and spatial study in Ghana. PLOS GLOBAL PUBLIC HEALTH 2024; 4:e0002871. [PMID: 38814949 PMCID: PMC11139300 DOI: 10.1371/journal.pgph.0002871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 04/30/2024] [Indexed: 06/01/2024]
Abstract
In West Africa, malaria is one of the leading causes of disease-induced deaths. Existing studies indicate that as urbanization increases, there is corresponding decrease in malaria prevalence. However, in malaria-endemic areas, the prevalence in some rural areas is sometimes lower than in some peri-urban and urban areas. Therefore, the relationship between the degree of urbanization, the impact of living in urban areas, and the prevalence of malaria remains unclear. This study explores this association in Ghana, using epidemiological data at the district level (2015-2018) and data on health, hygiene, and education. We applied a multilevel model and time series decomposition to understand the epidemiological pattern of malaria in Ghana. Then we classified the districts of Ghana into rural, peri-urban, and urban areas using administratively defined urbanization, total built areas, and built intensity. We converted the prevalence time series into cross-sectional data for each district by extracting features from the data. To predict the determinant most impacting according to the degree of urbanization, we used a cluster-specific random forest. We find that prevalence is impacted by seasonality, but the trend of the seasonal signature is not noticeable in urban and peri-urban areas. While urban districts have a slightly lower prevalence, there are still pockets with higher rates within these regions. These areas of high prevalence are linked to proximity to water bodies and waterways, but the rise in these same variables is not associated with the increase of prevalence in peri-urban areas. The increase in nightlight reflectance in rural areas is associated with an increased prevalence. We conclude that urbanization is not the main factor driving the decline in malaria. However, the data indicate that understanding and managing malaria prevalence in urbanization will necessitate a focus on these contextual factors. Finally, we design an interactive tool, 'malDecision' that allows data-supported decision-making.
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Affiliation(s)
- Merveille Koissi Savi
- Center for Development Research (ZEF), University of Bonn, North Rhine-Westphalia, Germany
- Department of Medical Oncology, Dana Farber Cancer Institute, Harvard School of Medicine, Boston, Massachusetts, United States of America
| | - Bhartendu Pandey
- Department of Civil & Environmental Engineering, Princeton University, Princeton, New Jersey, United States of America
- Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
| | - Anshuman Swain
- Department of Biology, University of Maryland, College Park, Maryland, United States of America
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Jeongki Lim
- Parsons School of Design, The New School, New York, New York, United States of America
| | - Daniel Callo-Concha
- Center for Development Research (ZEF), University of Bonn, North Rhine-Westphalia, Germany
- University of Koblenz-Landau, Institute for Environmental Sciences, North Rhine-Westphalia, German
| | | | - Mohammed Wahjib
- National Malaria Control Programme, Ministry of Health, Accra, Ghana
| | - Christian Borgemeister
- Center for Development Research (ZEF), University of Bonn, North Rhine-Westphalia, Germany
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Kampango A, Saleh F, Furu P, Konradsen F, Alifrangis M, Schiøler KL, Weldon CW. A protocol for evaluating the entomological impact of larval source reduction on mosquito vectors at hotel compounds in Zanzibar. PLoS One 2023; 18:e0294773. [PMID: 38011153 PMCID: PMC10681246 DOI: 10.1371/journal.pone.0294773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 11/08/2023] [Indexed: 11/29/2023] Open
Abstract
There is an increasing awareness of the association between tourism activity and risks of emerging mosquito-borne diseases (MBDs) worldwide. In previous studies we showed that hotels in Zanzibar may play an important role in maintaining residual foci of mosquito vectors populations of public health concern. These findings indicated larval sources removal (LSR) interventions may have a significant negative impact on vector communities. However, a thorough analysis of the response vector species to potential LSM strategies must be evaluated prior to implementation of a large-scale area-wide control campaign. Here we propose a protocol for evaluation of the impact of LSR against mosquito vectors at hotel settings in Zanzibar. This protocol is set to determine the efficacy of LSR in a randomized control partial cross-over experimental design with four hotel compounds representing the unit of randomization for allocation of interventions. However, the protocol can be applied to evaluate the impact of LRS in more than four sites. Proposed interventions are active removal of disposed containers, and installation of water dispenser to replace single use discarded plastic water bottles, which were identified as the most important source of mosquitoes studied hotels. The ideal time for allocating intervention to the intervention arms the dry season, when the mosquito abundance is predictably lower. The possible impact of interventions on mosquito occurrence and abundance risks is then evaluated throughout subsequent rainy and dry seasons. If an appreciable reduction in mosquito abundance and occurrence risks is observed during the trial period, intervention could be extended to the control arm to determine whether any potential reduction of mosquito density is reproducible. A rigorous evaluation of the proposed LRS interventions will inspire large scale trials and provide support for evidence-based mosquito management at hotel facilities in Zanzibar and similar settings.
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Affiliation(s)
- Ayubo Kampango
- Sector de Estudos de Vectores, Instituto Nacional de Saúde (INS), Vila de Marracuene, Província de Maputo, Mozambique
- Department of Zoology and Entomology, University of Pretoria (UP), Pretoria, South Africa
| | - Fatma Saleh
- Department of Allied Health Sciences, School of Health and Medical Sciences, The State University of Zanzibar, Zanzibar, Tanzania
| | - Peter Furu
- Global Health Section, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Flemming Konradsen
- Global Health Section, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Michael Alifrangis
- Center for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Karin L. Schiøler
- Global Health Section, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Christopher W. Weldon
- Department of Zoology and Entomology, University of Pretoria (UP), Pretoria, South Africa
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Biruksew A, Demeke A, Birhanu Z, Golassa L, Getnet M, Yewhalaw D. Schoolchildren with asymptomatic malaria are potential hotspot for malaria reservoir in Ethiopia: implications for malaria control and elimination efforts. Malar J 2023; 22:311. [PMID: 37845680 PMCID: PMC10580533 DOI: 10.1186/s12936-023-04736-7] [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: 07/14/2023] [Accepted: 09/30/2023] [Indexed: 10/18/2023] Open
Abstract
BACKGROUND Schoolchildren with asymptomatic malaria infections often go undiagnosed and untreated, serving as reservoirs for infection that hamper malaria control and elimination efforts. In this context, little is known about the magnitude of asymptomatic malaria infections in apparently healthy schoolchildren in Ethiopia. This study was aimed at determining the prevalence of asymptomatic malaria infection and its associated factors in apparently healthy schoolchildren in Ethiopia. METHODS From September 2021 to January 2022, a school-based cross-sectional study was conducted on 994 apparently healthy schoolchildren (aged 6-15 years) selected from 21 primary schools in the Gomma district, of Jimma zone, southwestern Oromia, Ethiopia. A multi-stage sampling technique was used to select schools and participants. After allocating the total sample proportionally to each school and then to each grade, participants were selected using the lottery method from a list of student records (rosters). Finger-pricked blood samples were collected for microscopy blood film preparation and malaria rapid diagnostic test (RDT) (SD Bioline Malaria Ag Pf/Pv). Moreover, dry blood spots (DBSs) were prepared onto filter papers for quantitative real time polymerase chain reaction (qPCR) analysis. RESULTS As determined by RDT and microscopy, the prevalence of asymptomatic malaria was 2.20% and 1.51%, respectively. Using qPCR, the overall prevalence was 5.03% (50/994). Of this, Plasmodium falciparum, Plasmodium vivax and mixed infections accounted for 90%, 6% and 4%, respectively. Submicroscopic asymptomatic malaria infection was also accounted for 70% (35/50) of the overall prevalence. Household head age, nighttime outdoor activities of household heads, family history of malaria, absence of insecticide-treated nets (ITN), and presence of stagnant water around the houses are all significantly associated with asymptomatic malaria infections among schoolchildren. CONCLUSIONS This study found that both RDT and microscopy underestimated the prevalence of asymptomatic malaria in schoolchildren. However, qPCR was able to detect even low levels of parasitaemia and revealed a higher prevalence of asymptomatic submicroscopic malaria infections. The findings imply that schoolchildren with asymptomatic malaria infection are potential hotspot for malaria reservoir that fuels ongoing transmission. Therefore, it is imperative to include schoolchildren and schools in malaria intervention package and equally important is the adoption of more advanced and sensitive diagnostic tools, which would be crucial for successful malaria control and elimination efforts. Targeted interventions for asymptomatic malaria-infected schoolchildren can provide invaluable support to the National Malaria Control Programme in controlling and eventually eliminating the disease.
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Affiliation(s)
- Abdissa Biruksew
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIRC), Jimma University, Jimma, Ethiopia
| | | | - Zewdie Birhanu
- Department of Health, Behavior, and Society, Faculty of Public Health, Institute of Health Jimma University, Jimma, Ethiopia
| | - Lemu Golassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Masrie Getnet
- Department of Biostatistics and Epidemiology, Faculty of Public Health, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIRC), Jimma University, Jimma, Ethiopia
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Tong Y, Jiang H, Xu N, Wang Z, Xiong Y, Yin J, Huang J, Chen Y, Jiang Q, Zhou Y. Global Distribution of Culex tritaeniorhynchus and Impact Factors. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:4701. [PMID: 36981610 PMCID: PMC10048298 DOI: 10.3390/ijerph20064701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/04/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
Culex tritaeniorhynchus is the primary vector of Japanese encephalitis (JE) and has a wide global distribution. However, the current and future geographic distribution maps of Cx. tritaeniorhynchus in global are still incomplete. Our study aims to predict the potential distribution of Cx. tritaeniorhynchus in current and future conditions to provide a guideline for the formation and implementation of vector control strategies all over the world. We collected and screened the information on the occurrence of Cx. tritaeniorhynchus by searching the literature and online databases and used ten algorithms to investigate its global distribution and impact factors. Cx. tritaeniorhynchus had been detected in 41 countries from 5 continents. The final ensemble model (TSS = 0.864 and AUC = 0.982) indicated that human footprint was the most important factor for the occurrence of Cx. tritaeniorhynchus. The tropics and subtropics, including southeastern Asia, Central Africa, southeastern North America and eastern South America, showed high habitat suitability for Cx. tritaeniorhynchus. Cx. tritaeniorhynchus is predicted to have a wider distribution in all the continents, especially in Western Europe and South America in the future under two extreme emission scenarios (SSP5-8.5 and SSP1-2.6). Targeted strategies for the control and prevention of Cx. tritaeniorhynchus should be further strengthened.
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Affiliation(s)
- Yixin Tong
- School of Public Health, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Center for Tropical Disease Research, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
| | - Honglin Jiang
- School of Public Health, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Center for Tropical Disease Research, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
| | - Ning Xu
- School of Public Health, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Center for Tropical Disease Research, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
| | - Zhengzhong Wang
- School of Public Health, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Center for Tropical Disease Research, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
| | - Ying Xiong
- School of Public Health, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Center for Tropical Disease Research, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
| | - Jiangfan Yin
- School of Public Health, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Center for Tropical Disease Research, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
| | - Junhui Huang
- School of Public Health, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Center for Tropical Disease Research, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
| | - Yue Chen
- School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, 600 Peter Morand Crescent, Ottawa, ON K1G 5Z3, Canada
| | - Qingwu Jiang
- School of Public Health, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Center for Tropical Disease Research, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
| | - Yibiao Zhou
- School of Public Health, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Key Laboratory of Public Health Safety, Fudan University, Ministry of Education, Building 8, 130 Dong’an Road, Shanghai 200032, China
- Center for Tropical Disease Research, Fudan University, Building 8, 130 Dong’an Road, Shanghai 200032, China
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Olagunju EA. Is the presence of mosquitoes an indicator of poor environmental sanitation? JOURNAL OF WATER AND HEALTH 2023; 21:385-401. [PMID: 37338318 PMCID: wh_2023_280 DOI: 10.2166/wh.2023.280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
The World Health Organization has designated mosquitoes as the most lethal animal since they are known to spread pathogen-transmitting organisms. Understanding the many environmental elements that contribute to the spread of these vectors is one of the many strategies used to stop them. If there are mosquitoes around people, it may indicate that there is not an appropriate environmental sanitation program in place in the community or region. Environmental sanitation involves improving any elements of the physical environment that could have a negative impact on a person's survival, health, or physical environment. Keywords containing 'Aedes,' 'Culex,' 'Anopheles,' 'dengue,' 'malaria,' 'yellow fever,' 'Zika,' 'West Nile,' 'chikungunya,' 'resident,' 'environment,' 'sanitation,' 'mosquito control,' and 'breeding sites' of published articles on PubMed, Google Scholar, and ResearchGate were reviewed. It was discovered that the general population should be involved in mosquito and mosquito-borne disease control. Collaboration between health professionals and the general population is essential. The purpose of this paper is to increase public awareness of environmental health issues related to diseases carried by mosquitoes.
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Affiliation(s)
- Emmanuel Ajibola Olagunju
- Department of Crop and Environmental Protection, Faculty of Agricultural Sciences, Ladoke Akintola University of Technology, Ogbomoso, Nigeria E-mail:
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8
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Coulibaly YI, Sangare M, Dolo H, Soumaoro L, Coulibaly SY, Dicko I, Diabaté AF, Diarra L, Coulibaly ME, Doumbia SS, Diallo AA, Dembele M, Koudou BG, Bockarie MJ, Kelly-Hope LA, Klion AD, Nutman TB. No evidence of lymphatic filariasis transmission in Bamako urban setting after three mass drug administration rounds. Parasitol Res 2022; 121:3243-3248. [PMID: 36066741 PMCID: PMC9556341 DOI: 10.1007/s00436-022-07648-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 08/30/2022] [Indexed: 11/25/2022]
Abstract
Lymphatic filariasis (LF) elimination activities started in Mali in 2005 in the most endemic areas and reached countrywide coverage in 2009. In 2004, the district of Bamako was endemic for LF with a prevalence of 1.5%. The current study was designed to determine LF endemicity level in the urban area of Bamako after three rounds of ivermectin and albendazole mass drug administration (MDA). A cross-sectional study was conducted in 2011 in Bamako city, consisting of human prevalence and entomological surveys. Volunteers aged 14 years and above were invited to participate and tested for evidence of Wuchereria bancrofti using night time blood thick smear microfilarial count and blood spots for LF antibodies using the SD BIOLINE Oncho/LF IgG4 Biplex rapid test (Ov16/Wb123). Mosquitoes were collected using CDC light and gravid traps and tested using molecular methods. Poolscreen software v2.0 was used to estimate vector transmission potential. Of the 899 volunteers, one (0.11%) was found to be positive for LF using the Oncho/LF IgG4 Biplex rapid test, and none was found to have Wuchereria bancrofti microfilariae. No mosquitoes were found infected among 6174 Culex spp. (85.2%), 16 Anopheles gambiae s.l. (An. gambiae s.l.) (0.2%), 26 Aedes spp. (0.4%), 858 Ceratopogonidae (11.8%) and 170 other insects not identified (2.3%) tested. Our data indicate that there was no active LF transmission in the low prevalence urban district of Bamako after three MDA rounds. These data helped the National LF programme move forward towards the elimination goal.
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Affiliation(s)
- Yaya Ibrahim Coulibaly
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali.,Dermatology Hospital of Bamako, Bamako, Mali
| | - Moussa Sangare
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali. .,Interdisciplinary School of Health Sciences
- Faculty of Health Sciences, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
| | - Housseini Dolo
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Lamine Soumaoro
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Siaka Yamoussa Coulibaly
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Ilo Dicko
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Abdoul Fatao Diabaté
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Lamine Diarra
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Michel Emmanuel Coulibaly
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Salif Seriba Doumbia
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Abdallah Amadou Diallo
- Mali - International Center of Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Massitan Dembele
- National Lymphatic Filariasis Elimination Program, Ministry of Health and Public Hygiene, Bamako, Mali
| | - Benjamin G Koudou
- Centre Suisse de Recherche Scientifiques en Côte d'Ivoire, 01 BP 1303 Abidjan 01, Abidjan, Côte d'Ivoire.,UFR Science de la Nature, Université Nangui Abrogoua, 02 BP 801 Abidjan 01, Abidjan, Côte d'Ivoire
| | | | - Louise A Kelly-Hope
- Centre for Neglected Tropical Diseases, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, UK.,Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Amy D Klion
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Thomas B Nutman
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
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Liu MD, Li CX, Cheng JX, Zhao TY. Spatial statistical and environmental correlation analyses on vector density, vector infection index and Japanese encephalitis cases at the village and pigsty levels in Liyi County, Shanxi Province, China. Parasit Vectors 2022; 15:171. [PMID: 35590422 PMCID: PMC9118647 DOI: 10.1186/s13071-022-05305-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 04/27/2022] [Indexed: 11/21/2022] Open
Abstract
Background In the eco-epidemiological context of Japanese encephalitis (JE), geo-environmental features influence the spatial spread of the vector (Culex tritaeniorhynchus, Giles 1901) density, vector infection, and JE cases. Methods In Liyi County, Shanxi Province, China, the spatial autocorrelation of mosquito vector density, vector infection indices, and JE cases were investigated at the pigsty and village scales. The map and Enhanced Thematic Mapper (ETM) remote sensing databases on township JE cases and geo-environmental features were combined in a Geographic Information System (GIS), and the connections among these variables were analyzed with regression and spatial analyses. Results At the pigsty level, the vector density but not the infection index of the vector was spatially autocorrelated. For the pigsty vector density, the cotton field area was positively related, whereas the road length and the distance between pigsties and gullies were negatively related. In addition, the vector infection index was correlated with the pigsty vector density (PVD) and the number of pigs. At the village level, the vector density, vector infection index, and number of JE cases were not spatially autocorrelated. In the study area, the geo-environmental features, vector density, vector infection index, and JE case number comprised the Geo-Environment-Vector-JE (GEVJ) intercorrelation net system. In this system, pig abundance and cotton area were positive factors influencing the vector density first. Second, the infection index was primarily influenced by the vector density. Lastly, the JE case number was determined by the vector infection index and the wheat area. Conclusions This study provided quantitative associations among geo-environmental features, vectors, and the incidence of JE in study sties, one typical northern Chinese JE epidemiological area without rice cultivation. The results highlighted the importance of using a diverse range of environmental management methods to control mosquito disease vectors and provided useful information for improving the control of vector mosquitoes and reducing the incidence of JE in the northern Chinese agricultural context. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05305-8.
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Affiliation(s)
- Mei-De Liu
- Academy of Military Medical Sciences State Key Laboratory of Pathogen and Biosecurity, Beijing, 100071, People's Republic of China
| | - Chun-Xiao Li
- Academy of Military Medical Sciences State Key Laboratory of Pathogen and Biosecurity, Beijing, 100071, People's Republic of China
| | - Jing-Xia Cheng
- Shanxi Centers for Disease Control and Prevention, Taiyuan, 030012, People's Republic of China
| | - Tong-Yan Zhao
- Academy of Military Medical Sciences State Key Laboratory of Pathogen and Biosecurity, Beijing, 100071, People's Republic of China.
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10
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Malaria prevention interventions beyond long-lasting insecticidal nets and indoor residual spraying in low- and middle-income countries: a scoping review. Malar J 2022; 21:31. [PMID: 35109848 PMCID: PMC8812253 DOI: 10.1186/s12936-022-04052-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 01/17/2022] [Indexed: 11/13/2022] Open
Abstract
Background Significant progress in malaria prevention during the past two decades has prompted increasing global dialogue on malaria elimination. Recent reviews on malaria strategies have focused mainly on long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), with little emphasis on other prevention methods. This article is a scoping review of literature on malaria prevention methods beyond LLINs and IRS in low- and middle-income countries (LMICs). Methods This scoping review found articles published between from 1994 to 2020. Studies were obtained from a search of the PubMed, the Cochrane Library and Social Science abstracts. Grey literature and manual search of secondary references was also done. The search strategy included all study designs but limited only to English. Three independent reviewers performed the selection and characterization of articles, and the data collected were synthesized qualitatively. Results A total of 10,112 studies were identified among which 31 met the inclusion criteria. The results were grouped by the 3 emerging themes of: housing design; mosquito repellents; and integrated vector control. Housing design strategies included closing eves, screening of houses including windows, doors and ceilings, while mosquito repellents were mainly spatial repellents, use of repellent plants, and use of plant-based oils. Integrated vector control included larvae source management. Evidence consistently shows that improving housing design reduced mosquito entry and malaria prevalence. Spatial repellents also showed promising results in field experiments, while evidence on repellent plants is limited and still emerging. Recent literature shows that IVM has been largely ignored in recent years in many LMICs. Some malaria prevention methods such as spatial repellents and IVM are shown to have the potential to target both indoor and outdoor transmission of malaria, which are both important aspects to consider to achieve malaria elimination in LMICs. Conclusion The scoping review shows that other malaria prevention strategies beyond LLINs and IRS have increasingly become important in LMICs. These methods have a significant role in contributing to malaria elimination in endemic countries if they are adequately promoted alongside other conventional approaches. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04052-6.
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11
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Nieto-Sanchez C, Dens S, Solomon K, Haile A, Yuan Y, Hawer T, Yewhalaw D, Addissie A, Grietens KP. Beyond eves and cracks: An interdisciplinary study of socio-spatial variation in urban malaria transmission in Ethiopia. PLOS GLOBAL PUBLIC HEALTH 2022; 2:e0000173. [PMID: 36962186 PMCID: PMC10021683 DOI: 10.1371/journal.pgph.0000173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 02/23/2022] [Indexed: 11/18/2022]
Abstract
During the past century, the global trend of reduced malaria transmission has been concurrent with increasing urbanization. Although urbanization has traditionally been considered beneficial for vector control, the adaptation of malaria vectors to urban environments has created concerns among scientific communities and national vector control programs. Since urbanization rates in Ethiopia are among the highest in the world, the Ethiopian government developed an initiative focused on building multi-storied units organized in condominium housing. This study aimed to develop an interdisciplinary methodological approach that integrates architecture, landscape urbanism, medical anthropology, and entomology to characterize exposure to malaria vectors in this form of housing in three condominiums in Jimma Town. Mosquitoes were collected using light trap catches (LTCs) both indoor and outdoor during 2019's rainy season. Architectural drawings and ethnographic research were superposed to entomological data to detect critical interactions between uses of the space and settlement conditions potentially affecting malaria vector abundance and distribution. A total of 34 anopheline mosquitoes comprising three species (Anopheles gambiae s.l, An. pharoensis and An. coustani complex) were collected during the three months of mosquito collection. Anopheles gambiae s.l, the principal malaria vector in Ethiopia, was the predominant species of all the anophelines collected. Distribution of mosquito breeding sites across scales (household, settlement, urban landscape) is explained by environmental conditions, socio-cultural practices involving modification of existing spaces, and systemic misfits between built environment and territory. Variations in mosquito abundance and distribution in this study were mainly related to standard building practices that ignore the original logics of the territory, deficiency of water and waste disposal management systems, and adaptations of the space to fit heterogeneous lifestyles of residents. Our results indicate that contextualizing malaria control strategies in relation to vector ecology, social dynamics determining specific uses of the space, as well as building and territorial conditions could strengthen current elimination efforts. Although individual housing remains a critical unit of research for vector control interventions, this study demonstrates the importance of studying housing settlements at communal level to capture systemic interactions impacting transmission at the household level and in outdoor areas.
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Affiliation(s)
- Claudia Nieto-Sanchez
- Department of Public Health, Unit of Socio-Ecological Health Research, Institute of Tropical Medicine, Antwerp, Belgium
| | - Stefanie Dens
- Witteveen+Bos Belgium N.V., Antwerp, Belgium
- Research Group for Urban Development, Faculty of Design Sciences, University of Antwerp, Antwerp, Belgium
| | - Kalkidan Solomon
- Department of Preventive Medicine, School of Public Health, Addis Ababa University, Addis Ababa, Ethiopia
| | - Asgedom Haile
- Ethiopian Institute of Architecture, Building Construction, and City Development (EiABC), Addis Ababa University, Addis Ababa, Ethiopia
| | - Yue Yuan
- Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | | | - Delenasaw Yewhalaw
- Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Adamu Addissie
- Department of Preventive Medicine, School of Public Health, Addis Ababa University, Addis Ababa, Ethiopia
| | - Koen Peeters Grietens
- Department of Public Health, Unit of Socio-Ecological Health Research, Institute of Tropical Medicine, Antwerp, Belgium
- Witteveen+Bos Belgium N.V., Antwerp, Belgium
- Research Group for Urban Development, Faculty of Design Sciences, University of Antwerp, Antwerp, Belgium
- Department of Preventive Medicine, School of Public Health, Addis Ababa University, Addis Ababa, Ethiopia
- Ethiopian Institute of Architecture, Building Construction, and City Development (EiABC), Addis Ababa University, Addis Ababa, Ethiopia
- Faculty of Medicine, University of British Columbia, Vancouver, Canada
- Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
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Zhou Y, Liu H, Leng P, Zhu J, Yao S, Zhu Y, Wu H. Analysis of the spatial distribution of Aedes albopictus in an urban area of Shanghai, China. Parasit Vectors 2021; 14:501. [PMID: 34565466 PMCID: PMC8474869 DOI: 10.1186/s13071-021-05022-8] [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: 02/06/2021] [Accepted: 09/14/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Aedes albopictus is a vector of major arboviral diseases and a primary pest in tropical and temperate regions of China. In most cities of China, the current monitoring system for the spread of Ae. albopictus is based on the subdistrict scale and does not consider spatial distribution for analysis of species density. Thus, the system is not sufficiently accurate for epidemic investigations, especially in large cities. METHODS This study used an improved surveillance program, with the mosquito oviposition trap (MOT) method, integrating the actual monitoring locations to investigate the temporal and spatial distribution of Ae. albopictus abundance in an urban area of Shanghai, China from 2018 to 2019. A total of 133 monitoring units were selected for surveillance of Ae. albopictus density in the study area, which was composed of 14 subdistricts. The vector abundance and spatial structure of Ae. albopictus were predicted using a binomial areal kriging model based on eight MOTs in each unit. Results were compared to the light trap (LT) method of the traditional monitoring scheme. RESULTS A total of 8,192 MOTs were placed in the study area in 2018, and 7917 (96.6%) were retrieved, with a positive rate of 6.45%. In 2019, 22,715 (97.0%) of 23,408 MOTs were recovered, with a positive rate of 5.44%. Using the LT method, 273 (93.5%) and 312 (94.5%) adult female Ae. albopictus were gathered in 2018 and 2019, respectively. The Ae. albopictus populations increased slowly from May, reached a peak in July, and declined gradually from September. The MOT positivity index (MPI) showed significant positive spatial autocorrelation across the study area, whereas LT collections indicated a nonsignificant spatial autocorrelation. The MPI was suitable for spatial interpolation using the binomial areal kriging model and showed different hot spots in different years. CONCLUSIONS The improved surveillance system integrated with a geographical information system (GIS) can improve our understanding of the spatial and temporal distribution of Ae. albopictus in urban areas and provide a practical method for decision-makers to implement vector control and mosquito management.
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Affiliation(s)
- Yibin Zhou
- Department of Infectious Disease Control, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, 200336 China
| | - Hongxia Liu
- Department of Infectious Disease Control, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, 200336 China
| | - Peien Leng
- Department of Infectious Disease Control, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, 200336 China
| | - Jiang Zhu
- Department of Infectious Disease Control, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, 200336 China
| | - Shenjun Yao
- Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241 China
| | - Yiyi Zhu
- Department of Infectious Disease Control, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, 200336 China
| | - Huanyu Wu
- Department of Infectious Disease Control, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, 200336 China
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Ethnomedicinal Use, Phytochemistry, and Pharmacology of Xylocarpus granatum J. Koenig. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2021; 2021:8922196. [PMID: 34504541 PMCID: PMC8423563 DOI: 10.1155/2021/8922196] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 08/07/2021] [Accepted: 08/10/2021] [Indexed: 11/18/2022]
Abstract
The mangrove plants are the potential sources of foods and remedies for people living in the forests and nearby communities. Xylocarpus granatum J. Koenig is traditionally used to treat various diseases including diarrhea, cholera, dysentery, fever, malaria, and viral infections, among others. To summarize critically the taxonomy, ethnomedicinal, phytochemistry, and pharmacological activities of X. granatum, information was collected from different databases. An up-to-date search (till June 2020) was carried out with the help of various scientific web resources from databases such as PubMed, Science Direct, Google Scholar, and various patent offices (e.g., WIPO, CIPO, and USPTO) using the keywords “Xylocarpus granatum” and then paired with ethnomedicinal use and phytochemical, phytochemistry, and pharmacological activity (in vitro, ex vivo, and in vivo studies). Findings revealed that seeds, fruits, stem bark, leaf, and twigs of X. granatum exhibited a wide range of key phytochemicals including limonoids, phragmalin, limonoid-based alkaloids, mexicanolides, protolimonoids, flavonols, and lactones. The plant possessed potent antioxidant, anticancer, antidiabetic, antimicrobial, antimalarial, antifeedant, and neuroprotective activities. No clinical studies have been reported in the databases. Ethnomedicinal assessment indicated the application of X. granatum in various fields of medical science specially to treat various human ailments, and this was attributed to the presence of enormous alkaloids as confirmed by pharmacological studies. However, to understand the mechanism of action in-depth studies are required. In view of these findings, more research is necessary to explore and characterize the chemical compounds and toxicological aspects of this medicinal mangrove plant. Overall, it can be stated that X. granatum may be one of the hopeful medicinal herbs for the treatment of various diseases in human beings.
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Doumbe-Belisse P, Kopya E, Ngadjeu CS, Sonhafouo-Chiana N, Talipouo A, Djamouko-Djonkam L, Awono-Ambene HP, Wondji CS, Njiokou F, Antonio-Nkondjio C. Urban malaria in sub-Saharan Africa: dynamic of the vectorial system and the entomological inoculation rate. Malar J 2021; 20:364. [PMID: 34493280 PMCID: PMC8424958 DOI: 10.1186/s12936-021-03891-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/20/2021] [Indexed: 12/11/2022] Open
Abstract
Sub-Saharan Africa is registering one of the highest urban population growth across the world. It is estimated that over 75% of the population in this region will be living in urban settings by 2050. However, it is not known how this rapid urbanization will affect vector populations and disease transmission. The present study summarizes findings from studies conducted in urban settings between the 1970s and 2020 to assess the effects of urbanization on the entomological inoculation rate pattern and anopheline species distribution. Different online databases such as PubMed, ResearchGate, Google Scholar, Google were screened. A total of 90 publications were selected out of 1527. Besides, over 200 additional publications were consulted to collate information on anopheline breeding habitats and species distribution in urban settings. The study confirms high malaria transmission in rural compared to urban settings. The study also suggests that there had been an increase in malaria transmission in most cities after 2003, which could also be associated with an increase in sampling, resources and reporting. Species of the Anopheles gambiae complex were the predominant vectors in most urban settings. Anopheline larvae were reported to have adapted to different aquatic habitats. The study provides updated information on the distribution of the vector population and the dynamic of malaria transmission in urban settings. The study also highlights the need for implementing integrated control strategies in urban settings.
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Affiliation(s)
- P Doumbe-Belisse
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - E Kopya
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - C S Ngadjeu
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - N Sonhafouo-Chiana
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Health Sciences, University of Buea, Cameroon, P.O. Box 63, Buea, Cameroon
| | - A Talipouo
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - L Djamouko-Djonkam
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Dschang Cameroon, P.O. Box 67, Dschang, Cameroon
| | - H P Awono-Ambene
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
| | - C S Wondji
- Vector Group Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK
| | - F Njiokou
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - C Antonio-Nkondjio
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun. .,Vector Group Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK.
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Mama CN, Nnaji CC, Nnam JP, Opata OC. Environmental burden of unprocessed solid waste handling in Enugu State, Nigeria. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:19439-19457. [PMID: 33398762 DOI: 10.1007/s11356-020-12265-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 12/28/2020] [Indexed: 06/12/2023]
Abstract
Improper waste management has assumed a worrisome dimension in cities across many developing countries. One of its commonest features is open dumps. Open dumps in Enugu and Nsukka were investigated in this study. Waste samples were collected from ten dumps located in low-income, low-to-middle income, and high-income zones of the study area. The composition of waste was determined following standard methods and results obtained subjected to statistical analyses. Selected open dumps were subjected to detailed inspection in order to identify possible environmental impacts. Soil samples were also collected from the top soil and subsoil (15 cm) of selected dumps and analyzed for As, Cd, Cr, Cu, Hg, Mn, Pb, Ni, Cd, and Zn. The sources of contamination were determined using the principal component analysis (PCA) and cluster analysis (CA). Results of heavy metal analyses were used to determine extent of soil pollution. Food waste ranged from 29.6 to 56.5% with an average of 42.2%. Analysis along income line showed a decline in the proportion of food and rubber waste from lower to high income. The order of heavy metals concentration in waste dump soils investigated was as follows: Mn > Zn > Cu > Cr > Pb > As > Ni > Cd > Hg. The pollution indices (PI) of the dumpsites ranged from 1.87 for Ni to 1634.6 for Cu in the topsoil, and 0.62 for Ni to 1354.74 for Cu in the subsoil, indicating a severe level of pollution. Pollution load index (PLI) ranged from 25.38 to 75.07 with a mean of 60.75 for the dump surface and from 51.46 to 21.7 with a mean of 33.86 below the dump soil. Forty-three percent (43%) of the topsoil and 40% of the subsoil exhibited ecological risk index values greater than 320, indicating extreme degree of ecological risk. The first principal and second principal components with 36% and 28.2% variance respectively represent the growing impact of electronic waste disposal, specifically mobile phones, personal computers, and other potable electronic devices with short life span on waste dumps. The third principal component (10.2%) represents input from households and other forms of chemicals such as insecticides, paints, and detergents.
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Affiliation(s)
- Cordelia Nnennaya Mama
- Department of Civil Engineering, University of Nigeria, Nsukka, Enugu State, 410001, Nigeria
| | - Chidozie Charles Nnaji
- Department of Civil Engineering, University of Nigeria, Nsukka, Enugu State, 410001, Nigeria.
- Faculty of Engineering and the Built Environment, University of Johannesburg, Johannesburg, South Africa.
| | - John P Nnam
- Department of Chemical and Environmental Technology, University of Valladolid, Valladolid, Spain
| | - Opata C Opata
- Department of Civil Engineering, University of Nigeria, Nsukka, Enugu State, 410001, Nigeria
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16
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Murindahabi MM, Takken W, Misago X, Niyituma E, Umupfasoni J, Hakizimana E, van Vliet AJH, Poortvliet PM, Mutesa L, Murindahabi NK, Koenraadt CJM. Monitoring mosquito nuisance for the development of a citizen science approach for malaria vector surveillance in Rwanda. Malar J 2021; 20:36. [PMID: 33423679 PMCID: PMC7798336 DOI: 10.1186/s12936-020-03579-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 12/31/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Many countries, including Rwanda, have mosquito monitoring programmes in place to support decision making in the fight against malaria. However, these programmes can be costly, and require technical (entomological) expertise. Involving citizens in data collection can greatly support such activities, but this has not yet been thoroughly investigated in a rural African context. METHODS Prior to the implementation of such a citizen-science approach, a household entomological survey was conducted in October-November 2017 and repeated one year later in Busoro and Ruhuha sectors, in southern and eastern province of Rwanda, respectively. The goal was to evaluate the perception of mosquito nuisance reported by citizens as a potential indicator for malaria vector hotspots. Firstly, mosquito abundance and species composition were determined using Centers for Disease Control and Prevention (CDC) light traps inside the houses. Secondly, household members were interviewed about malaria risk factors and their perceived level of mosquito nuisance. RESULTS Tiled roofs, walls made of mud and wood, as well as the number of occupants in the house were predictors for the number of mosquitoes (Culicidae) in the houses, while the presence of eaves plus walls made of mud and wood were predictors for malaria vector abundance. Perception of mosquito nuisance reported indoors tended to be significantly correlated with the number of Anopheles gambiae sensu lato (s.l.) and Culicidae collected indoors, but this varied across years and sectors. At the village level, nuisance also significantly correlated with An. gambiae s.l. and total mosquito density, but only in 2018 while not in 2017. CONCLUSIONS Perception of mosquito nuisance denoted in a questionnaire survey could be used as a global indicator of malaria vector hotspots. Hence, involving citizens in such activities can complement malaria vector surveillance and control.
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Affiliation(s)
- Marilyn Milumbu Murindahabi
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,College of Sciences and Technology, University of Rwanda, Kigali, Rwanda
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Xavier Misago
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Elias Niyituma
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Jackie Umupfasoni
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Emmanuel Hakizimana
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Arnold J H van Vliet
- Environmental Systems Analysis Group, Wageningen University & Research, Wageningen, The Netherlands
| | - P Marijn Poortvliet
- Strategic Communication Group, Wageningen University & Research, Wageningen, the Netherlands
| | - Leon Mutesa
- College of Medicine and Health Sciences, University of Rwanda, Kigali, Rwanda
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Lindsay SW, Davies M, Alabaster G, Altamirano H, Jatta E, Jawara M, Carrasco-Tenezaca M, von Seidlein L, Shenton FC, Tusting LS, Wilson AL, Knudsen J. Recommendations for building out mosquito-transmitted diseases in sub-Saharan Africa: the DELIVER mnemonic. Philos Trans R Soc Lond B Biol Sci 2020; 376:20190814. [PMID: 33357059 DOI: 10.1098/rstb.2019.0814] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In sub-Saharan Africa, most transmission of mosquito-transmitted diseases, such as malaria or dengue, occurs within or around houses. Preventing mosquito house entry and reducing mosquito production around the home would help reduce the transmission of these diseases. Based on recent research, we make key recommendations for reducing the threat of mosquito-transmitted diseases through changes to the built environment. The mnemonic, DELIVER, recommends the following best practices: (i) Doors should be screened, self-closing and without surrounding gaps; (ii) Eaves, the space between the wall and roof, should be closed or screened; (iii) houses should be Lifted above the ground; (iv) Insecticide-treated nets should be used when sleeping in houses at night; (v) houses should be Ventilated, with at least two large-screened windows to facilitate airflow; (vi) Environmental management should be conducted regularly inside and around the home; and (vii) Roofs should be solid, rather than thatch. DELIVER is a package of interventions to be used in combination for maximum impact. Simple changes to the built environment will reduce exposure to mosquito-transmitted diseases and help keep regions free from these diseases after elimination. This article is part of the theme issue 'Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Steven W Lindsay
- Department of Biosciences, Durham University, Durham DH1 3LE, UK
| | - Michael Davies
- Bartlett School Environment, Energy & Resources, Faculty of the Built Environment, University College London, London WC1H 0NN, UK
| | | | - Hector Altamirano
- Bartlett School Environment, Energy & Resources, Faculty of the Built Environment, University College London, London WC1H 0NN, UK
| | - Ebrima Jatta
- National Malaria Control Programme, Banjul, The Gambia
| | - Musa Jawara
- Medical Research Council Unit Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | | | - Lorenz von Seidlein
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Fiona C Shenton
- Department of Biosciences, Durham University, Durham DH1 3LE, UK
| | - Lucy S Tusting
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Anne L Wilson
- Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Jakob Knudsen
- The Royal Danish Academy of Fine Arts, School of Architecture, Design and Conservation, The School of Architecture, Copenhagen, Denmark
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18
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Buxton M, Machekano H, Gotcha N, Nyamukondiwa C, Wasserman RJ. Are Vulnerable Communities Thoroughly Informed on Mosquito Bio-Ecology and Burden? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:E8196. [PMID: 33171954 PMCID: PMC7672552 DOI: 10.3390/ijerph17218196] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/24/2020] [Accepted: 09/25/2020] [Indexed: 11/25/2022]
Abstract
Mosquitoes account for a significant burden of morbidity and mortality globally. Despite evidence of (1) imminent anthropogenic climate and environmental changes, (2) vector-pathogen spatio-temporal dynamics and (3) emerging and re-emerging mosquito borne infections, public knowledge on mosquito bio-ecology remain scant. In particular, knowledge, attitude and practices (KAPs) on mosquitoes are often neglected despite otherwise expensive remedial efforts against consequent infections and other indirect effects associated with disease burden. To gather baseline KAPs that identify gaps for optimising vector-borne disease control, we surveyed communities across endemic and non-endemic malaria sub-districts (Botswana). The study revealed limited knowledge of mosquitoes and their infections uniformly across endemic and non-endemic areas. In addition, a significant proportion of respondents were concerned about mosquito burdens, although their level of personal, indoor and environmental protection practices varied significantly across sub-districts. Given the limited knowledge displayed by the communities, this study facilitates bridging KAP gaps to minimise disease burdens by strengthening public education. Furthermore, it provides a baseline for future studies in mosquito bio-ecology and desirable control practices across differential spheres of the rural-urban lifestyle, with implications for enhanced livelihoods as a consequence of improved public health.
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Affiliation(s)
- Mmabaledi Buxton
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P. Bag 16, Palapye, Botswana; (H.M.); (N.G.); (C.N.); (R.J.W.)
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19
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Musiime AK, Smith DL, Kilama M, Geoffrey O, Kyagamba P, Rek J, Conrad MD, Nankabirwa JI, Arinaitwe E, Akol AM, Kamya MR, Dorsey G, Staedke SG, Drakeley C, Lindsay SW. Identification and characterization of immature Anopheles and culicines (Diptera: Culicidae) at three sites of varying malaria transmission intensities in Uganda. Malar J 2020; 19:221. [PMID: 32576188 PMCID: PMC7313098 DOI: 10.1186/s12936-020-03304-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/18/2020] [Indexed: 11/20/2022] Open
Abstract
Background Over the last two decades, there has been remarkable progress in malaria control in sub-Saharan Africa, due mainly to the massive deployment of long-lasting insecticidal nets and indoor residual spraying. Despite these gains, it is clear that in many situations, additional interventions are needed to further reduce malaria transmission. The World Health Organization (WHO) has promoted the Integrated Vector Management (IVM) approach through its Global Vector Control Response 2017–2030. However, prior roll-out of larval source management (LSM) as part of IVM, knowledge on ecology of larval aquatic habitats is required. Methods Aquatic habitats colonized by immature Anopheles and culicines vectors were characterized at three sites of low, medium and high malaria transmission in Uganda from October 2011 to June 2015. Larval surveys were conducted along transects in each site and aquatic habitats described according to type and size. Immature Anopheles, culicines and pupae from the described habitats were sampled using standard dipping methods to determine larval and pupae densities. Larvae were identified as anopheline or culicine, and counted. Pupae were not identified further. Binary logistic regression analysis was used to identify factors associated with the presence of immature Anopheles and culicines in each site. Results A total of 1205 larval aquatic habitats were surveyed and yielded a total of 17,028 anopheline larvae, 26,958 culicine larvae and 1189 pupae. Peaks in larval abundance occurred in all sites in March–May and August-October coinciding with the rainy seasons. Anopheles larvae were found in 52.4% (n = 251) of aquatic habitats in Tororo, a site of high transmission, 41.9% (n = 536) of habitats in Kanungu, a site with moderate malaria transmission, and 15.8% (n = 418) in Jinja, a site with low malaria transmission. The odds of finding larvae was highest in rice fields compared to pools in both Tororo (odds ratio, OR = 4.21, 95% CI 1.22–14.56, p = 0.02) and Kanungu (OR = 2.14, 95% CI 1.12–4.07, p = 0.02), while in Jinja the odd were highest in containers (OR = 4.55, 95% CI = 1.09–19.14, p = 0.03). In Kanungu, larvae were less likely to be found in containers compared to pools (OR = 0.26, 95% CI 0.09–0.66, p = 0.008) and river fringe (OR = 0.19, 95% CI 0.07–0.52, p = 0.001). Medium sized habitats were associated with high odds of finding larvae compared to small habitats (OR = 3.59, 95% CI 1.18–14.19, p = 0.039). Conclusions These findings show that immature Anopheles and culicines were common in areas of high and moderate transmission but were rare in areas of low transmission. Although immature Anopheles and culicines were found in all types of water bodies, they were most common in rice fields and less common in open drains and in river fringes. Methods are needed to reduce the aquatic stages of anopheline mosquitoes in human-made habitats, particularly rice fields.
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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
- Department of Health Metrics Sciences, University of Washington, Seattle, USA
| | - Maxwell Kilama
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Otto Geoffrey
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - John Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Melissa D Conrad
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, USA
| | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | | | - Anne M Akol
- Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Grant Dorsey
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, USA
| | - Sarah G Staedke
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
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20
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Ndiaye T, Sy M, Gaye A, Ndiaye D. Genetic polymorphism of Merozoite Surface Protein 1 (msp1) and 2 (msp2) genes and multiplicity of Plasmodium falciparum infection across various endemic areas in Senegal. Afr Health Sci 2019; 19:2446-2456. [PMID: 32127816 PMCID: PMC7040301 DOI: 10.4314/ahs.v19i3.19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Despite a significant decline in Senegal, malaria remains a burden in various parts of the country. Assessment of multiplicity of Plasmodium falciparum infection and genetic diversity of parasites population could help in monitoring of malaria control. OBJECTIVE To assess genetic diversity and multiplicity of infection in P. falciparum isolates from three areas in Senegal with different malaria transmissions. METHODS 136 blood samples were collected from patients with uncomplicated P. falciparum malaria in Pikine, Kedougou and Thies. Polymorphic loci of msp1 and 2 (Merozoite surface protein-1 and 2) genes were amplified by nested PCR. RESULTS For msp1gene, K1 allelic family was predominant with frequency of 71%. Concerning msp2 gene, IC3D7 allelic family was the most represented with frequency of 83%. Multiclonal isolates found were 36% and 31% for msp1et msp2 genes respectively. The MOI found in all areas was 2.56 and was statistically different between areas (P=0.024). Low to intermediate genetic diversity were found with heterozygosity range (He=0,394-0,637) and low genetic differentiation (Fst msp1= 0.011; Fst msp2=0.017) were observed between P. falciparum population within the country. CONCLUSION Low to moderate genetic diversity of P.falciparum strains and MOI disparities were found in Senegal.
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Affiliation(s)
- Tolla Ndiaye
- Laboratory of Parasitology/Mycology HALD, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Mouhamad Sy
- Laboratory of Parasitology/Mycology HALD, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Amy Gaye
- Laboratory of Parasitology/Mycology HALD, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Daouda Ndiaye
- Laboratory of Parasitology/Mycology HALD, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
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21
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Srividya A, Subramanian S, Sadanandane C, Vasuki V, Jambulingam P. Determinants of transmission hotspots and filarial infection in households after eight rounds of mass drug administration in India. Trop Med Int Health 2018; 23:1251-1258. [PMID: 30152049 DOI: 10.1111/tmi.13143] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Lymphatic filariasis (LF) elimination through mass drug administration (MDA) of DEC and albendazole have resulted in very low levels of infection in most endemic districts in India. But small pockets with residual microfilaraemia in the community and antigeneamia in children ('hotspots') are a cause of concern. We aimed to identify the determinants of such transmission hotspots and filarial infection in households using data from 33 communities. METHODS The filariasis vector Culex quinquefasciatus was collected from 627 randomly selected households using gravid traps. Parallel data on environmental, entomological, demographical, socio-economical and behavioural factors were analysed to identify the determinants of hotspots and household-level infection. RESULTS Hotspots and non-hotspots did not differ significantly in terms of socio-economical and behavioural aspects, but did differ in terms of demographical and environmental factors. Logistic regression revealed that tiled and concrete houses increased the risk of an area being a hotspot by 2.0 and 2.9 times respectively. Presence of Culex breeding habitats was significantly associated with elevated risk of being a hotspot. Proximity of U-drains to a house increased the risk of filarial infection 5.8 times. CONCLUSIONS An environment suitable to Culex breeding influences continued transmission despite eight rounds of MDA, particularly in hotspots. Proximity to U-drains increases the risk of infection in households. Implementing localised vector control measures may help interrupt low-level transmission, thereby reducing the risk of resurgence in the absence of MDA.
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Affiliation(s)
- A Srividya
- ICMR-Vector Control Research Centre, Puducherry, India
| | - S Subramanian
- ICMR-Vector Control Research Centre, Puducherry, India
| | - C Sadanandane
- ICMR-Vector Control Research Centre, Puducherry, India
| | - V Vasuki
- ICMR-Vector Control Research Centre, Puducherry, India
| | - P Jambulingam
- ICMR-Vector Control Research Centre, Puducherry, India
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22
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Makungu C, Stephen S, Kumburu S, Govella NJ, Dongus S, Hildon ZJL, Killeen GF, Jones C. Informing new or improved vector control tools for reducing the malaria burden in Tanzania: a qualitative exploration of perceptions of mosquitoes and methods for their control among the residents of Dar es Salaam. Malar J 2017; 16:410. [PMID: 29020970 PMCID: PMC5637339 DOI: 10.1186/s12936-017-2056-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 10/05/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The effectiveness of malaria prevention with long-lasting insecticidal nets and indoor residual spraying is limited by emerging insecticide resistance, evasive mosquito behaviours that include outdoor biting, sub-optimal implementation and inappropriate use. New vector control interventions are required and their potential effectiveness will be enhanced if existing household perceptions and practices are integrated into intervention design. METHODS This qualitative descriptive study used focus groups discussions, in-depth interviews and photovoice methods to explore mosquito control perceptions and practices among residents in four study sites in Dar es Salaam, Tanzania. RESULTS Mosquitoes were perceived as a growing problem, directly attributed to widespread environmental deterioration and lack of effective mosquito control interventions. Malaria and nuisance biting were perceived as the main problem caused by mosquitoes. Breeding sites were clearly distinguished from resting sites but residents did not differentiate between habitats producing malaria vector mosquitoes and others producing mostly nuisance mosquitoes. The most frequently mentioned protection methods in the wealthiest locations were bed nets, aerosol insecticide sprays, window screens, and fumigation, while bed nets were most frequently mentioned and described as 'part of the culture' in the least wealthy locations. Mosquito-proofed housing was consistently viewed as desirable, but considered unaffordable outside wealthiest locations. Slapping and covering up with clothing were most commonly used to prevent biting outdoors. Despite their utility outdoors, topical repellents applied to the skin were considered expensive, and viewed with suspicion due to perceived side effects. Improving the local environment was the preferred method for preventing outdoor biting. Affordability, effectiveness, availability, practicality, as well as social influences, such as government recommendations, socialization and internalization (familiarization and habit) were described as key factors influencing uptake. CONCLUSIONS Outdoor transmission is widely accepted as an obstacle to malaria elimination. Larval source management, targeting both malaria vectors and nuisance-biting mosquitoes, is the preferred method for mosquito control among the residents of Dar es Salaam and should be prioritized for development alongside new methods for outdoor personal protection. Even if made available, effective and affordable, these additional interventions may require time and user experience to achieve positive reputations and trustworthiness.
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Affiliation(s)
- Christina Makungu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Kiko Avenue, Mikocheni, PO Box 78373, Dar Es Salaam, United Republic of Tanzania
| | - Stephania Stephen
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Kiko Avenue, Mikocheni, PO Box 78373, Dar Es Salaam, United Republic of Tanzania
| | - Salome Kumburu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Kiko Avenue, Mikocheni, PO Box 78373, Dar Es Salaam, United Republic of Tanzania
| | - Nicodem J. Govella
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Kiko Avenue, Mikocheni, PO Box 78373, Dar Es Salaam, United Republic of Tanzania
| | - Stefan Dongus
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Kiko Avenue, Mikocheni, PO Box 78373, Dar Es Salaam, United Republic of Tanzania
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L35QA UK
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 4003 Basel, Switzerland
| | - Zoe Jane-Lara Hildon
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Kiko Avenue, Mikocheni, PO Box 78373, Dar Es Salaam, United Republic of Tanzania
- London School of Hygiene and Tropical Medicine, London, UK
- Johns Hopkins Center for Communication Programs, Johns Hopkins University, Baltimore, USA
| | - Gerry F. Killeen
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Kiko Avenue, Mikocheni, PO Box 78373, Dar Es Salaam, United Republic of Tanzania
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L35QA UK
| | - Caroline Jones
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- London School of Hygiene and Tropical Medicine, London, UK
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23
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Castro MC. Malaria Transmission and Prospects for Malaria Eradication: The Role of the Environment. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a025601. [PMID: 28490534 DOI: 10.1101/cshperspect.a025601] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Environmental factors affect the transmission intensity, seasonality, and geographical distribution of malaria, and together with the vector, the human, and the parasite compose the malaria system. Strategies that alter the environment are among the oldest interventions for malaria control, but currently are not the most prominent despite historical evidence of their effectiveness. The importance of environmental factors, the role they play considering the current goals of malaria eradication, the different strategies that can be adopted, and the current challenges for their implementation are discussed. As malaria elimination/eradication takes a prominent place in the health agenda, an integrated action, addressing all elements of the malaria system, which contributes to improved knowledge and to building local capacity and that brings about positive effects to the health of the local population has the greatest chance to produce fast, effective, and sustainable results.
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Affiliation(s)
- Marcia C Castro
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115
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24
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Bangert M, Molyneux DH, Lindsay SW, Fitzpatrick C, Engels D. The cross-cutting contribution of the end of neglected tropical diseases to the sustainable development goals. Infect Dis Poverty 2017; 6:73. [PMID: 28372566 PMCID: PMC5379574 DOI: 10.1186/s40249-017-0288-0] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 03/16/2017] [Indexed: 01/14/2023] Open
Abstract
The Sustainable Development Goals (SDGs) call for an integrated response, the kind that has defined Neglected Tropical Diseases (NTDs) efforts in the past decade.NTD interventions have the greatest relevance for SDG3, the health goal, where the focus on equity, and its commitment to reaching people in need of health services, wherever they may live and whatever their circumstances, is fundamentally aligned with the target of Universal Health Coverage. NTD interventions, however, also affect and are affected by many of the other development areas covered under the 2030 Agenda. Strategies such as mass drug administration or the programmatic integration of NTD and WASH activities (SDG6) are driven by effective global partnerships (SDG17). Intervention against the NTDs can also have an impact on poverty (SDG1) and hunger (SDG2), can improve education (SDG4), work and economic growth (SDG8), thereby reducing inequalities (SDG10). The community-led distribution of donated medicines to more than 1 billion people reinforces women's empowerment (SDG5), logistics infrastructure (SDG9) and non-discrimination against disability (SDG16). Interventions to curb mosquito-borne NTDs contribute to the goals of urban sustainability (SDG11) and resilience to climate change (SDG13), while the safe use of insecticides supports the goal of sustainable ecosystems (SDG15). Although indirectly, interventions to control water- and animal-related NTDs can facilitate the goals of small-scale fishing (SDG14) and sustainable hydroelectricity and biofuels (SDG7).NTDs proliferate in less developed areas in countries across the income spectrum, areas where large numbers of people have little or no access to adequate health care, clean water, sanitation, housing, education, transport and information. This scoping review assesses how in this context, ending the epidemic of the NTDs can impact and improve our prospects of attaining the SDGs.
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Affiliation(s)
- Mathieu Bangert
- Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland
| | - David H. Molyneux
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Christopher Fitzpatrick
- Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland
| | - Dirk Engels
- Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland
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25
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Stoler J, Awandare GA. Febrile illness diagnostics and the malaria-industrial complex: a socio-environmental perspective. BMC Infect Dis 2016; 16:683. [PMID: 27855644 PMCID: PMC5114833 DOI: 10.1186/s12879-016-2025-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 11/14/2016] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Global prioritization of single-disease eradication programs over improvements to basic diagnostic capacity in the Global South have left the world unprepared for epidemics of chikungunya, Ebola, Zika, and whatever lies on the horizon. The medical establishment is slowly realizing that in many parts of sub-Saharan Africa (SSA), particularly urban areas, up to a third of patients suffering from acute fever do not receive a correct diagnosis of their infection. MAIN BODY Malaria is the most common diagnosis for febrile patients in low-resource health care settings, and malaria misdiagnosis has soared due to the institutionalization of malaria as the primary febrile illness of SSA by international development organizations and national malaria control programs. This has inadvertently created a "malaria-industrial complex" and historically obstructed our complete understanding of the continent's complex communicable disease epidemiology, which is currently dominated by a mélange of undiagnosed febrile illnesses. We synthesize interdisciplinary literature from Ghana to highlight the complexity of communicable disease care in SSA from biomedical, social, and environmental perspectives, and suggest a way forward. CONCLUSION A socio-environmental approach to acute febrile illness etiology, diagnostics, and management would lead to substantial health gains in Africa, including more efficient malaria control. Such an approach would also improve global preparedness for future epidemics of emerging pathogens such as chikungunya, Ebola, and Zika, all of which originated in SSA with limited baseline understanding of their epidemiology despite clinical recognition of these viruses for many decades. Impending ACT resistance, new vaccine delays, and climate change all beckon our attention to proper diagnosis of fevers in order to maximize limited health care resources.
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Affiliation(s)
- Justin Stoler
- Department of Geography and Regional Studies, University of Miami, Coral Gables, FL USA
- Department of Public Health Sciences, Miller School of Medicine, University of Miami, Miami, FL USA
- Abess Center for Ecosystem Science and Policy, University of Miami, Coral Gables, FL USA
| | - Gordon A. Awandare
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Ghana
- Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Ghana
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26
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Govella NJ, Maliti DF, Mlwale AT, Masallu JP, Mirzai N, Johnson PCD, Ferguson HM, Killeen GF. An improved mosquito electrocuting trap that safely reproduces epidemiologically relevant metrics of mosquito human-feeding behaviours as determined by human landing catch. Malar J 2016; 15:465. [PMID: 27618941 PMCID: PMC5020444 DOI: 10.1186/s12936-016-1513-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/02/2016] [Indexed: 12/02/2022] Open
Abstract
Background Reliable quantification of mosquito host—seeking behaviours is required to determine the efficacy of vector control methods. For malaria, the gold standard approach remains the risky human landing catch (HLC). Here compare the performance of an improved prototype of the mosquito electrocuting grid trap (MET) as a safer alternative with HLC for measuring malaria vector behaviour in Dar es Salaam, Tanzania. Methods Mosquito trapping was conducted at three sites within Dar es Salaam representing a range of urbanicity over a 7-month period (December 2012–July 2013, 168 sampling nights). At each site, sampling was conducted in a block of four houses, with two houses being allocated to HLC and the other to MET on each night of study. Sampling was conducted both indoors and outdoors (from 19:00 to 06:00 each night) at all houses, with trapping method (HLC and MET) being exchanged between pairs of houses at each site using a crossover design. Results The MET caught significantly more Anopheles gambiae sensu lato than the HLC, both indoors (RR [95 % confidence interval (CI)]) = 1.47 [1.23–1.76], P < 0.0001 and outdoors = 1.38 [1.14–1.67], P < 0.0001). The sensitivity of MET compared with HLC did not detectably change over the course of night for either An. gambiae s.l. (OR [CI]) = 1.01 [0.94–1.02], P = 0.27) or Culex spp. (OR [CI]) = 0.99 [0.99–1.0], P = 0.17) indoors and declined only slightly outdoors: An. gambiae s.l. (OR [CI]) = 0.92 [0.86–0.99], P = 0.04), and Culex spp. (OR [CI]) = 0.99 [0.98–0.99], P = 0.03). MET-based estimates of the proportions of mosquitoes caught indoors (Pi) or during sleeping hours (Pfl), as well as the proportion of human exposure to bites that would otherwise occurs indoors (πi), were statistically indistinguishable from those based on HLC for An. gambiae s.l. (P = 0.43, 0.07 and 0.48, respectively) and Culex spp. (P = 0.76, 0.24 and 0.55, respectively). Conclusions This improved MET prototype is highly sensitive tool that accurately quantifies epidemiologically-relevant metrics of mosquito biting densities, behaviours and human exposure distribution. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1513-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nicodem J Govella
- Environmental Health and Ecological Sciences Thematic Group, Coordination Office, Ifakara Health Institute, PO Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania.
| | - Deodatus F Maliti
- Environmental Health and Ecological Sciences Thematic Group, Coordination Office, Ifakara Health Institute, PO Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania.,College of Medical, Veterinary and Life Sciences, Boyd Orr Centre for Population and Ecosystem Health, University of Glasgow, Glasgow, UK
| | - Amos T Mlwale
- Environmental Health and Ecological Sciences Thematic Group, Coordination Office, Ifakara Health Institute, PO Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania
| | - John P Masallu
- Environmental Health and Ecological Sciences Thematic Group, Coordination Office, Ifakara Health Institute, PO Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania
| | - Nosrat Mirzai
- Bioelectronics Unit, University of Glasgow, Graham Kerr Building, Glasgow, G12 8QQ, UK
| | - Paul C D Johnson
- College of Medical, Veterinary and Life Sciences, Boyd Orr Centre for Population and Ecosystem Health, University of Glasgow, Glasgow, UK
| | - Heather M Ferguson
- College of Medical, Veterinary and Life Sciences, Boyd Orr Centre for Population and Ecosystem Health, University of Glasgow, Glasgow, UK
| | - Gerry F Killeen
- Environmental Health and Ecological Sciences Thematic Group, Coordination Office, Ifakara Health Institute, PO Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania.,Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
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27
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Castro MC, Maheu-Giroux M, Chiyaka C, Singer BH. Malaria Incidence Rates from Time Series of 2-Wave Panel Surveys. PLoS Comput Biol 2016; 12:e1005065. [PMID: 27509368 PMCID: PMC4980052 DOI: 10.1371/journal.pcbi.1005065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 07/18/2016] [Indexed: 11/25/2022] Open
Abstract
Methodology to estimate malaria incidence rates from a commonly occurring form of interval-censored longitudinal parasitological data—specifically, 2-wave panel data—was first proposed 40 years ago based on the theory of continuous-time homogeneous Markov Chains. Assumptions of the methodology were suitable for settings with high malaria transmission in the absence of control measures, but are violated in areas experiencing fast decline or that have achieved very low transmission. No further developments that can accommodate such violations have been put forth since then. We extend previous work and propose a new methodology to estimate malaria incidence rates from 2-wave panel data, utilizing the class of 2-component mixtures of continuous-time Markov chains, representing two sub-populations with distinct behavior/attitude towards malaria prevention and treatment. Model identification, or even partial identification, requires context-specific a priori constraints on parameters. The method can be applied to scenarios of any transmission intensity. We provide an application utilizing data from Dar es Salaam, an area that experienced steady decline in malaria over almost five years after a larviciding intervention. We conducted sensitivity analysis to account for possible sampling variation in input data and model assumptions/parameters, and we considered differences in estimates due to submicroscopic infections. Results showed that, assuming defensible a priori constraints on model parameters, most of the uncertainty in the estimated incidence rates was due to sampling variation, not to partial identifiability of the mixture model for the case at hand. Differences between microscopy- and PCR-based rates depend on the transmission intensity. Leveraging on a method to estimate incidence rates from 2-wave panel data under any transmission intensity, and from the increasing availability of such data, there is an opportunity to foster further methodological developments, particularly focused on partial identifiability and the diversity of a priori parameter constraints associated with different human-ecosystem interfaces. As a consequence there can be more nuanced planning and evaluation of malaria control programs than heretofore. Incidence rates measure the transitions between the states of noninfected to infected per unit of time and per person at risk. Usually calculated from longitudinal observations, they provide an indication of how rapidly a disease develops in a population over time. In the context of malaria, longitudinal data on infection status are obtained through consecutive survey rounds, separated by a certain time interval. Depending on the length of the interval, some changes of infection status may be missed, and thus only uncensored information would be available. Methodology to calculate incidence rates from this type of data was first proposed in 1976, but its assumptions were not applicable to low transmission settings, particularly in the presence of control measures. No alternative methodology has been proposed in the past 40 years, limiting attempts to obtain estimates of incidence rates in the current scenario of declining malaria transmission worldwide. In this paper we address this gap and introduce new methodology to estimate malaria incidence rates from longitudinal data that can be applied to settings with any transmission level. We provide a complete example of the method, including sensitivity analysis, and an assessment of possible differences between data based on microscopy vs. PCR diagnostics. To facilitate replication and wide use of the method, we make available a programming code in R language and the example dataset.
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Affiliation(s)
- Marcia C. Castro
- Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America
- * E-mail: (MCC); (BHS)
| | - Mathieu Maheu-Giroux
- Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Christinah Chiyaka
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom
| | - Burton H. Singer
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- * E-mail: (MCC); (BHS)
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Kabaria CW, Molteni F, Mandike R, Chacky F, Noor AM, Snow RW, Linard C. Mapping intra-urban malaria risk using high resolution satellite imagery: a case study of Dar es Salaam. Int J Health Geogr 2016; 15:26. [PMID: 27473186 PMCID: PMC4967308 DOI: 10.1186/s12942-016-0051-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 06/27/2016] [Indexed: 11/30/2022] Open
Abstract
Background With more than half of Africa’s population expected to live in urban settlements by 2030, the burden of malaria among urban populations in Africa continues to rise with an increasing number of people at risk of infection. However, malaria intervention across Africa remains focused on rural, highly endemic communities with far fewer strategic policy directions for the control of malaria in rapidly growing African urban settlements. The complex and heterogeneous nature of urban malaria requires a better understanding of the spatial and temporal patterns of urban malaria risk in order to design effective urban malaria control programs. In this study, we use remotely sensed variables and other environmental covariates to examine the predictability of intra-urban variations of malaria infection risk across the rapidly growing city of Dar es Salaam, Tanzania between 2006 and 2014. Methods High resolution SPOT satellite imagery was used to identify urban environmental factors associated malaria prevalence in Dar es Salaam. Supervised classification with a random forest classifier was used to develop high resolution land cover classes that were combined with malaria parasite prevalence data to identify environmental factors that influence localized heterogeneity of malaria transmission and develop a high resolution predictive malaria risk map of Dar es Salaam. Results Results indicate that the risk of malaria infection varied across the city. The risk of infection increased away from the city centre with lower parasite prevalence predicted in administrative units in the city centre compared to administrative units in the peri-urban suburbs. The variation in malaria risk within Dar es Salaam was shown to be influenced by varying environmental factors. Higher malaria risks were associated with proximity to dense vegetation, inland water and wet/swampy areas while lower risk of infection was predicted in densely built-up areas. Conclusions The predictive maps produced can serve as valuable resources for municipal councils aiming to shrink the extents of malaria across cities, target resources for vector control or intensify mosquito and disease surveillance. The semi-automated modelling process developed can be replicated in other urban areas to identify factors that influence heterogeneity in malaria risk patterns and detect vulnerable zones. There is a definite need to expand research into the unique epidemiology of malaria transmission in urban areas for focal elimination and sustained control agendas. Electronic supplementary material The online version of this article (doi:10.1186/s12942-016-0051-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Caroline W Kabaria
- Spatial Health Metrics Group, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya.
| | - Fabrizio Molteni
- National Malaria Control Programme, Ministry of Health and Social Welfare, Dar es Salaam, Tanzania.,Swiss Tropical and Public Health Institute, Dar es Salaam, Tanzania
| | - Renata Mandike
- National Malaria Control Programme, Ministry of Health and Social Welfare, Dar es Salaam, Tanzania
| | - Frank Chacky
- National Malaria Control Programme, Ministry of Health and Social Welfare, Dar es Salaam, Tanzania
| | - Abdisalan M Noor
- Spatial Health Metrics Group, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Robert W Snow
- Spatial Health Metrics Group, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Catherine Linard
- Department of Geography, Université de Namur, Rue de Bruxelles 61, 5000, Namur, Belgium.,Biological Control and Spatial Ecology, Université Libre de Bruxelles CP160/12, Av. F.D. Roosevelt 50, 1050, Brussels, Belgium
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29
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Msellemu D, Namango HI, Mwakalinga VM, Ntamatungiro AJ, Mlacha Y, Mtema ZJ, Kiware S, Lobo NF, Majambere S, Dongus S, Drakeley CJ, Govella NJ, Chaki PP, Killeen GF. The epidemiology of residual Plasmodium falciparum malaria transmission and infection burden in an African city with high coverage of multiple vector control measures. Malar J 2016; 15:288. [PMID: 27216734 PMCID: PMC4877954 DOI: 10.1186/s12936-016-1340-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 05/11/2016] [Indexed: 12/11/2022] Open
Abstract
Background In the Tanzanian city of Dar es Salaam, high coverage of long-lasting insecticidal nets (LLINs), larvicide application (LA) and mosquito-proofed housing, was complemented with improved access to artemisinin-based combination therapy and rapid diagnostic tests by the end of 2012. Methods Three rounds of city-wide, cluster-sampled cross-sectional surveys of malaria parasite infection status, spanning 2010 to 2012, were complemented by two series of high-resolution, longitudinal surveys of vector density. Results Larvicide application using a granule formulation of Bacillus thuringiensis var. israelensis (Bti) had no effect upon either vector density (P = 0.820) or infection prevalence (P = 0.325) when managed by a private-sector contractor. Infection prevalence rebounded back to 13.8 % in 2010, compared with <2 % at the end of a previous Bti LA evaluation in 2008. Following transition to management by the Ministry of Health and Social Welfare (MoHSW), LA consistently reduced vector densities, first using the same Bti granule in early 2011 [odds ratio (OR) (95 % confidence interval (CI)) = 0.31 (0.14, 0.71), P = 0.0053] and then a pre-diluted aqueous suspension formulation from mid 2011 onwards [OR (95 % CI) = 0.15 (0.07, 0.30), P ≪ 0.000001]. While LA by MoHSW with the granule formulation was associated with reduced infection prevalence [OR (95 % CI) = 0.26 (0.12, 0.56), P = 0.00040], subsequent liquid suspension use, following a mass distribution to achieve universal coverage of LLINs that reduced vector density [OR (95 % CI) = 0.72 (0.51, 1.01), P = 0.057] and prevalence [OR (95 % CI) = 0.80 (0.69, 0.91), P = 0.0013], was not associated with further prevalence reduction (P = 0.836). Sleeping inside houses with complete window screens only reduced infection risk [OR (95 % CI) = 0.71 (0.62, 0.82), P = 0.0000036] if the evenings and mornings were also spent indoors. Furthermore, infection risk was only associated with local vector density [OR (95 % CI) = 6.99 (1.12, 43.7) at one vector mosquito per trap per night, P = 0.037] among the minority (14 %) of households lacking screening. Despite attenuation of malaria transmission and immunity, 88 % of infected residents experienced no recent fever, only 0.4 % of these afebrile cases had been treated for malaria, and prevalence remained high (9.9 %) at the end of the study. Conclusions While existing vector control interventions have dramatically attenuated malaria transmission in Dar es Salaam, further scale-up and additional measures to protect against mosquito bites outdoors are desirable. Accelerated elimination of chronic human infections persisting at high prevalence will require active, population-wide campaigns with curative drugs. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1340-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Daniel Msellemu
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Hagai I Namango
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Victoria M Mwakalinga
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Alex J Ntamatungiro
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Yeromin Mlacha
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Zacharia J Mtema
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Samson Kiware
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Mathematics, Statistics and Computer Science, Marquette University, Milwaukee, WI, USA
| | - Neil F Lobo
- Eck Institute for Global Health, Notre Dame University, Notre Dame, IN, USA
| | - Silas Majambere
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Stefan Dongus
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Christopher J Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Nicodem J Govella
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Prosper P Chaki
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Gerry F Killeen
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania. .,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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Eneh LK, Okal MN, Borg-Karlson AK, Fillinger U, Lindh JM. Gravid Anopheles gambiae sensu stricto avoid ovipositing in Bermuda grass hay infusion and it's volatiles in two choice egg-count bioassays. Malar J 2016; 15:276. [PMID: 27177033 PMCID: PMC4866018 DOI: 10.1186/s12936-016-1330-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 05/05/2016] [Indexed: 11/23/2022] Open
Abstract
Background A number of mosquito species in the Culex and Aedes genera prefer to lay eggs in Bermuda grass (Cynodon dactylon) hay infusions compared to water alone. These mosquitoes are attracted to volatile compounds from the hay infusions making the infusions effective baits in gravid traps used for monitoring vectors of arboviral and filarial pathogens. Since Bermuda grass is abundant and widespread, it is plausible to explore infusions made from it as a potential low cost bait for outdoor monitoring of the elusive malaria vector Anopheles gambiae s.s. Methods This study investigated preferential egg laying of individual An. gambiae s.s. in hay infusion or in tap water treated with volatiles detected in hay infusion headspace compared to tap water alone, using two-choice egg-count bioassays. Infusions were prepared by mixing 90 g of dried Bermuda grass (hay) with 24 L of unchlorinated tap water in a bucket, and leaving it for 3 days at ambient temperature and humidity. The volatiles in the headspace of the hay infusion were sampled with Tenax TA traps for 20 h and analysed using gas chromatography coupled to mass spectrometry. Results In total, 18 volatiles were detected in the infusion headspace. Nine of the detected compounds and nonanal were selected for bioassays. Eight of the selected compounds have previously been suggested to attract/stimulate egg laying in An. gambiaes.s. Gravid females were significantly (p < 0.05) less likely to lay eggs in hay infusion dilutions of 25, 50 and 100 % and in tap water containing any of six compounds (3-methylbutanol, phenol, 4-methylphenol, nonanal, indole, and 3-methylindole) compared to tap water alone. The oviposition response to 10 % hay infusion or any one of the remaining four volatiles (4-hepten-1-ol, phenylmethanol, 2-phenylethanol, or 4-ethylphenol) did not differ from that in tap water. Conclusions Anopheles gambiae s.s. prefers to lay eggs in tap water rather than Bermuda grass hay infusion. This avoidance of the hay infusion appears to be mediated by volatile organic compounds from the infusion. It is, therefore, unlikely that Bermuda grass hay infusion as formulated and used in gravid traps for Culex and Aedes mosquitoes will be suitable baits for monitoring gravid An. gambiae s.s.
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Affiliation(s)
- Lynda K Eneh
- Chemical Ecology, Department of Chemistry, School of Chemical Science and Engineering, Royal Institute of Technology, Stockholm, Sweden
| | - Michael N Okal
- International Centre of Insect Physiology and Ecology, Thomas Odhiambo Campus, Mbita, Kenya. .,Disease Control Department, London School of Hygiene & Tropical Medicine, London, UK.
| | - Anna-Karin Borg-Karlson
- Chemical Ecology, Department of Chemistry, School of Chemical Science and Engineering, Royal Institute of Technology, Stockholm, Sweden
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology, Thomas Odhiambo Campus, Mbita, Kenya.,Disease Control Department, London School of Hygiene & Tropical Medicine, London, UK
| | - Jenny M Lindh
- Chemical Ecology, Department of Chemistry, School of Chemical Science and Engineering, Royal Institute of Technology, Stockholm, Sweden
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31
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Kouassi BL, de Souza DK, Goepogui A, Narh CA, King SA, Mamadou BS, Diakité L, Dadzie SK, Boakye DA, Utzinger J, Bockarie MJ, Koudou BG. Assessing the presence of Wuchereria bancrofti in vector and human populations from urban communities in Conakry, Guinea. Parasit Vectors 2015; 8:492. [PMID: 26410739 PMCID: PMC4583765 DOI: 10.1186/s13071-015-1077-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 09/08/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Global Programme to Eliminate Lymphatic Filariasis was launched in 2000 with the goal of interrupting transmission of lymphatic filariasis (LF) through multiple rounds of mass drug administration (MDA). In Guinea, there is evidence of ongoing LF transmission, but little is known about the most densely populated parts of the country, including the capital Conakry. In order to guide the LF control and elimination efforts, serological and entomological surveys were carried out to determine whether or not LF transmission occurs in Conakry. METHODS The prevalence of circulating filarial antigen (CFA) of Wuchereria bancrofti was assessed by an immuno-chromatography test (ICT) in people recruited from all five districts of Conakry. Mosquitoes were collected over a 1-year period, in 195 households in 15 communities. A proportion of mosquitoes were analysed for W. bancrofti, using dissection, loop-mediated isothermal amplification (LAMP) assay and conventional polymerase chain reaction (PCR). RESULTS CFA test revealed no infection in the 611 individuals examined. A total of 14,334 mosquitoes were collected; 14,135 Culex (98.6 %), 161 Anopheles (1.1 %) and a few other species. Out of 1,312 Culex spp. (9.3 %) and 51 An. gambiae (31.7 %) dissected, none was infected with any stage of the W. bancrofti parasite. However, the LAMP assay revealed that 1.8 % of An. gambiae and 0.31 % of Culex spp. were positive, while PCR determined respective prevalences of 0 % and 0.19 %. CONCLUSIONS This study revealed the presence of W. bancrofti DNA in mosquitoes, despite the apparent absence of infection in the human population. Although MDA interventions are not recommended where the prevalence of ICT is below 1 %, the entomological results are suggestive of the circulation of the parasite in the population of Conakry. Therefore, rigorous surveillance is still warranted so that LF transmission in Conakry would be identified rapidly and adequate responses being implemented.
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Affiliation(s)
- Bernard L Kouassi
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire.,Unité de Formation et de Recherche Science de la Nature, Université Nangui Abrogoua, Abidjan, Côte d'Ivoire.,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Dziedzom K de Souza
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Andre Goepogui
- Programme National de Lutte contre l'Onchocercose, le Trachome et les autres Maladies Tropicales Négligées, Ministère de la Santé Publique, Conakry, Guinea
| | - Charles A Narh
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Sandra A King
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Baldé S Mamadou
- Programme National de Lutte contre l'Onchocercose, le Trachome et les autres Maladies Tropicales Négligées, Ministère de la Santé Publique, Conakry, Guinea
| | - Lamia Diakité
- Programme National de Lutte contre l'Onchocercose, le Trachome et les autres Maladies Tropicales Négligées, Ministère de la Santé Publique, Conakry, Guinea
| | - Samuel K Dadzie
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Daniel A Boakye
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Jürg Utzinger
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Moses J Bockarie
- Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Benjamin G Koudou
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire. .,Unité de Formation et de Recherche Science de la Nature, Université Nangui Abrogoua, Abidjan, Côte d'Ivoire. .,Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, Liverpool, UK.
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Andrés M, Lorenz LM, Mbeleya E, Moore SJ. Modified mosquito landing boxes dispensing transfluthrin provide effective protection against Anopheles arabiensis mosquitoes under simulated outdoor conditions in a semi-field system. Malar J 2015; 14:255. [PMID: 26104719 PMCID: PMC4477292 DOI: 10.1186/s12936-015-0762-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/04/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Efforts to control malaria vectors have primarily focused on scaling-up of long-lasting insecticidal nets (LLINs) and indoor residual spraying. Although highly efficient against indoor-biting and indoor-resting vectors, these interventions have lower impact on outdoor-biting mosquitoes. Innovative vector control tools are required to prevent outdoor human-mosquito contacts. In this work, the potential of spatial repellents, delivered in an active system that requires minimal user compliance, to provide personal protection against exophagic mosquitoes active in the early evening was explored. METHODS A device previously used as an odour-baited lure and kill apparatus, the mosquito landing box (MLB), was modified to dispense the volatile synthetic pyrethroid, transfluthrin, as a spatial repellent. The MLB has an active odour-dispensing mechanism that uses a solar-powered fan and switches on at dusk to provide long duration dispensing of volatile compounds without the need for the user to remember to employ it. Two MLBs were located 5 m from a human volunteer to investigate the repellent effects of a transfluthrin 'bubble' created between the MLBs. Transfluthrin was emanated from polyester strips, hanging inside the MLB odour-dispensing unit. A fully randomized cross-over design was performed in a large, semi-field, screened cage to assess the effect of the repellent against laboratory-reared Anopheles arabiensis mosquitoes under ambient outdoor conditions. The knock-down capacity of the transfluthrin-treated strips was also evaluated at different time points up to 3 weeks after being impregnated to measure duration of efficacy. RESULTS The protective transfluthrin bubble provided 68.9% protection against An. arabiensis bites under these simulated outdoor conditions. Volatile transfluthrin caused low mortality among mosquitoes in the semi-field system. Transfluthrin-treated strips continued to knock down mosquitoes in laboratory tests, 3 weeks after impregnation, although this effect diminished with time. CONCLUSION Modified MLBs can be used as efficient and long-lasting dispensers of volatile spatial repellents such as transfluthrin, thereby providing high levels of protection against outdoor-biting mosquitoes in the peri-domestic space. They have a potential role in combatting outdoor malaria transmission without interfering with effective indoor interventions such as LLINs.
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Affiliation(s)
- Marta Andrés
- Department of Cellular Neurobiology, University of Göttingen, Julia-Lermontowa-Weg 3, 37077, Göttingen, Germany. .,London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | - Lena M Lorenz
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. .,Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Bagamoyo Research and Training Centre, Bagamoyo, Tanzania.
| | - Edgar Mbeleya
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Bagamoyo Research and Training Centre, Bagamoyo, Tanzania.
| | - Sarah J Moore
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Bagamoyo Research and Training Centre, Bagamoyo, Tanzania. .,Swiss Tropical and Public Health Institute, Socinstr. 57, 4051, Basel, Switzerland. .,University of Basel, Petersplatz 1, 4003, Basel, Switzerland.
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Govella NJ, Ogoma SB, Paliga J, Chaki PP, Killeen G. Impregnating hessian strips with the volatile pyrethroid transfluthrin prevents outdoor exposure to vectors of malaria and lymphatic filariasis in urban Dar es Salaam, Tanzania. Parasit Vectors 2015; 8:322. [PMID: 26063216 PMCID: PMC4465323 DOI: 10.1186/s13071-015-0937-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 06/03/2015] [Indexed: 11/30/2022] Open
Abstract
Background Semi-field trials using laboratory-reared Anopheles arabiensis have shown that, delivering the volatile pyrethroid transfluthrin by absorption into hessian strips, consistently provided > 99 % human protective efficacy against bites for 6 months without retreating. Here the impact of this approach upon human exposure to wild populations of vectors for both malaria and filariasis under full field conditions is assessed for the first time. Methods Transfluthrin-treated and untreated strips were placed around human volunteers conducting human landing catch in an outdoor environment in urban Dar es Salaam, where much human exposure to malaria and filariasis transmission occurs outdoors. The experiment was replicated 9 times at 16 outdoor catching stations in 4 distinct locations over 72 working nights between May and August 2012. Results Overall, the treated hessian strips conferred 99 % protection against An. gambiae (1 bite versus 159) and 92 % protection against Culex spp. (1478 bites versus 18,602). No decline in efficacy over the course of the study could be detected for the very sparse populations of An. gambiae (P = 0.32) and only a slow efficacy decline was observed for Culex spp. (P < 0.001), with protection remaining satisfactory over 3 months after strip treatment. Diversion of mosquitoes to unprotected humans in nearby houses was neither detected for An. gambiae (P = 0.152) nor for Culex spp. (Relative rate, [95 % CI] = 1.03, [0.95, 1.11], P = 0.499). Conclusion While this study raises more questions than it answers, the presented evidence of high protection over long periods suggest this technology may have potential for preventing outdoor transmission of malaria, lymphatic filariasis and other vector-borne pathogens.
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Affiliation(s)
- Nicodem J Govella
- Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Coordination Office, P.O Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania.
| | - Sheila B Ogoma
- Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Coordination Office, P.O Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania. .,US Army Medical Research Unit Kenya-Walter Reed Project, P.O. Box 54, Kisumu, Kenya.
| | - John Paliga
- Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Coordination Office, P.O Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania.
| | - Prosper P Chaki
- Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Coordination Office, P.O Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania.
| | - Gerry Killeen
- Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Coordination Office, P.O Box 78373, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania. .,Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, United Kingdom.
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Jankowska MM, Stoler J, Ofiesh C, Rain D, Weeks JR. Agency, access, and Anopheles: neighborhood health perceptions and the implications for community health interventions in Accra, Ghana. Glob Health Action 2015; 8:26492. [PMID: 25997424 PMCID: PMC4440875 DOI: 10.3402/gha.v8.26492] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 03/30/2015] [Accepted: 03/31/2015] [Indexed: 12/02/2022] Open
Abstract
Background Social and environmental factors are increasingly recognized for their ability to influence health outcomes at both individual and neighborhood scales in the developing urban world. Yet issues of spatial heterogeneity in these complex environments may obscure unique elements of neighborhood life that may be protective or harmful to human health. Resident perceptions of neighborhood effects on health may help to fill gaps in our interpretation of household survey results and better inform how to plan and execute neighborhood-level health interventions. Objective We evaluate differences in housing and socioeconomic indicators and health, environment, and neighborhood perceptions derived from the analysis of a household survey and a series of focus groups in Accra, Ghana. We then explore how neighborhood perceptions can inform survey results and ultimately neighborhood-level health interventions. Design Eleven focus groups were conducted across a socioeconomically stratified sample of neighborhoods in Accra, Ghana. General inductive themes from the focus groups were analyzed in tandem with data collected in a 2009 household survey of 2,814 women. In-depth vignettes expand upon the three most salient emergent themes. Results Household and socioeconomic characteristics derived from the focus groups corroborated findings from the survey data. Focus group and survey results diverged for three complex health issues: malaria, health-care access, and sense of personal agency in promoting good health. Conclusion Three vignettes reflecting community views about malaria, health-care access, and sense of personal agency in promoting good health highlight the challenges facing community health interventions in Accra and exemplify how qualitatively derived neighborhood-level health effects can help shape health interventions.
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Affiliation(s)
- Marta M Jankowska
- Department of Family Medicine and Public Health, University of California San Diego, San Diego, CA, USA;
| | - Justin Stoler
- Department of Geography and Regional Studies, University of Miami, Coral Gables, FL, USA.,Department of Public Health Sciences, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Caetlin Ofiesh
- Department of Geography, The George Washington University, Washington, DC, USA
| | - David Rain
- Department of Geography, The George Washington University, Washington, DC, USA
| | - John R Weeks
- Department of Geography, San Diego State University, San Diego, CA, USA
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Efficacy of neem chippings for mosquito larval control under field conditions. BMC Ecol 2015; 15:8. [PMID: 25888120 PMCID: PMC4355977 DOI: 10.1186/s12898-015-0041-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 02/20/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND An in depth understanding of mosquito breeding biology and factors regulating population sizes is fundamental for vector population control. This paper presents results from a survey of mosquito breeding habitats and the efficacy of neem chippings as a potential larvicide that can be integrated in mosquito control on Nyabondo Plateau in western Kenya. RESULTS Six main mosquito habitat types namely artificial ponds, abandoned fish ponds, active fish ponds, open drains, temporary pools and swamps were found in Nyabondo. Early anopheline instars were mainly recovered from temporary pools, artificial ponds and abandoned fish ponds. The mosquitoes collected were Anopheles gambiae sensu lato (35%), An. coustani (46%) and Culex spp (19%). Both early and late instar larvae of anopheline and culicine mosquitoes were more abundant in the controls than in the Bti and neem treated habitats. Within treated habitats, early instar anopheline mosquitoes were recovered more from habitats provided with neem and fish compared to Bti treated habitats. All treated habitats recorded higher numbers of early instar larvae than late instars or pupae, indicating that gravid female mosquitoes still oviposited within treated habitats. CONCLUSIONS Neem chippings are a good tool for mosquito larval source management under field conditions. However, more research needs to be done to quantify the contribution of this tool to the overall mosquito borne disease transmission.
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Maheu-Giroux M, Castro MC. Cost-effectiveness of larviciding for urban malaria control in Tanzania. Malar J 2014; 13:477. [PMID: 25476586 PMCID: PMC4289051 DOI: 10.1186/1475-2875-13-477] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 11/29/2014] [Indexed: 11/12/2022] Open
Abstract
Background Larviciding for malaria control can contribute to an Integrated Vector Management (IVM) approach. This intervention is currently supported in settings where breeding habitats are ‘few, fixed, and findable’, such as urban areas of sub-Saharan Africa, but the knowledge base regarding the cost-effectiveness of larviciding is non-existent. Methods Programme costs and effectiveness data were collected from the Dar es Salaam Urban Malaria Control Programme in Tanzania. Cost-effectiveness ratios (CER) were estimated from the provider and societal perspectives for standard indicators using different malaria transmission scenarios. Results CER for microbial larviciding were highly dependent on the assumed baseline malaria incidence rates. Using the societal perspective, net CER were estimated (in 2012 US dollars) at $43 (95% uncertainty intervals [UI]: $15-181) per disability-adjusted life year averted (DALY) when malaria incidence was 902 infections per 1,000 individuals, increasing to $545 (95% UI: $337-1,558) per DALY at an incidence of 122 per 1,000. Larviciding was shown to be cost-effective in Tanzania for incidences as low as 40 infections per 1,000 people per year. Conclusion This is believed to be the first study to estimate the cost-effectiveness of larviciding for urban malaria control in sub-Saharan Africa. The results support the use of larviciding as a cost-effective intervention in urban areas and managers of national malaria control programme should consider this intervention as part of an IVM approach. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-477) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Marcia C Castro
- Department of Global Health & Population, Harvard School of Public Health, Boston, MA, USA.
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Lawson AB, Carroll R, Castro M. Joint spatial Bayesian modeling for studies combining longitudinal and cross-sectional data. Stat Methods Med Res 2014; 23:611-24. [PMID: 24713159 PMCID: PMC5388557 DOI: 10.1177/0962280214527383] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Design for intervention studies may combine longitudinal data collected from sampled locations over several survey rounds and cross-sectional data from other locations in the study area. In this case, modeling the impact of the intervention requires an approach that can accommodate both types of data, accounting for the dependence between individuals followed up over time. Inadequate modeling can mask intervention effects, with serious implications for policy making. In this paper we use data from a large-scale larviciding intervention for malaria control implemented in Dar es Salaam, United Republic of Tanzania, collected over a period of almost 5 years. We apply a longitudinal Bayesian spatial model to the Dar es Salaam data, combining follow-up and cross-sectional data, treating the correlation in longitudinal observations separately, and controlling for potential confounders. An innovative feature of this modeling is the use of Ornstein-Uhlenbeck process to model random time effects. We contrast the results with other Bayesian modeling formulations, including cross-sectional approaches that consider individual-level random effects to account for subjects followed up in two or more surveys. The longitudinal modeling approach indicates that the intervention significantly reduced the prevalence of malaria infection in Dar es Salaam by 20% whereas the joint model did not suggest significance within the results. Our results suggest that the longitudinal model is to be preferred when longitudinal information is available at the individual level.
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Affiliation(s)
- Andrew B Lawson
- Department of Public Health, Medical University of South Carolina, Charleston, USA
| | - Rachel Carroll
- Department of Public Health, Medical University of South Carolina, Charleston, USA
| | - Marcia Castro
- Department of Global Health and Population, Harvard School of Public Health, Boston, USA
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Chaki PP, Kannady K, Mtasiwa D, Tanner M, Mshinda H, Kelly AH, Killeen GF. Institutional evolution of a community-based programme for malaria control through larval source management in Dar es Salaam, United Republic of Tanzania. Malar J 2014; 13:245. [PMID: 24964790 PMCID: PMC4082415 DOI: 10.1186/1475-2875-13-245] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 06/01/2014] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Community-based service delivery is vital to the effectiveness, affordability and sustainability of vector control generally, and to labour-intensive larval source management (LSM) programmes in particular. CASE DESCRIPTION The institutional evolution of a city-level, community-based LSM programme over 14 years in urban Dar es Salaam, Tanzania, illustrates how operational research projects can contribute to public health governance and to the establishment of sustainable service delivery programmes. Implementation, management and governance of this LSM programme is framed within a nested set of spatially-defined relationships between mosquitoes, residents, government and research institutions that build upward from neighbourhood to city and national scales. DISCUSSION AND EVALUATION The clear hierarchical structure associated with vertical, centralized management of decentralized, community-based service delivery, as well as increasingly clear differentiation of partner roles and responsibilities across several spatial scales, contributed to the evolution and subsequent growth of the programme. CONCLUSIONS The UMCP was based on the principle of an integrated operational research project that evolved over time as the City Council gradually took more responsibility for management. The central role of Dar es Salaam's City Council in coordinating LSM implementation enabled that flexibility; the institutionalization of management and planning in local administrative structures enhanced community-mobilization and funding possibilities at national and international levels. Ultimately, the high degree of program ownership by the City Council and three municipalities, coupled with catalytic donor funding and technical support from expert overseas partners have enabled establishment of a sustainable, internally-funded programme implemented by the National Ministry of Health and Social Welfare and supported by national research and training institutes.
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Affiliation(s)
- Prosper P Chaki
- Ifakara Health Institute, Environmental Health and Ecological Sciences Thematic Group, Kiko Avenue, Mikocheni, PO Box 78373, Dar es Salaam, United Republic of Tanzania.
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Herrera-Varela M, Lindh J, Lindsay SW, Fillinger U. Habitat discrimination by gravid Anopheles gambiae sensu lato--a push-pull system. Malar J 2014; 13:133. [PMID: 24693951 PMCID: PMC3975139 DOI: 10.1186/1475-2875-13-133] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 03/27/2014] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND The non-random distribution of anopheline larvae in natural habitats suggests that gravid females discriminate between habitats of different quality. Whilst physical and chemical cues used by Culex and Aedes vector mosquitoes for selecting an oviposition site have been extensively studied, those for Anopheles remain poorly explored. Here the habitat selection by Anopheles gambiae sensu lato (s.l.), the principal African malaria vector, was investigated when presented with a choice of two infusions made from rabbit food pellets, or soil. METHODS Natural colonization and larval survival was evaluated in artificial ponds filled randomly with either infusion. Dual-choice, egg-count bioassays evaluated the responses of caged gravid females to (1) two- to six-day old infusions versus lake water; (2) autoclaved versus non-autoclaved soil infusions; and assessed (3) the olfactory memory of gravid females conditioned in pellet infusion as larvae. RESULTS Wild Anopheles exclusively colonized ponds with soil infusion and avoided those with pellet infusion. When the individual infusions were tested in comparison with lake water, caged An. gambiae sensu stricto (s.s.) showed a dose response: females increasingly avoided the pellet infusion with increasing infusion age (six-day versus lake water: odds ratio (OR) 0.22; 95% confidence interval (CI) 0.1-0.5) and showed increasing preference to lay eggs as soil infusion age increased (six-day versus lake water: OR 2.1; 95% CI 1.4-3.3). Larvae survived in soil infusions equally well as in lake water but died in pellet infusions. Anopheles gambiae s.s. preferred to lay eggs in the non-autoclaved soil (OR 2.6; 95% CI 1.8-3.7) compared with autoclaved soil. There was no change in the avoidance of pellet infusion by individuals reared in the infusion compared with those reared in lake water. CONCLUSION Wild and caged An. gambiae s.l. females discriminate between potential aquatic habitats for oviposition. These choices benefit the survival of the offspring. Although the study was not designed to distinguish between stimuli that acted over a distance or on contact, it could be demonstrated that the choice of habitat is mediated by chemical cues based on both preference and avoidance. These cues, if identified, might be developed for 'push-pull' strategies to improve malaria vector monitoring and control.
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Affiliation(s)
- Manuela Herrera-Varela
- Department of Diseases Control, London School of Hygiene and Tropical Medicine, London, UK
- International Centre for Insect Physiology and Ecology (icipe)-Thomas Odhiambo Campus, Mbita, Kenya
| | - Jenny Lindh
- Royal Institute of Technology, Stockholm, Sweden
| | - Steven W Lindsay
- School of Biological and Biomedical Sciences, Durham University, Durham, UK
| | - Ulrike Fillinger
- Department of Diseases Control, London School of Hygiene and Tropical Medicine, London, UK
- International Centre for Insect Physiology and Ecology (icipe)-Thomas Odhiambo Campus, Mbita, Kenya
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Mereta ST, Yewhalaw D, Boets P, Ahmed A, Duchateau L, Speybroeck N, Vanwambeke SO, Legesse W, De Meester L, Goethals PLM. Physico-chemical and biological characterization of anopheline mosquito larval habitats (Diptera: Culicidae): implications for malaria control. Parasit Vectors 2013; 6:320. [PMID: 24499518 PMCID: PMC4029358 DOI: 10.1186/1756-3305-6-320] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 10/25/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A fundamental understanding of the spatial distribution and ecology of mosquito larvae is essential for effective vector control intervention strategies. In this study, data-driven decision tree models, generalized linear models and ordination analysis were used to identify the most important biotic and abiotic factors that affect the occurrence and abundance of mosquito larvae in Southwest Ethiopia. METHODS In total, 220 samples were taken at 180 sampling locations during the years 2010 and 2012. Sampling sites were characterized based on physical, chemical and biological attributes. The predictive performance of decision tree models was evaluated based on correctly classified instances (CCI), Cohen's kappa statistic (κ) and the determination coefficient (R2). A conditional analysis was performed on the regression tree models to test the relation between key environmental and biological parameters and the abundance of mosquito larvae. RESULTS The decision tree model developed for anopheline larvae showed a good model performance (CCI = 84 ± 2%, and κ = 0.66 ± 0.04), indicating that the genus has clear habitat requirements. Anopheline mosquito larvae showed a widespread distribution and especially occurred in small human-made aquatic habitats. Water temperature, canopy cover, emergent vegetation cover, and presence of predators and competitors were found to be the main variables determining the abundance and distribution of anopheline larvae. In contrast, anopheline mosquito larvae were found to be less prominently present in permanent larval habitats. This could be attributed to the high abundance and diversity of natural predators and competitors suppressing the mosquito population densities. CONCLUSIONS The findings of this study suggest that targeting smaller human-made aquatic habitats could result in effective larval control of anopheline mosquitoes in the study area. Controlling the occurrence of mosquito larvae via drainage of permanent wetlands may not be a good management strategy as it negatively affects the occurrence and abundance of mosquito predators and competitors and promotes an increase in anopheline population densities.
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Affiliation(s)
| | | | - Pieter Boets
- Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J, Plateaustraat 22, B-9000 Ghent, Belgium.
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Mwakitalu ME, Malecela MN, Pedersen EM, Mosha FW, Simonsen PE. Urban lymphatic filariasis in the metropolis of Dar es Salaam, Tanzania. Parasit Vectors 2013; 6:286. [PMID: 24289718 PMCID: PMC3849855 DOI: 10.1186/1756-3305-6-286] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 09/19/2013] [Indexed: 12/16/2022] Open
Abstract
Background The last decades have seen a considerable increase in urbanization in Sub-Saharan Africa, and it is estimated that over 50% of the population will live in urban areas by 2040. Rapid growth of cities combined with limited economic resources often result in informal settlements and slums with favorable conditions for proliferation of vectors of lymphatic filariasis (LF). In Dar es Salaam, which has grown more than 30 times in population during the past 55 years (4.4 million inhabitants in 2012), previous surveys have indicated high prevalences of LF. This study investigated epidemiological aspects of LF in Dar es Salaam, as a background for planning and implementation of control. Methods Six sites with varying distance from the city center (3–30 km) and covering different population densities, socioeconomic characteristics, and water, sewerage and sanitary facilities were selected for the study. Pupils from one public primary school at each site were screened for circulating filarial antigen (CFA; marker of adult worm infection) and antibodies to Bm14 (marker of exposure to transmission). Community members were examined for CFA, microfilariae and chronic manifestations. Structured questionnaires were administered to pupils and heads of community households, and vector surveys were carried out in selected households. Results The study indicated that a tremendous decrease in the burden of LF infection had occurred, despite haphazard urbanisation. Contributing factors may be urban malaria control targeting Anopheles vectors, short survival time of the numerous Culex quinquefasciatus vectors in the urban environment, widespread use of bed nets and other mosquito proofing measures, and mass drug administration (MDA) in 2006 and 2007. Although the level of ongoing transmission was low, the burden of chronic LF disease was still high. Conclusions The development has so far been promising, but continued efforts are necessary to ensure elimination of LF as a public health problem. These will include improving the awareness of people about the role of mosquitoes in transmission of LF, more thorough implementation of environmental sanitation to reduce Cx. quinquefasciatus breeding, continued MDA to high-risk areas, and set-up of programmes for management of chronic LF disease.
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Affiliation(s)
| | | | | | | | - Paul E Simonsen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Thorvaldsensvej 57, 1871 Frederiksberg C, Denmark.
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Maheu-Giroux M, Castro MC. Impact of community-based larviciding on the prevalence of malaria infection in Dar es Salaam, Tanzania. PLoS One 2013; 8:e71638. [PMID: 23977099 PMCID: PMC3743749 DOI: 10.1371/journal.pone.0071638] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 07/01/2013] [Indexed: 12/18/2022] Open
Abstract
Background The use of larval source management is not prioritized by contemporary malaria control programs in sub-Saharan Africa despite historical success. Larviciding, in particular, could be effective in urban areas where transmission is focal and accessibility to Anopheles breeding habitats is generally easier than in rural settings. The objective of this study is to assess the effectiveness of a community-based microbial larviciding intervention to reduce the prevalence of malaria infection in Dar es Salaam, United Republic of Tanzania. Methods and Findings Larviciding was implemented in 3 out of 15 targeted wards of Dar es Salaam in 2006 after two years of baseline data collection. This intervention was subsequently scaled up to 9 wards a year later, and to all 15 targeted wards in 2008. Continuous randomized cluster sampling of malaria prevalence and socio-demographic characteristics was carried out during 6 survey rounds (2004–2008), which included both cross-sectional and longitudinal data (N = 64,537). Bayesian random effects logistic regression models were used to quantify the effect of the intervention on malaria prevalence at the individual level. Effect size estimates suggest a significant protective effect of the larviciding intervention. After adjustment for confounders, the odds of individuals living in areas treated with larviciding being infected with malaria were 21% lower (Odds Ratio = 0.79; 95% Credible Intervals: 0.66–0.93) than those who lived in areas not treated. The larviciding intervention was most effective during dry seasons and had synergistic effects with other protective measures such as use of insecticide-treated bed nets and house proofing (i.e., complete ceiling or window screens). Conclusion A large-scale community-based larviciding intervention significantly reduced the prevalence of malaria infection in urban Dar es Salaam.
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Affiliation(s)
- Mathieu Maheu-Giroux
- Department of Global Health and Population, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Marcia C. Castro
- Department of Global Health and Population, Harvard School of Public Health, Boston, Massachusetts, United States of America
- * E-mail:
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Munga S, Vulule J, Kweka EJ. Response of Anopheles gambiae s.l. (Diptera: Culicidae) to larval habitat age in western Kenya highlands. Parasit Vectors 2013; 6:13. [PMID: 23324330 PMCID: PMC3564891 DOI: 10.1186/1756-3305-6-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 01/09/2013] [Indexed: 11/10/2022] Open
Abstract
Background Larval control is of paramount importance in the reduction of vector populations. Previous observations have suggested that, larvae of Anopheles gambiae s.l occur more often in small temporary habitats while other studies showed that long-lasting stable habitats are more productive than unstable habitats. In addition, the physical and biological conditions and stability of larval habitats can change rapidly in natural conditions. Therefore, we examined the effect of larval habitat age on productivity, larval survival and oviposition preference of Anopheles gambiae. Methods We sampled the three different habitat ages (10, 20 and 30 days) on a daily basis for a period of six months to determine mosquito larval abundance. In addition, we tested the effect of age of water (habitat age) on the oviposition choice preference of An. gambiae, larval development time and survivorship, and wing lengths of emerging adults. Additionally, chlorophyll a and abundance of mosquito larval predators in these habitats were monitored. Results Anopheles gambiae s.l. larvae were significantly more abundant (P=0.0002) in habitats that were cleared every 10 days compared to the other habitats. In particular, there were 1.7 times more larvae in this habitat age compared to the ones that were cleared every 30 days. There were significantly (P<0.001) more mosquito larval predators in the ‘30 day’ habitats compared to the other habitats. Oviposition experiments revealed that significantly more eggs (P<0.05) were laid in fresh water and water that was 5 days old compared to water that was 10 and 15 days old. However, pupation rate, development times and wing lengths of male and female An. gambiae in the different habitat ages was statistically insignificant (P>0.05). Conclusion The current study confirmed that age of the habitat significantly influences the productivity of malaria vectors in western Kenya highlands. Given that malaria vectors were found in all habitats with varying ages of water, simple environmental methods of maintaining the drainage ditches in the valley bottoms can help reduce larval abundance of malaria vectors. Such inexpensive methods of controlling mosquito breeding could be promoted to supplement other vector control methods, especially in areas where scarce resources are available for intensive mosquito control.
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Affiliation(s)
- Stephen Munga
- Centre for Global Health Research, Kenya Medical Research Institute, Nairobi, Kenya
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Abstract
Lymphatic filariasis (LF) is a disabling and disfiguring disease resulting from a mosquito-borne parasitic infection. It is a major public health problem in many countries with a warm climate. Research and control activities have mainly focused on LF in rural areas where it also has its major impact. However, with rapid and unplanned growth of cities in the developing world, there is a need also to consider LF transmission and control in urban settings. Here, we review currently available knowledge on urban LF and the environmental and socio-economic basis for its occurrence. Among the three parasite species causing LF in humans, only Wuchereria bancrofti has been documented to have a significant potential for urban transmission. This is primarily because one of its vectors, Culex quinquefasciatus, thrives and proliferates excessively in crowded city areas with poor sanitary, sewerage and drainage facilities. For this reason, urban LF also often shows a marked focality in distribution, with most cases clustered in areas inhabited by the less privileged city populations. More knowledge on urban LF is needed, in particular on its socio-economic and human behavioural context, on the potential for transmission in regions where other LF vector species predominate, and on rapid methods for identification and mapping of risk areas, to provide a strong evidence base for its control.
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Affiliation(s)
- Paul E. Simonsen
- DBL–Centre for Health Research and Development, Faculty of Health and Medical Sciences, University of Copenhagen, Thorvaldsensvej 57, 1871 Frederiksberg C, Denmark
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Factors contributing to urban malaria transmission in sub-saharan Africa: a systematic review. J Trop Med 2012; 2012:819563. [PMID: 23125863 PMCID: PMC3483782 DOI: 10.1155/2012/819563] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/17/2012] [Accepted: 09/17/2012] [Indexed: 12/04/2022] Open
Abstract
Sub-Saharan Africa suffers by far the greatest malaria burden worldwide and is currently undergoing a profound demographic change, with a growing proportion of its population moving to urban areas. Urbanisation is generally expected to reduce malaria transmission; however the disease still persists in African cities, in some cases at higher levels than in nearby rural areas. Objective. This paper aims to collate and analyse risk factors for urban malaria transmission throughout sub-Saharan Africa and to discuss their implications for control. Methods. A systematic search on malaria and urbanisation was carried out focusing on sub-Saharan Africa. Particular interest was taken in vector breeding sites in urban and periurban areas. Results. A variety of urban vector breeding sites were catalogued, the majority of which were artificial, including urban agriculture, tyre tracks, and ditches. Natural breeding sites varied according to location. Low socioeconomic status was a significant risk factor for malaria, often present in peri-urban areas. A worrying trend was seen in the adaptation of malaria vector species to the urban environment. Urban malaria is highly focused and control programs should reflect this. Conclusion. As urbanisation continues and vector species adapt, continued monitoring and control of urban malaria in sub-Saharan Africa is essential.
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Govella NJ, Ferguson H. Why Use of Interventions Targeting Outdoor Biting Mosquitoes will be Necessary to Achieve Malaria Elimination. Front Physiol 2012; 3:199. [PMID: 22701435 PMCID: PMC3372949 DOI: 10.3389/fphys.2012.00199] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 05/22/2012] [Indexed: 12/22/2022] Open
Affiliation(s)
- Nicodem James Govella
- Biomedical and Environmental Thematic Group, Ifakara Health InstituteDar es Salaam, United Republic of Tanzania
| | - Heather Ferguson
- College of Medical, Veterinary and Life Sciences, Boyd Orr Centre for Population and Ecosystem Health, University of GlasgowGlasgow, UK
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Imbahale SS, Githeko A, Mukabana WR, Takken W. Integrated mosquito larval source management reduces larval numbers in two highland villages in western Kenya. BMC Public Health 2012; 12:362. [PMID: 22607227 PMCID: PMC3433356 DOI: 10.1186/1471-2458-12-362] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 05/18/2012] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND In western Kenya, malaria remains one of the major health problems and its control remains an important public health measure. Malaria control is by either use of drugs to treat patients infected with malaria parasites or by controlling the vectors. Vector control may target the free living adult or aquatic (larval) stages of mosquito. The most commonly applied control strategies target indoor resting mosquitoes. However, because mosquitoes spend a considerable time in water, targeting the aquatic stages can complement well with existing adult control measures. METHODS Larval source management (LSM) of malaria vectors was examined in two villages i.e. Fort Ternan and Lunyerere, with the aim of testing strategies that can easily be accessed by the affected communities. Intervention strategies applied include environmental management through source reduction (drainage of canals, land levelling or by filling ditches with soil), habitat manipulation (by provision of shading from arrow root plant), application of Bacillus thuringiensis var israelensis (Bti) and the use of predatory fish, Gambusia affinis. The abundance of immature stages of Anopheles and Culex within intervention habitats was compared to that within non-intervention habitats. RESULTS The findings show that in Fort Ternan no significant differences were observed in the abundance of Anopheles early and late instars between intervention and non-intervention habitats. In Lunyerere, the abundance of Anopheles early instars was fifty five times more likely to be present within non-intervention habitats than in habitats under drainage. No differences in early instars abundance were observed between non-intervention and habitats applied with Bti. However, late instars had 89 % and 91 % chance of being sampled from non-intervention rather than habitats under drainage and those applied with Bti respectively. CONCLUSION Most of these interventions were applied in habitats that arose due to human activities. Involvement of community members in control programs would be beneficial in the long term once they understand the role they play in malaria transmission. Apart from the need for communities to be educated on their role in malaria transmission, there is a need to develop and test strategies that can easily be accessed and hence be used by the affected communities. The proposed LSM strategies target outdoor immature mosquitoes and hence can complement well with control measures that target indoor resting vectors. Therefore inclusion of LSM in Integrated Vector Management (IVM) program would be beneficial.
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Affiliation(s)
- Susan S Imbahale
- Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands
- Kenya Medical Research Institute, Centre for Global Health Research, P.O Box 1578-40100, Kisumu, Kenya
- School of Pure and Applied Sciences, Kenya Polytechnic University College, P.O Box 52428-00200, Nairobi, Kenya
| | - Andrew Githeko
- Kenya Medical Research Institute, Centre for Global Health Research, P.O Box 1578-40100, Kisumu, Kenya
| | - Wolfgang R Mukabana
- International Centre of Insect Physiology and Ecology, P.O. Box 30772 – 00100 GPO, Nairobi, Kenya
- School of Biological Sciences, University of Nairobi, P.O. Box 30197-00100 GPO, Nairobi, Kenya
| | - Willem Takken
- Laboratory of Entomology, Wageningen University, P.O. Box 8031, 6700 EH, Wageningen, The Netherlands
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Chandy A, Thakur AS, Singh MP, Manigauha A. A review of neglected tropical diseases: filariasis. ASIAN PAC J TROP MED 2012; 4:581-6. [PMID: 21803313 DOI: 10.1016/s1995-7645(11)60150-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 04/11/2011] [Accepted: 06/15/2011] [Indexed: 10/17/2022] Open
Abstract
Filariasis is result of parasitic infection caused by three specific kinds of round worm. Lymphatic filariasis is found in under developed region of South America, Central Africa, pacific and Caribbian. It has been found for centuries, with main symptoms as elephant like swelling of the arms, legs and genitals. It is estimate that 120 millions peoples in the world have lymphatic filariasis. The spread of diseases and the challenge encountered in its management are discussed along with a review on drugs against filariasis in this article. Detail on clinical effect of drugs on the infection, safety profile, status in clinical practices and drug resistances are also covered.
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Affiliation(s)
- Anish Chandy
- School of Pharmacy, Chouksey Engineering College, Bilaspur, Chattishgarh, India.
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Paramanik M, Bhattacharjee I, Chandra G. Studies on breeding habitats and density of postembryonic immature filarial vector in a filarial endemic area. Asian Pac J Trop Biomed 2012. [DOI: 10.1016/s2221-1691(12)60511-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Fillinger U, Lindsay SW. Larval source management for malaria control in Africa: myths and reality. Malar J 2011; 10:353. [PMID: 22166144 PMCID: PMC3273449 DOI: 10.1186/1475-2875-10-353] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 12/13/2011] [Indexed: 08/15/2023] Open
Abstract
As malaria declines in many African countries there is a growing realization that new interventions need to be added to the front-line vector control tools of long-lasting impregnated nets (LLINs) and indoor residual spraying (IRS) that target adult mosquitoes indoors. Larval source management (LSM) provides the dual benefits of not only reducing numbers of house-entering mosquitoes, but, importantly, also those that bite outdoors. Large-scale LSM was a highly effective method of malaria control in the first half of the twentieth century, but was largely disbanded in favour of IRS with DDT. Today LSM continues to be used in large-scale mosquito abatement programmes in North America and Europe, but has only recently been tested in a few trials of malaria control in contemporary Africa. The results from these trials show that hand-application of larvicides can reduce transmission by 70-90% in settings where mosquito larval habitats are defined but is largely ineffectual where habitats are so extensive that not all of them can be covered on foot, such as areas that experience substantial flooding. Importantly recent evidence shows that LSM can be an effective method of malaria control, especially when combined with LLINs. Nevertheless, there are a number of misconceptions or even myths that hamper the advocacy for LSM by leading international institutions and the uptake of LSM by Malaria Control Programmes. Many argue that LSM is not feasible in Africa due to the high number of small and temporary larval habitats for Anopheles gambiae that are difficult to find and treat promptly. Reference is often made to the Ross-Macdonald model to reinforce the view that larval control is ineffective. This paper challenges the notion that LSM cannot be successfully used for malaria control in African transmission settings by highlighting historical and recent successes, discussing its potential in an integrated vector management approach working towards malaria elimination and critically reviewing the most common arguments that are used against the adoption of LSM.
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Affiliation(s)
- Ulrike Fillinger
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
- International Centre of Insect Physiology and Ecology, Thomas Odhiambo Campus, Mbita, Mbita 40305, Kenya
| | - Steven W Lindsay
- Department of Disease Control, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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