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Onen H, Kaddumukasa MA, Kayondo JK, Akol AM, Tripet F. A review of applications and limitations of using aquatic macroinvertebrate predators for biocontrol of the African malaria mosquito, Anopheles gambiae sensu lato. Parasit Vectors 2024; 17:257. [PMID: 38867296 PMCID: PMC11170859 DOI: 10.1186/s13071-024-06332-3] [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: 03/18/2024] [Accepted: 05/25/2024] [Indexed: 06/14/2024] Open
Abstract
Macroinvertebrate predators such as backswimmers (Heteroptera: Notonectidae), dragonflies (Odonata: Aeshnidae), and predatory diving beetles (Coleoptera: Dytiscidae) naturally inhabit aquatic ecosystems. Some aquatic ecosystems inhabited by these macroinvertebrate predator taxa equally form malaria vector larval habitats. The presence of these predators in malaria vector larval habitats can negatively impact on development, adult body size, fecundity, and longevity of the malaria vectors, which form important determinants of their fitness and future vectorial capacity. These potential negative impacts caused by aquatic macroinvertebrate predators on malaria vectors warrant their consideration as biocontrol agents in an integrated program to combat malaria. However, the use of these macroinvertebrate predators in malaria biocontrol is currently constrained by technical bottlenecks linked to their generalist predatory tendencies and often long life cycles, demanding complex rearing systems. We reviewed the literature on the use of aquatic macroinvertebrate predators for biocontrol of malaria vectors from the An. gambiae s.l. complex. The available information from laboratory and semi-field studies has shown that aquatic macroinvertebrates have the potential to consume large numbers of mosquito larvae and could thus offer an additional approaches in integrated malaria vector management strategies. The growing number of semi-field structures available in East and West Africa provides an opportunity to conduct ecological experimental studies to reconsider the potential of using aquatic macroinvertebrate predators as a biocontrol tool. To achieve a more sustainable approach to controlling malaria vector populations, additional, non-chemical interventions could provide a more sustainable approach, in comparison with the failing chemical control tools, and should be urgently considered for integration with the current mosquito vector control campaigns.
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Affiliation(s)
- Hudson Onen
- Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, School of Biosciences, Makerere University, P.O Box 7062, Kampala, Uganda.
- Department of Entomology, Uganda Virus Research Institute (UVRI), P.O Box 49, Entebbe, Uganda.
- Department of Biological Sciences, Faculty of Science, Kyambogo University, P.O. Box 1, Kampala, Uganda.
| | - Martha A Kaddumukasa
- Department of Biological Sciences, Faculty of Science, Kyambogo University, P.O. Box 1, Kampala, Uganda
| | - Jonathan K Kayondo
- Department of Entomology, Uganda Virus Research Institute (UVRI), P.O Box 49, Entebbe, Uganda
| | - Anne M Akol
- Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, School of Biosciences, Makerere University, P.O Box 7062, Kampala, Uganda
| | - Frédéric Tripet
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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Pambit Zong CM, Coleman S, Mohammed AR, Owusu-Asenso CM, Akuamoah-Boateng Y, Sraku IK, Attah SK, Cui L, Afrane YA. Baseline susceptibility of Anopheles gambiae to clothianidin in northern Ghana. Malar J 2024; 23:12. [PMID: 38195484 PMCID: PMC10777513 DOI: 10.1186/s12936-023-04769-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 10/25/2023] [Indexed: 01/11/2024] Open
Abstract
BACKGROUND Clothianidin, an insecticide with a novel mode of action, has been deployed in the annual indoor residual spraying programme in northern Ghana since March 2021. To inform pragmatic management strategies and guide future studies, baseline data on local Anopheles gambiae sensu lato (s.l.) susceptibility to the clothianidin insecticide were collected in Kpalsogu, a village in the Northern region, Ghana. METHODS Phenotypic susceptibility of An. gambiae mosquitoes to clothianidin was assessed using the World Health Organization (WHO) insecticide resistance monitoring bioassay. The WHO cone bioassays were conducted on mud and cement walls sprayed with Sumishield 50 wettable granules (WG) (with clothianidin active ingredient). Daily mortalities were recorded for up to 7 days to observe for delayed mortalities. Polymerase chain reaction (PCR) technique was used to differentiate the sibling species of the An. gambiae complex and also for the detection of knock down resistance genes (kdr) and the insensitive acetylcholinesterase mutation (ace-1). RESULTS The WHO susceptibility bioassay revealed a delayed killing effect of clothianidin. Mosquitoes exposed to the cone bioassays for 5 min died 120 h after exposure. Slightly higher mortalities were observed in mosquitoes exposed to clothianidin-treated cement wall surfaces than mosquitoes exposed to mud wall surfaces. The kdr target-site mutation L1014F occurred at very high frequencies (0.89-0.94) across all vector species identified whereas the ace-1 mutation occurred at moderate levels (0.32-0.44). Anopheles gambiae sensu stricto was the most abundant species observed at 63%, whereas Anopheles arabiensis was the least observed at 9%. CONCLUSIONS Anopheles gambiae s.l. mosquitoes in northern Ghana were susceptible to clothianidin. They harboured kdr mutations at high frequencies. The ace-1 mutation occurred in moderation. The results of this study confirm that clothianidin is an effective active ingredient and should be utilized in malaria vector control interventions.
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Affiliation(s)
- Cosmos M Pambit Zong
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Sylvester Coleman
- Department of Clinical Microbiology, Department of Clinical Microbiology, College of Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Abdul Rahim Mohammed
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Christopher M Owusu-Asenso
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Yaw Akuamoah-Boateng
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Isaac K Sraku
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Simon K Attah
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Liwang Cui
- Department of Internal Medicine, University of South Florida, 3720 Spectrum Blvd, Tampa, FL, 33612, USA
| | - Yaw A Afrane
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana.
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Gichuki PM, Kibe L, Mwatele C, Mwangangi J, Mbogo CM. Towards an integrated vector management approach for sustainable control of schistosomiasis and malaria in Mwea, Kirinyaga County, Kenya: Baseline epidemiological and vector results. Heliyon 2023; 9:e20966. [PMID: 37876477 PMCID: PMC10590948 DOI: 10.1016/j.heliyon.2023.e20966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 10/12/2023] [Accepted: 10/12/2023] [Indexed: 10/26/2023] Open
Abstract
Background Vector control is an important approach in the control of most parasitic and vector-borne diseases including malaria, and schistosomiasis. Distribution of these two infections often overlaps and in such areas it's more economically viable to employ an integrated approach in the control of their vectors which largely shares the same breeding ecosystem. We carried out a baseline epidemiological and vector surveys for malaria and schistosomiasis in Mwea, Kirinyaga County, in preparation for the upscaling of integrated vector management (IVM) for the two diseases. Methods This was a repeated cross sectional survey, where mosquito and snails were sampled during dry and wet seasons in three different ecological zones, Kiamaciri, Thiba and Murinduko to identify possible breeding sites. Mosquito larvae were collected using standard dippers, adults using CDC miniature light traps while snail vectors were sampled using standard snail scoops in different breeding habitats. A total of 1200 pupils from 12 primary schools were tested for malaria using rapid diagnostic tests (Malaria Pf/PAN Ag combo). Stool samples were processed using the Kato Katz technique for intestinal schistosomiasis. Results The overall prevalence of intestinal schistosomiasis was 9.08 % (95 % CI: 07.00-11.00), with Kiamaciri zone recording the highest prevalence at 19 % (95%CI: 15.00-23.00) and Murinduko zone the least at 0.17 % (95%CI: 0.00-0.01). Majority of the infections were of light intensity 78.9 % (95%CI: 70.04-86.13). There was no positive malaria case detected in this study. Of the 3208 adult mosquitoes sampled during the dry season, 20.6 % (95 % CI: 19.25-22.08) were Anopheles gambiae s.l while 79.4 % (95 % CI: 77.92-80.75) were culicines. During the wet season, 3378 adult mosquitoes were collected, of which 14.7 % (95 % CI: 13.56-15.98) were Anopheles gambiae s.l and 85.3 % (95 % CI: 84.02-86.44) culicines. Overall, 4085 mosquito larvae were collected during the two seasons, of which, 57.3 % and 42.7 % were anopheles and culicine respectively. Majority of the larvae (85.1 % (95%CI: 84.01-86.10) were collected during the wet season, with only 14.9 % (95%CI: 14.10-16.00) being collected during the dry season. A total of 2292 fresh water vector snails were collected with a majority (69.6 % (95%CI: 68.00-71.10) being Biomphalaria pffeiferi responsible for transmission of intestinal schistosomiasis. Conclusion This study demonstrates that intestinal schistosomiasis is prevalent in Kiamaciri and Thiba zones, and points to the possibility of active transmission of schistosomiasis in Murinduko zone. Malaria vectors were predominantly observed in all sites despite there being no malaria positive case. Culex quinquefaciatus responsible for the spread of several arboviruses was also observed. The presence of these vectors may lead to future disease outbreaks in the area if concerted control initiatives are not undertaken. The disease vectors shared the same breeding sites and thus its economical and feasible to adopt an integrated vector management approach in control efforts for these disease in the study area.
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Affiliation(s)
- Paul M. Gichuki
- Kenya Medical Research Institute (KEMRI), Eastern & Southern Africa Centre of International Parasite Control (ESACIPAC), Nairobi, P.O BOX 54840-00200 Nairobi, Kenya
- School of Health Sciences, Meru University of Science and Technology, P.O BOX 972-60200 Meru, Kenya
| | - Lydia Kibe
- Kenya Medical Research Institute (KEMRI), Eastern & Southern Africa Centre of International Parasite Control (ESACIPAC), Nairobi, P.O BOX 54840-00200 Nairobi, Kenya
| | - Cassian Mwatele
- Kenya Medical Research Institute (KEMRI), Eastern & Southern Africa Centre of International Parasite Control (ESACIPAC), Nairobi, P.O BOX 54840-00200 Nairobi, Kenya
| | - Joseph Mwangangi
- KEMRI-Wellcome Trust Research Programme, Public Health Unit, PO Box 43640 - 00100, Nairobi, Kenya
- Kenya Medical Research Institute (KEMRI), Centre for Geographical Medicine Research-Coast (CGMR-C). P.O Box 230- 80108 Kilifi, Kenya
| | - Charles M. Mbogo
- Kenya Medical Research Institute (KEMRI), Eastern & Southern Africa Centre of International Parasite Control (ESACIPAC), Nairobi, P.O BOX 54840-00200 Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Public Health Unit, PO Box 43640 - 00100, Nairobi, Kenya
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Forson AO, Hinne IA, Sraku IK, Afrane YA. Larval habitat stability and productivity in two sites in Southern Ghana. Malar J 2023; 22:74. [PMID: 36864430 PMCID: PMC9983185 DOI: 10.1186/s12936-023-04498-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 02/14/2023] [Indexed: 03/04/2023] Open
Abstract
BACKGROUND Mosquito larval source management (LSM) is a valuable additional tool for malaria vector control. Understanding the characteristics of mosquito larval habitats and its ecology in different land use types can give valuable insight for an effective larval control strategy. This study determined the stability and productivity of potential anopheline larval habitats in two different ecological sites: Anyakpor and Dodowa in southern Ghana. METHODS A total of 59 aquatic habitats positive for anopheline larvae were identified, and sampled every two weeks for a period of 30 weeks using a standard dipping method. Larvae were collected using standard dippers and were raised in the insectary for identification. Sibling species of the Anopheles gambiae sensu lato (s.l.) were further identified by polymerase chain reaction. The presence of larval habitats, their stability and larvae positive habitats were compared between the two sites using Mann-Whitney U and the Kruskal-Wallis test. Factors affecting the presence of An. gambiae larvae and physicochemical properties at the sites were determined using multiple logistic regression analysis and Spearman's correlation. RESULTS Out of a total of 13,681 mosquito immatures collected, 22.6% (3095) were anophelines and 77.38% (10,586) were culicines. Out of the 3095 anophelines collected, An. gambiae s.l. was predominant (99.48%, n = 3079), followed by Anopheles rufipes (0.45%, n = 14), and Anopheles pharoensis (0.064%, n = 2). Sibling species of the An. gambiae consisted of Anopheles coluzzii (71%), followed by An. gambiae s.s. (23%), and Anopheles melas (6%). Anopheles mean larval density was highest in wells [6.44 (95% CI 5.0-8.31) larvae/dip], lowest in furrows [4.18 (95% CI 2.75-6.36) larvae/dip] and man-made ponds [1.20 (95% CI 0.671-2.131) larvae/dip].The results also revealed habitat stability was highly dependent on rainfall intensity, and Anopheles larval densities were also dependent on elevated levels of pH, conductivity and TDS. CONCLUSION The presence of larvae in the habitats was dependent on rainfall intensity and proximity to human settlements. To optimize the vector control measures of malaria interventions in southern Ghana, larval control should be focused on larval habitats that are fed by underground water, as these are more productive habitats.
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Affiliation(s)
- Akua O Forson
- Department of Medical Laboratory Science, School of Biomedical and Allied Health Sciences, University of Ghana, Korle-Bu, Accra, Ghana
| | - Isaac A Hinne
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Isaac Kwame Sraku
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana.
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Orondo PW, Wang X, Lee MC, Nyanjom SG, Atieli H, Ondeto BM, Ochwedo KO, Omondi CJ, Otambo WO, Zhou G, Zhong D, Githeko AK, Kazura JW, Yan G. Habitat Diversity, Stability, and Productivity of Malaria Vectors in Irrigated and Nonirrigated Ecosystems in Western Kenya. JOURNAL OF MEDICAL ENTOMOLOGY 2023; 60:202-212. [PMID: 36334018 PMCID: PMC9835762 DOI: 10.1093/jme/tjac168] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Indexed: 06/16/2023]
Abstract
Several sub-Saharan African countries rely on irrigation for food production. This study examined the impact of environmental modifications resulting from irrigation on the ecology of aquatic stages of malaria vectors in a semi-arid region of western Kenya. Mosquito larvae were collected from irrigated and non-irrigated ecosystems during seasonal cross-sectional and monthly longitudinal studies to assess habitat availability, stability, and productivity of anophelines in temporary, semipermanent, and permanent habitats during the dry and wet seasons. The duration of habitat stability was also compared between selected habitats. Emergence traps were used to determine the daily production of female adult mosquitoes from different habitat types. Malaria vectors were morphologically identified and sibling species subjected to molecular analysis. Data was statistically compared between the two ecosystems. After aggregating the data, the overall malaria vector productivity for habitats in the two ecosystems was estimated. Immatures of the malaria vector (Anopheles arabiensis) Patton (Diptera: Culicidae) comprised 98.3% of the Anopheles in both the irrigated and non-irrigated habitats. The irrigated ecosystem had the most habitats, higher larval densities, and produced 85.8% of emerged adult females. These results showed that irrigation provided conditions that increased habitat availability, stability, and diversity, consequently increasing the An. arabiensis production and potential risk of malaria transmission throughout the year. The irrigated ecosystems increased the number of habitats suitable for Anopheles breeding by about 3-fold compared to non-irrigated ecosystems. These results suggest that water management in the irrigation systems of western Kenya would serve as an effective method for malaria vector control.
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Affiliation(s)
- Pauline Winnie Orondo
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Xiaoming Wang
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Steven G Nyanjom
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Harrysone Atieli
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Benyl M Ondeto
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Kevin O Ochwedo
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Collince J Omondi
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | | | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Andrew K Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - James W Kazura
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
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Karisa J, Ominde K, Muriu S, Munyao V, Mwikali K, Babu L, Ondieki Z, Bartilol B, Tuwei M, Wanjiku C, Maia M, Midega J, Rono M, Peshu N, Mbogo C, Mwangangi JM. Malaria vector bionomics in Taita-Taveta County, coastal Kenya. Parasit Vectors 2022; 15:430. [DOI: 10.1186/s13071-022-05527-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 10/05/2022] [Indexed: 11/17/2022] Open
Abstract
Abstract
Background
Estimation of the composition and densities of mosquito species populations is crucial for monitoring the epidemiology of mosquito-borne diseases and provide information on local vectors to public health officials and policy-makers. The aim of this study was to evaluate malaria vector bionomics in ecologically distinct sites in Taita-Taveta County, Kenya.
Methods
Adult mosquitoes were collected using backpack aspirators and paired indoor/outdoor CDC light traps in 10 randomly selected households in six villages with distinct ecologies over a study period of 3 years. All Anopheles mosquitoes were morphotyped, and sibling species of Anopheles gambiae sensu lato (An. gambiae s.l.) were identified and separated by PCR analysis of extracted ribosomal DNA. All female anophelines were tested for sporozoite infectivity, with engorged females screened for blood-meal sources using the enzyme-linked immunosorbent assay technique. A subsample of those testing positive and those testing negative for Plasmodium in the ELISA were subjected to PCR assay.
Results
A total of eight different Anopheles species were collected both indoors and outdoors. Anopheles gambiae s.l. (82.6%, n = 5252) was the predominant species sensu lato, followed by Anopheles coustani sensu lato (An. coustani s.l.; (10.5%, n = 666) and Anopheles funestus sensu lato (An. funestus s.l.; 5.6%, n = 357). A subset of 683 mosquito samples representing An. gambiae s.l. (n = 580, approx. 11.0%) and An. funestus s.l. (n = 103, approx. 28.9%) were identified by molecular diagnostic assays into sibling species. The An. gambiae s.l. complex was composed of Anopheles arabiensis (62.5%, n = 363/580), An. gambiae sensu stricto (An. gambiae s.s.; 0.7%, n = 4/580), Anopheles merus (0.7%, n = 4/580) and Anopheles quadriannulatus (0.2%, n = 1/580), with the remaining samples (35.5%, n = 206/580) unamplified. Anopheles funestus s.l. was composed of An. rivulorum (14.6%, n = 15/103) and An. leesoni (11.6%, n = 12/103); the remaining samples were unamplified (73.8%, n = 76/103). A total of 981 samples were subjected to PCR analysis for malaria parasite detection; of these 16 (1.6%) were confirmed to be positive for Plasmodium falciparum. The overall human blood index was 0.13 (32/238).
Conclusions
Anopheles gambiae, An. funestus and An. coustani are key malaria vectors in the Taveta region of Kenya, showing concurrent indoor and outdoor transmission. All of the vectors tested showed a higher propensity for bovine and goat blood than for human blood.
Graphical Abstract
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Zhou G, Hemming-Schroeder E, Jeang B, Wang X, Zhong D, Lee MC, Li Y, Bradley L, Gobran SR, David RE, Ondeto BM, Orondo P, Atieli H, Githure JI, Githeko AK, Kazura J, Yan G. Irrigation-Induced Environmental Changes Sustain Malaria Transmission and Compromise Intervention Effectiveness. J Infect Dis 2022; 226:1657-1666. [PMID: 36056912 DOI: 10.1093/infdis/jiac361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 09/01/2022] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Irrigated agriculture enhances food security, but it potentially promotes mosquito-borne disease transmission and affects vector intervention effectiveness. This study was conducted in the irrigated and nonirrigated areas of rural Homa Bay and Kisumu Counties, Kenya. METHODS We performed cross-sectional and longitudinal surveys to determine Plasmodium infection prevalence, clinical malaria incidence, molecular force of infection (molFOI), and multiplicity of infection. We examined the impact of irrigation on the effectiveness of the new interventions. RESULTS We found that irrigation was associated with >2-fold higher Plasmodium infection prevalence and 3-fold higher clinical malaria incidence compared to the nonirrigated area. Residents in the irrigated area experienced persistent, low-density parasite infections and higher molFOI. Addition of indoor residual spraying was effective in reducing malaria burden, but the reduction was more pronounced in the nonirrigated area than in the irrigated area. CONCLUSIONS Our findings collectively suggest that irrigation may sustain and enhance Plasmodium transmission and affects intervention effectiveness.
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Affiliation(s)
- Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA
| | - Elizabeth Hemming-Schroeder
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA.,Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Brook Jeang
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA
| | - Xiaoming Wang
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA
| | - Yiji Li
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA.,Department of Pathogen Biology, Hainan Medical University, Haikou, China
| | - Lauren Bradley
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA
| | - Sabrina R Gobran
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA
| | - Randy E David
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA
| | - Benyl M Ondeto
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Pauline Orondo
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Harrysone Atieli
- School of Public Health and Community Development, Maseno University, Kisumu, Kenya.,International Center of Excellence for Malaria Research, Tom Mboya University College, Homa Bay, Kenya
| | - John I Githure
- International Center of Excellence for Malaria Research, Tom Mboya University College, Homa Bay, Kenya
| | - Andrew K Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - James Kazura
- Center for Global Health and Disease, Case Western Reserve University, Cleveland, Ohio, USA
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, California, USA
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Urio NH, Pinda PG, Ngonzi AJ, Muyaga LL, Msugupakulya BJ, Finda M, Matanila GS, Mponzi W, Ngowo HS, Kahamba NF, Nkya TE, Okumu FO. Effects of agricultural pesticides on the susceptibility and fitness of malaria vectors in rural south-eastern Tanzania. Parasit Vectors 2022; 15:213. [PMID: 35710443 PMCID: PMC9204902 DOI: 10.1186/s13071-022-05318-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 05/03/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Agricultural pesticides may exert strong selection pressures on malaria vectors during the aquatic life stages and may contribute to resistance in adult mosquitoes. This could reduce the performance of key vector control interventions such as indoor-residual spraying and insecticide-treated nets. The aim of this study was to investigate effects of agrochemicals on susceptibility and fitness of the malaria vectors across farming areas in Tanzania. METHODS An exploratory mixed-methods study was conducted to assess pesticide use in four villages (V1-V4) in south-eastern Tanzania. Anopheles gambiae (s.l.) larvae were collected from agricultural fields in the same villages and their emergent adults examined for insecticide susceptibility, egg-laying and wing lengths (as proxy for body size). These tests were repeated using two groups of laboratory-reared An. arabiensis, one of which was pre-exposed for 48 h to sub-lethal aquatic doses of agricultural pesticides found in the villages. RESULTS Farmers lacked awareness about the linkages between the public health and agriculture sectors but were interested in being more informed. Agrochemical usage was reported as extensive in V1, V2 and V3 but minimal in V4. Similarly, mosquitoes from V1 to V3 but not V4 were resistant to pyrethroids and either pirimiphos-methyl or bendiocarb, or both. Adding the synergist piperonyl butoxide restored potency of the pyrethroids. Pre-exposure of laboratory-reared mosquitoes to pesticides during aquatic stages did not affect insecticide susceptibility in emergent adults of the same filial generation. There was also no effect on fecundity, except after pre-exposure to organophosphates, which were associated with fewer eggs and smaller mosquitoes. Wild mosquitoes were smaller than laboratory-reared ones, but fecundity was similar. CONCLUSIONS Safeguarding the potential of insecticide-based interventions requires improved understanding of how agricultural pesticides influence important life cycle processes and transmission potential of mosquito vectors. In this study, susceptibility of mosquitoes to public health insecticides was lower in villages reporting frequent use of pesticides compared to villages with little or no pesticide use. Variations in the fitness parameters, fecundity and wing length marginally reflected the differences in exposure to agrochemicals and should be investigated further. Pesticide use may exert additional life cycle constraints on mosquito vectors, but this likely occurs after multi-generational exposures.
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Affiliation(s)
- Naomi H. Urio
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Life Science and Bioengineering, The Nelson Mandela African Institute of Science and Technology, P.O. Box 447, Arusha, Tanzania
| | - Polius G. Pinda
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Amos J. Ngonzi
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Life Science and Bioengineering, The Nelson Mandela African Institute of Science and Technology, P.O. Box 447, Arusha, Tanzania
| | - Letus L. Muyaga
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Betwel J. Msugupakulya
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Marceline Finda
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Godfrey S. Matanila
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Winifrida Mponzi
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Halfan S. Ngowo
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health, and Comparative Medicine, University of Glasgow, G12 8QQ Glasgow, Scotland
| | - Najat F. Kahamba
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health, and Comparative Medicine, University of Glasgow, G12 8QQ Glasgow, Scotland
| | - Theresia E. Nkya
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
- University of Dar es Salaam, Mbeya Health and Allied Sciences, Mbeya, Tanzania
| | - Fredros O. Okumu
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Life Science and Bioengineering, The Nelson Mandela African Institute of Science and Technology, P.O. Box 447, Arusha, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Institute of Biodiversity, Animal Health, and Comparative Medicine, University of Glasgow, G12 8QQ Glasgow, Scotland
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Influence of habitat complexity on the prey mortality in IGP system involving insect predators (Heteroptera) and prey (Diptera): Implications in biological control. PLoS One 2022; 17:e0264840. [PMID: 35286333 PMCID: PMC8920208 DOI: 10.1371/journal.pone.0264840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 02/17/2022] [Indexed: 11/30/2022] Open
Abstract
Intraguild predation (IGP) is common in the freshwater insect communities, involving a top predator, intraguild prey (IG prey) and a shared prey. Influence of the habitat complexity on the prey-predator interactions is well established through several studies. In the present instance, the IGP involving the heteropteran predators and the dipteran prey were assessed in the background of the habitat complexity. The three predators Diplonychus rusticus, Ranatra filiformis, and Laccotrephes griseus, one intraguild prey Anisops bouvieri and two dipteran prey Culex quinquefasciatus and Chironomus sp. were used in different relative density against the complex habitat conditions to deduce the impact on the mortality on the prey. In comparison to the open conditions, the presence of the macrophytes and pebbles reduced the mortality of the shared prey under intraguild system as well as single predator system. The mortality of the shared prey was however dependent on the density of the predator and prey. Considering the shared prey mortality, predation on mosquito larvae was always higher in single predator system than chironomid larvae irrespective of identity and density of predators. However, for both the shared prey, complexity of habitat reduced the prey vulnerability in comparison to the simple habitat condition. Higher observed prey consumption depicts the higher risk to predation of shared prey, though the values varied with habitat conditions. Mortality of IG prey (A. bouvieri) in IGP system followed the opposite trend of the shared prey. The lower mortality in simple habitat and higher mortality in complex habitat conditions was observed for the IG prey, irrespective of shared prey and predator density. In IGP system, the shared prey mortality was influenced by the habitat conditions, with more complex habitat reducing the vulnerability of the shared prey and increased mortality of the IG prey. This implies that the regulation of the mosquitoes, in the IGP system will be impeded by the habitat conditions, with the heteropteran predators as the top predator.
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Mitchell CL, Ngasala B, Janko MM, Chacky F, Edwards JK, Pence BW, Mohamed A, Mhamilawa LE, Makene T, Kyaw T, Molteni F, Mkali H, Nyinondi S, Kabula B, Serbantez N, Eckert EL, Kitojo C, Reaves E, Emch M, Juliano JJ. Evaluating malaria prevalence and land cover across varying transmission intensity in Tanzania using a cross-sectional survey of school-aged children. Malar J 2022; 21:80. [PMID: 35264152 PMCID: PMC8905829 DOI: 10.1186/s12936-022-04107-8] [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: 12/13/2021] [Accepted: 02/24/2022] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Transmission of malaria in sub-Saharan Africa has become increasingly stratified following decades of malaria control interventions. The extent to which environmental and land cover risk factors for malaria may differ across distinct strata of transmission intensity is not well known and could provide actionable targets to maximize the success of malaria control efforts. METHODS This study used cross-sectional malaria survey data from a nationally representative cohort of school-aged children in Tanzania, and satellite-derived measures for environmental features and land cover. Hierarchical logistic regression models were applied to evaluate associations between land cover and malaria prevalence within three distinct strata of transmission intensity: low and unstable, moderate and seasonal, and high and perennial. RESULTS In areas with low malaria transmission, each 10-percentage point increase in cropland cover was associated with an increase in malaria prevalence odds of 2.44 (95% UI: 1.27, 5.11). However, at moderate and higher levels of transmission intensity, no association between cropland cover and malaria prevalence was detected. Small associations were observed between greater grassland cover and greater malaria prevalence in high intensity settings (prevalence odds ratio (POR): 1.10, 95% UI: 1.00, 1.21), and between greater forest cover and reduced malaria prevalence in low transmission areas (POR: 0.74, 95% UI: 0.51, 1.03), however the uncertainty intervals of both estimates included the null. CONCLUSIONS The intensity of malaria transmission appears to modify relationships between land cover and malaria prevalence among school-aged children in Tanzania. In particular, greater cropland cover was positively associated with increased malaria prevalence in areas with low transmission intensity and presents an actionable target for environmental vector control interventions to complement current malaria control activities. As areas are nearing malaria elimination, it is important to re-evaluate environmental risk factors and employ appropriate interventions to effectively address low-level malaria transmission.
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Affiliation(s)
- Cedar L. Mitchell
- grid.410711.20000 0001 1034 1720Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Billy Ngasala
- grid.25867.3e0000 0001 1481 7466Muhimbili University of Health and Allied Sciences, Dar es Salam, Tanzania
| | - Mark M. Janko
- grid.34477.330000000122986657Institute for Health Metrics and Evaluation, University of Washington, Washington, USA
| | - Frank Chacky
- grid.490706.cGender, Elderly and Children, Ministry of Health, Community Development, Dodoma, Tanzania ,grid.415734.00000 0001 2185 2147National Malaria Control Programme, Dodoma, Tanzania
| | - Jessie K. Edwards
- grid.410711.20000 0001 1034 1720Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Brian W. Pence
- grid.410711.20000 0001 1034 1720Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Ally Mohamed
- grid.490706.cGender, Elderly and Children, Ministry of Health, Community Development, Dodoma, Tanzania ,grid.415734.00000 0001 2185 2147National Malaria Control Programme, Dodoma, Tanzania
| | - Lwidiko E. Mhamilawa
- grid.25867.3e0000 0001 1481 7466Muhimbili University of Health and Allied Sciences, Dar es Salam, Tanzania
| | - Twilumba Makene
- grid.25867.3e0000 0001 1481 7466Muhimbili University of Health and Allied Sciences, Dar es Salam, Tanzania
| | - Thwai Kyaw
- grid.10698.360000000122483208Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Fabrizio Molteni
- grid.490706.cGender, Elderly and Children, Ministry of Health, Community Development, Dodoma, Tanzania ,Tropical and Public Health Institute, Basel, Switzerland
| | | | | | | | - Naomi Serbantez
- US President’s Malaria Initiative (PMI), United States Agency for International Development, Dar es Salaam, Tanzania
| | - Erin L. Eckert
- grid.62562.350000000100301493RTI International, Washington, DC USA
| | - Chonge Kitojo
- US President’s Malaria Initiative (PMI), United States Agency for International Development, Dar es Salaam, Tanzania
| | - Erik Reaves
- President’s Malaria Initiative, U.S. Centers for Disease Control and Prevention, Dar es Salaam, Tanzania
| | - Michael Emch
- grid.410711.20000 0001 1034 1720Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA ,grid.410711.20000 0001 1034 1720Department of Geography, University of North Carolina, Chapel Hill, NC USA
| | - Jonathan J. Juliano
- grid.10698.360000000122483208Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
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Shah HA, Carrasco LR, Hamlet A, Murray KA. Exploring agricultural land-use and childhood malaria associations in sub-Saharan Africa. Sci Rep 2022; 12:4124. [PMID: 35260722 PMCID: PMC8904834 DOI: 10.1038/s41598-022-07837-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 02/24/2022] [Indexed: 11/09/2022] Open
Abstract
Agriculture in Africa is rapidly expanding but with this comes potential disbenefits for the environment and human health. Here, we retrospectively assess whether childhood malaria in sub-Saharan Africa varies across differing agricultural land uses after controlling for socio-economic and environmental confounders. Using a multi-model inference hierarchical modelling framework, we found that rainfed cropland was associated with increased malaria in rural (OR 1.10, CI 1.03-1.18) but not urban areas, while irrigated or post flooding cropland was associated with malaria in urban (OR 1.09, CI 1.00-1.18) but not rural areas. In contrast, although malaria was associated with complete forest cover (OR 1.35, CI 1.24-1.47), the presence of natural vegetation in agricultural lands potentially reduces the odds of malaria depending on rural-urban context. In contrast, no associations with malaria were observed for natural vegetation interspersed with cropland (veg-dominant mosaic). Agricultural expansion through rainfed or irrigated cropland may increase childhood malaria in rural or urban contexts in sub-Saharan Africa but retaining some natural vegetation within croplands could help mitigate this risk and provide environmental co-benefits.
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Affiliation(s)
- Hiral Anil Shah
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK. .,Grantham Institute - Climate Change and the Environment - Imperial College London, London, UK.
| | - Luis Roman Carrasco
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Arran Hamlet
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Kris A Murray
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK.,MRC Unit The Gambia at London, School of Hygiene and Tropical Medicine, Atlantic Boulevard, Fajara, The Gambia.,Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London, UK
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12
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Mwagira-Maina S, Runo S, Wachira L, Kitur S, Nyasende S, Kemei B, Ochomo E, Matoke-Muhia D, Mbogo C, Kamau L. Genetic markers associated with insecticide resistance and resting behaviour in Anopheles gambiae mosquitoes in selected sites in Kenya. Malar J 2021; 20:461. [PMID: 34903240 PMCID: PMC8670025 DOI: 10.1186/s12936-021-03997-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 11/28/2021] [Indexed: 11/16/2022] Open
Abstract
Background Molecular diagnostic tools have been incorporated in insecticide resistance monitoring programmes to identify underlying genetic basis of resistance and develop early warning systems of vector control failure. Identifying genetic markers of insecticide resistance is crucial in enhancing the ability to mitigate potential effects of resistance. The knockdown resistance (kdr) mutation associated with resistance to DDT and pyrethroids, the acetylcholinesterase-1 (ace-1R) mutation associated with resistance to organophosphates and carbamates and 2La chromosomal inversion associated with indoor resting behaviour, were investigated in the present study. Methods Anopheles mosquitoes sampled from different sites in Kenya and collected within the context of malaria vector surveillance were analysed. Mosquitoes were collected indoors using light traps, pyrethrum spray and hand catches between August 2016 and November 2017. Mosquitoes were identified using morphological keys and Anopheles gambiae sensu lato (s.l.) mosquitoes further identified into sibling species by the polymerase chain reaction method following DNA extraction by alcohol precipitation. Anopheles gambiae and Anopheles arabiensis were analysed for the presence of the kdr and ace-1R mutations, while 2La inversion was only screened for in An. gambiae where it is polymorphic. Chi-square statistics were used to determine correlation between the 2La inversion karyotype and kdr-east mutation. Results The kdr-east mutation occurred at frequencies ranging from 0.5 to 65.6% between sites. The kdr-west mutation was only found in Migori at a total frequency of 5.3% (n = 124). No kdr mutants were detected in Tana River. The ace-1R mutation was absent in all populations. The 2La chromosomal inversion screened in An. gambiae occurred at frequencies of 87% (n = 30), 80% (n = 10) and 52% (n = 50) in Baringo, Tana River and Migori, respectively. A significant association between the 2La chromosomal inversion and the kdr-east mutation was found. Conclusion The significant association between the 2La inversion karyotype and kdr-east mutation suggests that pyrethroid resistant An. gambiae continue to rest indoors regardless of the presence of treated bed nets and residual sprays, a persistence further substantiated by studies documenting continued mosquito abundance indoors. Behavioural resistance by which Anopheles vectors prefer not to rest indoors may, therefore, not be a factor of concern in this study’s malaria vector populations.
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Affiliation(s)
- Sharon Mwagira-Maina
- Department of Biochemistry and Biotechnology, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya.
| | - Steven Runo
- Department of Biochemistry and Biotechnology, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya
| | - Lucy Wachira
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Stanley Kitur
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Sarah Nyasende
- Institute of Tropical Medicine and Infectious Diseases (ITROMID), P.O. Box 54840-00200, Nairobi, Kenya
| | - Brigid Kemei
- Centre for Global Health Research, KEMRI_CDC, P.O Box 1578-40100, Kisumu, Kenya
| | - Eric Ochomo
- Centre for Global Health Research, KEMRI_CDC, P.O Box 1578-40100, Kisumu, Kenya
| | - Damaris Matoke-Muhia
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Charles Mbogo
- KEMRI -Wellcome Trust Research Programme, Public Health Unit, P.O. Box 43640-00100, Nairobi, Kenya
| | - Luna Kamau
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
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13
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Grass-like plants release general volatile cues attractive for gravid Anopheles gambiae sensu stricto mosquitoes. Parasit Vectors 2021; 14:552. [PMID: 34706760 PMCID: PMC8554987 DOI: 10.1186/s13071-021-04939-4] [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: 06/21/2021] [Accepted: 08/09/2021] [Indexed: 11/16/2022] Open
Abstract
Background Understanding the ecology and behaviour of disease vectors, including the olfactory cues used to orient and select hosts and egg-laying sites, are essential for the development of novel, insecticide-free control tools. Selected graminoid plants have been shown to release volatile chemicals attracting malaria vectors; however, whether the attraction is selective to individual plants or more general across genera and families is still unclear. Methods To contribute to the current evidence, we implemented bioassays in two-port airflow olfactometers and in large field cages with four live graminoid plant species commonly found associated with malaria vector breeding sites in western Kenya: Cyperus rotundus and C. exaltatus of the Cyperaceae family, and Panicum repens and Cynodon dactylon of the Poaceae family. Additionally, we tested one Poaceae species, Cenchrus setaceus, not usually associated with water. The volatile compounds released in the headspace of the plants were identified using gas chromatography/mass spectrometry. Results All five plants attracted gravid vectors, with the odds of a mosquito orienting towards the choice-chamber with the plant in an olfactometer being 2–5 times higher than when no plant was present. This attraction was maintained when tested with free-flying mosquitoes over a longer distance in large field cages, though at lower strength, with the odds of attracting a female 1.5–2.5 times higher when live plants were present than when only water was present in the trap. Cyperus rotundus, previously implicated in connection with an oviposition attractant, consistently elicited the strongest response from gravid vectors. Volatiles regularly detected were limonene, β-pinene, β-elemene and β-caryophyllene, among other common plant compounds previously described in association with odour-orientation of gravid and unfed malaria vectors. Conclusions The present study confirms that gravid Anopheles gambiae sensu stricto use chemical cues released from graminoid plants to orientate. These cues are released from a variety of graminoid plant species in both the Cyperaceae and Poaceae family. Given the general nature of these cues, it appears unlikely that they are exclusively used for the location of suitable oviposition sites. The utilization of these chemical cues for attract-and-kill trapping strategies must be explored under natural conditions to investigate their efficiency when in competition with complex interacting natural cues. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04939-4.
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Orondo PW, Nyanjom SG, Atieli H, Githure J, Ondeto BM, Ochwedo KO, Omondi CJ, Kazura JW, Lee MC, Zhou G, Zhong D, Githeko AK, Yan G. Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya. Parasit Vectors 2021; 14:335. [PMID: 34174946 PMCID: PMC8235622 DOI: 10.1186/s13071-021-04833-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 06/09/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya. METHODS The study was carried out in 2018-2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area. RESULTS Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8-84% to 83.3-78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1-16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection. CONCLUSION Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides.
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Affiliation(s)
- Pauline Winnie Orondo
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya. .,International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya.
| | - Steven G Nyanjom
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Harrysone Atieli
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya.,School of Public Health and Community Development, Maseno University, Kisumu, Kenya
| | - John Githure
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Benyl M Ondeto
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Kevin O Ochwedo
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Collince J Omondi
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - James W Kazura
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Andrew K Githeko
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya. .,Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA.
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Hinne IA, Attah SK, Mensah BA, Forson AO, Afrane YA. Larval habitat diversity and Anopheles mosquito species distribution in different ecological zones in Ghana. Parasit Vectors 2021; 14:193. [PMID: 33827667 PMCID: PMC8025514 DOI: 10.1186/s13071-021-04701-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/23/2021] [Indexed: 11/16/2022] Open
Abstract
Background Understanding the ecology of larval malaria and lymphatic filariasis mosquitoes in a changing environment is important in developing effective control tools or programmes. This study characterized the breeding habitats of Anopheles mosquitoes in rural communities in different ecological zones in Ghana during the dry and rainy seasons. Methods The spatio-temporal distribution, species composition, and abundance of larval Anopheles mosquitoes in breeding habitats were studied in five locations in three ecological zones of Ghana. These were Anyakpor (coastal savannah area), Duase (forest area), and Libga, Pagaza, and Kpalsogu (Sahel savannah area). Larvae were collected using standard dippers and were raised in the insectary for identification. Results Out of a total of 7984 mosquito larvae collected, 2152 (27.26%) were anophelines and were more abundant in the rainy season (70.82%) than in the dry season (29.18%). The anophelines comprised 2128 (98.88%) An. gambiae s.l., 16 (0.74%) An. rufipes, and 8 (0.37%) An. pharoensis. In the coastal savannah and forest zones, dug-out wells were the most productive habitat during the dry (1.59 larvae/dip and 1.47 larvae/dip) and rainy seasons (11.28 larvae/dip and 2.05 larvae/dip). Swamps and furrows were the most productive habitats in the Sahel savannah zone during the dry (0.25 larvae/dip) and rainy (2.14 larvae/dip) seasons, respectively. Anopheles coluzzii was the most abundant sibling species in all the ecological zones. Anopheles melas and An. arabiensis were encountered only in the coastal savannah and the Sahel savannah areas, respectively. Larval habitat types influenced the presence of larvae as well as larval density (p < 0.001). The land-use type affected the presence of Anopheles larvae (p = 0.001), while vegetation cover influenced larval density (p < 0.05). Conclusion The most productive habitats were dug-out wells in the coastal savannah and forest zones, and furrows from irrigated canals in the Sahel savannah zone. Anopheles coluzzii was the predominant vector species in all the ecological zones. The abundance of Anopheles breeding habitats and larvae were influenced by anthropogenic activities. Encouraging people whose activities create the larval habitats to become involved in larval source management such as habitat manipulation to stop mosquito breeding will be important for malaria and lymphatic filariasis control. Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04701-w.
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Affiliation(s)
- Isaac A Hinne
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Simon K Attah
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Benedicta A Mensah
- Department of Epidemiology, Noguchi Memorial Institute of Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Akua O Forson
- Department of Medical Laboratory Science, School of Biomedical and Allied Health Sciences, University of Ghana, Korle-Bu, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana.
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Munyao V, Karisa J, Munyao CM, Ngari M, Menza N, Peshu N, Rono M, Mbogo C, Mwangangi J. Surveillance of Culicine Mosquitoes in Six Villages of Taita-Taveta County, Kenya, With Host Determinations From Blood-Fed Females. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:1972-1982. [PMID: 32533693 PMCID: PMC7613318 DOI: 10.1093/jme/tjaa109] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Indexed: 06/11/2023]
Abstract
Culicine mosquitoes are vectors of human disease-causing pathogens like filarial worms and several arthropod-borne viruses (arboviruses). Currently, there has been an increase in emerging and re-emerging vector-borne diseases along coastal Kenya, which has been of major concern in public health. This study aimed at determining culicine mosquito species abundance, diversity and their host feeding preferences in Taita-Taveta County, Coastal Kenya. Entomological sampling was done during the long-wet season (March and May) and long dry season (June to October) 2016-2018. Mosquito sampling was done using CDC light traps and Backpack aspiration for indoor and outdoor environments. All culicine mosquitoes collected were identified morphologically and categorized according to their physiological status. Blood fed culicine mosquitoes were tested for bloodmeal sources using ELISA. In total, 3,278 culicine mosquitoes were collected, of which 738 (22.5 %) were found indoors and 2,540, (77.5 %) outdoors. The mosquitoes consisted of 18 species belonging to four genera: Aedes (7), Culex (8), Mansonia (2), and Coquillettidia (1). Overall, there was high mosquito species diversity (H) in outdoors (H = 2.4339) than in indoors (H = 2.2523), whereas even distribution (EH) was higher in indoors (EH = 0.9064) than outdoors (EH = 0.8266). Majorly the bloodmeals identified were from multiple host sources with (51.6%), single hosts (41.3%), and unidentified (7.2%). This study has demonstrated a high diversity of culicine mosquitoes with relaxed feeding tendencies. These mosquitoes are contributing to mosquito biting nuisance and the likelihood of exposure of populations to diseases of public health.
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Affiliation(s)
- Vanessa Munyao
- Department of Medical Laboratory Sciences, Kenyatta University, Nairobi, Kenya
- Kenya Medical Research Institute (KEMRI), Center for Geographic Medicine Coast, Kilifi, Kenya
| | - Jonathan Karisa
- Kenya Medical Research Institute (KEMRI), Center for Geographic Medicine Coast, Kilifi, Kenya
- Pwani University Bioscience Research Centre (PUBreC), Kilifi, Kenya
| | | | - Moses Ngari
- Kenya Medical Research Institute (KEMRI), Center for Geographic Medicine Coast, Kilifi, Kenya
| | - Nelson Menza
- Department of Medical Laboratory Sciences, Kenyatta University, Nairobi, Kenya
| | - Norbert Peshu
- Kenya Medical Research Institute (KEMRI), Center for Geographic Medicine Coast, Kilifi, Kenya
| | - Martin Rono
- Kenya Medical Research Institute (KEMRI), Center for Geographic Medicine Coast, Kilifi, Kenya
- Pwani University Bioscience Research Centre (PUBreC), Kilifi, Kenya
| | - Charles Mbogo
- Kenya Medical Research Institute (KEMRI), Center for Geographic Medicine Coast, Kilifi, Kenya
| | - Joseph Mwangangi
- Kenya Medical Research Institute (KEMRI), Center for Geographic Medicine Coast, Kilifi, Kenya
- Pwani University Bioscience Research Centre (PUBreC), Kilifi, Kenya
- KEMRI, Center for Vector Disease Control, Kwale, Kenya
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Demissew A, Hawaria D, Kibret S, Animut A, Tsegaye A, Lee MC, Yan G, Yewhalaw D. Impact of sugarcane irrigation on malaria vector Anopheles mosquito fauna, abundance and seasonality in Arjo-Didessa, Ethiopia. Malar J 2020; 19:344. [PMID: 32962693 PMCID: PMC7510110 DOI: 10.1186/s12936-020-03416-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/10/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Despite extensive irrigation development in Ethiopia, limited studies assessed the impact of irrigation on malaria vector mosquito composition, abundance and seasonality. This study aimed to evaluate the impact of sugarcane irrigation on species composition, abundance and seasonality of malaria vectors. METHODS Adult Anopheles mosquitoes were collected using CDC light traps from three irrigated and three non-irrigated clusters in and around Arjo-Didessa sugarcane irrigation scheme in southwestern Ethiopia. Mosquitoes were surveyed in four seasons: two wet and two dry, in 2018 and 2019. Mosquito species composition, abundance and seasonality were compared between irrigated and non-irrigated clusters. Anopheles mosquitoes were sorted out to species using morphological keys and molecular techniques. Chi square was used to test the relationships between Anopheles species occurrence, and environmental and seasonal parameters. RESULTS Overall, 2108 female Anopheles mosquitoes comprising of six species were collected. Of these, 92.7% (n = 1954) were from irrigated clusters and 7.3% (n = 154) from the non-irrigated. The Anopheles gambiae complex was the most abundant (67.3%) followed by Anopheles coustani complex (25.3%) and Anopheles pharoensis (5.7%). PCR-based identification revealed that 74.7% (n = 168) of the An. gambiae complex were Anopheles arabiensis and 22.7% (n = 51) Anopheles amharicus. The density of An. gambiae complex (both indoor and outdoor) was higher in irrigated than non-irrigated clusters. The overall anopheline mosquito abundance during the wet seasons (87.2%; n = 1837) was higher than the dry seasons (12.8%; n = 271). CONCLUSION The ongoing sugarcane irrigation activities in Arjo-Didessa created conditions suitable for malaria transmitting Anopheles species diversity and abundance. This could drive malaria transmission in Arjo-Didessa and its environs in both dry and wet seasons. Currently practiced malaria vector interventions need to be strengthened by including larval source management to reduce vector abundance in the irrigated areas.
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Affiliation(s)
- Assalif Demissew
- Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Ambo University, Ambo, Ethiopia. .,Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
| | - Dawit Hawaria
- Yirgalem Hospital Medical College, Yirgalem, Ethiopia.,School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia.,Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Solomon Kibret
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Abebe Animut
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Arega Tsegaye
- College of Natural Science, Department of Biology, Jimma University, Jimma, Ethiopia.,Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Ming-Cheih Lee
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Guiyun Yan
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia.,Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
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Djègbè I, Zinsou M, Dovonou EF, Tchigossou G, Soglo M, Adéoti R, Gbaguidi B, Atoyebi S, Chandre F, Akogbéto M, Lines J, Djouaka R. Minimal tillage and intermittent flooding farming systems show a potential reduction in the proliferation of Anopheles mosquito larvae in a rice field in Malanville, Northern Benin. Malar J 2020; 19:333. [PMID: 32928223 PMCID: PMC7491134 DOI: 10.1186/s12936-020-03406-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 09/04/2020] [Indexed: 12/05/2022] Open
Abstract
Background Irrigation systems have been identified as one of the factors promoting malaria disease around agricultural farms in sub-Saharan Africa. However, if improved water management strategy is adopted during rice cultivation, it may help to reduce malaria cases among human population living around rice fields. This study aimed to assess the impact of the different irrigation practices on malaria transmission, as well as to evaluate the water management system that will best mitigate malaria transmission in Malanville, Benin. Methods Knowledge, Attitude and Practice (KAP) study was conducted on 104 households staying on and around the rice fields in Malanville. The study focused on the frequency of mosquito bites and preventive measures against malaria as well as soil preparation and rice planting methods. Mosquito larvae density was assessed in different water management system: continuous flooding (CF) or intermittent flooding (IF), deep tillage (DT) or minimal tillage (MT) and normal levelling (NL) or abnormal levelling (AL) in an experimental hut set-up. Larvae were collected using dipping methods and their density was determined. Results Three tillage systems, which include the use of tiller, plow and hoe, were identified on the rice field. Continuous flooding was the only irrigation system used by farmers. Retrospective data from Malanville Health Centre revealed higher malaria cases during rice production season, which was also confirmed by field participants. The density of Anopheles larvae was reduced by 80.8%, 30.8% and 40.7% (P = 0.000) during transplanting, tillering and maturation periods, respectively with intermittent flooding compared to continuous flooding. In addition, a clear reduction of larva density was observed with both intermittent flooding systems applied to minimal tillage (MT + IF + NL) and intermittent flooding applied to deep tillage (DT + IF + AL), showing that intermittent flooding could reduce the abundance of malaria vector in rice fields. Conclusion Recommending intermittent flooding technology for rice cultivation may not only be useful for water management but could also be an intentional strategy to control mosquitoes vector-borne diseases around rice farms.
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Affiliation(s)
- Innocent Djègbè
- National University of Sciences, Technologies, Engineering and Mathematics, Ecole Normale Supérieure de Natitingou, BP 72, Natitingou, Benin.
| | - Merdie Zinsou
- Laboratoire d'Hydrologie Appliquée, University of Abomey-Calavi, Institut National de l'eau, BP 526, Cotonou, Benin.,International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin
| | - Edia Flavien Dovonou
- Laboratoire d'Hydrologie Appliquée, University of Abomey-Calavi, Institut National de l'eau, BP 526, Cotonou, Benin
| | | | - Murielle Soglo
- International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin
| | - Razack Adéoti
- International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin
| | - Brice Gbaguidi
- International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin
| | - Seun Atoyebi
- International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin
| | - Fabrice Chandre
- UMR IRD 224-CNRS 5290-Université de Montpellier. MIVEGEC. Maladies Infectieuses et Vecteurs : Ecologie, Génétique, Evolution et Contrôle, 911 Avenue Agropolis, BP 64501, 34394, Montpellier Cedex 5, France
| | - Martin Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
| | - Jo Lines
- London School of Hygiene and Tropical Medicine, London, UK
| | - Rousseau Djouaka
- International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin
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Samuel M, Brooke BD, Oliver SV. Effects of inorganic fertilizer on larval development, adult longevity and insecticide susceptibility in the malaria vector Anopheles arabiensis (Diptera: Culicidae). PEST MANAGEMENT SCIENCE 2020; 76:1560-1568. [PMID: 31713993 DOI: 10.1002/ps.5676] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 09/28/2019] [Accepted: 11/06/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Exposure to inorganic fertilizer is common for the major malaria vector Anopheles arabiensis, which is closely associated with agricultural activities. The aim of this study was to understand if insecticide susceptible and resistant individuals respond to fertilizer exposure in the same manner. Two laboratory strains, SENN, an insecticide susceptible strain, and SENN-DDT, an insecticide resistant strain selected strain selected from SENN, were used in this study. Both strains were exposed to one of three concentrations of a combination nitrogen-phosphorus-potassium (NPK) inorganic fertilizer, as well as nitrogenous (urea), phosphorus (superphosphate) and kaelic (potassium chloride, KCl) elemental fertilizer. The time to pupation was monitored, adult longevity was assessed and the insecticide tolerance of adults was determined. The effect of elemental fertilizers on ovipositioning site choice was also assessed. RESULTS For both strains, urea increased the number of eggs laid, while superphosphate resulted in a significant decrease in egg laying. Larval NPK exposure decreased the time to pupation in the SENN strain but not in SENN-DDT. Urea exposure increased the time to pupation in both strains, while KCl decreased the time to pupation in both strains. Larval NPK exposure only affected adult male longevity at high concentrations. Larval exposure to NPK and KCl resulted in increased insecticide tolerance in both strains, with variable efficacy from strain to strain. CONCLUSION Exposure to inorganic fertilizers has a greater effect on insecticide susceptible An. arabiensis as compared to resistant strains, where the primary advantage is increased insecticide tolerance. These data also demonstrate that larval fertilizer exposure can affect fecundity and fertility, and alter the life histories of adult An. arabiensis. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Michael Samuel
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Basil D Brooke
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Shüné V Oliver
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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20
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Runge M, Snow RW, Molteni F, Thawer S, Mohamed A, Mandike R, Giorgi E, Macharia PM, Smith TA, Lengeler C, Pothin E. Simulating the council-specific impact of anti-malaria interventions: A tool to support malaria strategic planning in Tanzania. PLoS One 2020; 15:e0228469. [PMID: 32074112 PMCID: PMC7029840 DOI: 10.1371/journal.pone.0228469] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 01/16/2020] [Indexed: 11/25/2022] Open
Abstract
INTRODUCTION The decision-making process for malaria control and elimination strategies has become more challenging. Interventions need to be targeted at council level to allow for changing malaria epidemiology and an increase in the number of possible interventions. Models of malaria dynamics can support this process by simulating potential impacts of multiple interventions in different settings and determining appropriate packages of interventions for meeting specific expected targets. METHODS The OpenMalaria model of malaria dynamics was calibrated for all 184 councils in mainland Tanzania using data from malaria indicator surveys, school parasitaemia surveys, entomological surveillance, and vector control deployment data. The simulations were run for different transmission intensities per region and five interventions, currently or potentially included in the National Malaria Strategic Plan, individually and in combination. The simulated prevalences were fitted to council specific prevalences derived from geostatistical models to obtain council specific predictions of the prevalence and number of cases between 2017 and 2020. The predictions were used to evaluate in silico the feasibility of the national target of reaching a prevalence of below 1% by 2020, and to suggest alternative intervention stratifications for the country. RESULTS The historical prevalence trend was fitted for each council with an agreement of 87% in 2016 (95%CI: 0.84-0.90) and an agreement of 90% for the historical trend (2003-2016) (95%CI: 0.87-0.93) The current national malaria strategy was expected to reduce the malaria prevalence between 2016 and 2020 on average by 23.8% (95% CI: 19.7%-27.9%) if current case management levels were maintained, and by 52.1% (95% CI: 48.8%-55.3%) if the case management were improved. Insecticide treated nets and case management were the most cost-effective interventions, expected to reduce the prevalence by 25.0% (95% CI: 19.7%-30.2) and to avert 37 million cases between 2017 and 2020. Mass drug administration was included in most councils in the stratification selected for meeting the national target at minimal costs, expected to reduce the prevalence by 77.5% (95%CI: 70.5%-84.5%) and to avert 102 million cases, with almost twice higher costs than those of the current national strategy. In summary, the model suggested that current interventions are not sufficient to reach the national aim of a prevalence of less than 1% by 2020 and a revised strategic plan needs to consider additional, more effective interventions, especially in high transmission areas and that the targets need to be revisited. CONCLUSION The methodology reported here is based on intensive interactions with the NMCP and provides a helpful tool for assessing the feasibility of country specific targets and for determining which intervention stratifications at sub-national level will have most impact. This country-led application could support strategic planning of malaria control in many other malaria endemic countries.
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Affiliation(s)
- Manuela Runge
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Robert W. Snow
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, England, United Kingodm
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Fabrizio Molteni
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- National Malaria Control Programme (NMCP), Dar es Salaam, Tanzania
| | - Sumaiyya Thawer
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- National Malaria Control Programme (NMCP), Dar es Salaam, Tanzania
| | - Ally Mohamed
- National Malaria Control Programme (NMCP), Dar es Salaam, Tanzania
| | - Renata Mandike
- National Malaria Control Programme (NMCP), Dar es Salaam, Tanzania
| | - Emanuele Giorgi
- CHICAS, Lancaster Medical School, Lancaster University, Lancaster, England, United Kingodm
| | - Peter M. Macharia
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Thomas A. Smith
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Christian Lengeler
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Emilie Pothin
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- Clinton Health Access Initiative, Boston, Massachusetts, United States of America
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Anopheles larval species composition and characterization of breeding habitats in two localities in the Ghibe River Basin, southwestern Ethiopia. Malar J 2020; 19:65. [PMID: 32046734 PMCID: PMC7014609 DOI: 10.1186/s12936-020-3145-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 01/30/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Documentation of the species composition of Anopheles mosquitoes and characterization of larval breeding sites is of major importance for the implementation of larval control as part of malaria vector control interventions in Ethiopia. The aims of this study were to determine the Anopheles larval species composition, larval density, available habitat types and the effects of related environmental and physico-chemical parameters of habitats in the Ghibe River basin of southwestern Ethiopia. METHODS Anopheles larvae were sampled from November 2014 to October 2016 on a monthly basis and 3rd and 4th instars were identified microscopically to species. The larval habitats were characterized based on habitat perimeter, water depth, intensity of light, water current, water temperature, water pH, water turbidity, distance to the nearest house, vegetation coverage, permanence of the habitat, surface debris coverage, emergent plant coverage, habitat type and substrate type. RESULTS In total, 9277 larvae of Anopheles mosquitoes and 494 pupae were sampled from borrow pits, hoof prints, rain pools, pools at river edges, pools in drying river beds, rock pools, tire tracks and swamps. Anopheles larval density was highest in pools in drying river beds (35.2 larvae per dip) and lowest in swamps (2.1 larvae per dip) at Darge, but highest in rain pools (11.9 larvae per dip), borrow pits (11.2 larvae per dip) and pools at river edges (7.9 larvae per dip), and lowest in swamps (0.5 larvae per dip) at Ghibe. A total of 3485 late instar Anopheles mosquito larvae were morphologically identified. Anopheles gambiae sensu lato was the primary Anopheles mosquito found in all larval habitats except in swamps. Temperature at the time of sampling and emergent vegetation, were the most important variables for Anopheles mosquito larval density. Anopheles gambiae density was significantly associated with habitats that had smaller perimeters, were sunlit, had low vegetation cover, and a lack of emergent plants. Generally, Anopheles mosquito larval density was not significantly associated with water pH, water temperature, water turbidity, algal content, and larval habitat depth. CONCLUSION Different species of Anopheles larvae were identified including An. gambiae s.l., the main malaria vector in Ethiopia. Anopheles gambiae s.l. is the most abundant species that bred in most of the larval habitat types identified in the study area. The density of this species was high in sunlit habitat, absence of emergent plants, lack of vegetation near habitat and habitats closer to human habitation. Rainfall plays a great role in determining the availability of breeding habitats. The presence of rain enable to create some of the habitat types, but alter the habitats formed at the edge of the rivers due to over flooding. Controlling the occurrence of mosquito larvae through larval source management during the dry season, targeting the pools in drying river bed and pools formed at the edge of the rivers as the water receded can be very crucial to interrupt the re-emergence of malaria vectors on the onset of rainy season.
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Taylor DM, Olds CL, Haney RS, Torrevillas BK, Luckhart S. Comprehensive and Durable Modulation of Growth, Development, Lifespan and Fecundity in Anopheles stephensi Following Larval Treatment With the Stress Signaling Molecule and Novel Antimalarial Abscisic Acid. Front Microbiol 2020; 10:3024. [PMID: 32010091 PMCID: PMC6979008 DOI: 10.3389/fmicb.2019.03024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 12/17/2019] [Indexed: 12/19/2022] Open
Abstract
The larval environment of holometabolous insects determines many adult life history traits including, but not limited to, rate and success of development and adult lifespan and fecundity. The ancient stress signaling hormone abscisic acid (ABA), released by plants inundated with water and by leaf and root fragments in water, is likely ubiquitous in the mosquito larval environment and is well known for its wide ranging effects on invertebrate biology. Accordingly, ABA is a relevant stimulus and signal for mosquito development. In our studies, the addition of ABA at biologically relevant levels to larval rearing containers accelerated the time to pupation and increased death of A. stephensi pupae. We could not attribute these effects, however, to ABA-dependent changes in JH biosynthesis-associated gene expression, 20E titers or transcript patterns of insulin-like peptide genes. Adult females derived from ABA-treated larvae had reduced total protein content and significantly reduced post blood meal transcript expression of vitellogenin, effects that were consistent with variably reduced egg clutch sizes and oviposition success from the first through the third gonotrophic cycles. Adult female A. stephensi derived from ABA-treated larvae also exhibited reduced lifespans relative to controls. Collectively, these effects of ABA on A. stephensi life history traits are robust, durable and predictive of multiple impacts of an important malaria vector spreading to new malaria endemic regions.
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Affiliation(s)
- Dean M Taylor
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, ID, United States
| | - Cassandra L Olds
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, ID, United States
| | - Reagan S Haney
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, ID, United States
| | - Brandi K Torrevillas
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, ID, United States
| | - Shirley Luckhart
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, ID, United States.,Department of Biological Sciences, University of Idaho, Moscow, ID, United States
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Madewell ZJ, Sosa S, Brouwer KC, Juárez JG, Romero C, Lenhart A, Cordón-Rosales C. Associations between household environmental factors and immature mosquito abundance in Quetzaltenango, Guatemala. BMC Public Health 2019; 19:1729. [PMID: 31870343 PMCID: PMC6929347 DOI: 10.1186/s12889-019-8102-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/17/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Aedes aegypti-borne diseases are becoming major public health problems in tropical and sub-tropical regions. While socioeconomic status has been associated with larval mosquito abundance, the drivers or possible factors mediating this association, such as environmental factors, are yet to be identified. We examined possible associations between proximity to houses and roads and immature mosquito abundance, and assessed whether these factors and mosquito prevention measures mediated any association between household environmental factors and immature mosquito abundance. METHODS We conducted two cross-sectional household container surveys in February-March and November-December, 2017, in urban and rural areas of Quetzaltenango, Guatemala. We used principal components analysis to identify factors from 12 variables to represent the household environment. One factor which included number of rooms in house, electricity, running water, garbage service, cable, television, telephone, latrine, well, and sewer system, was termed "environmental capital." Environmental capital scores ranged from 0 to 5.5. Risk factors analyzed included environmental capital, and distance from nearest house/structure, paved road, and highway. We used Poisson regression to determine associations between distance to nearest house/structure, roads, and highways, and measures of immature mosquito abundance (total larvae, total pupae, and positive containers). Using cubic spline generalized additive models, we assessed non-linear associations between environmental capital and immature mosquito abundance. We then examined whether fumigation, cleaning containers, and distance from the nearest house, road, and highway mediated the relationship between environmental capital and larvae and pupae abundance. RESULTS We completed 508 household surveys in February-March, and we revisited 469 households in November-December. Proximity to paved roads and other houses/structures was positively associated with larvae and pupae abundance and mediated the associations between environmental capital and total numbers of larvae/pupae (p ≤ 0.01). Distance to highways was not associated with larval/pupal abundance (p ≥ 0.48). Households with the lowest and highest environmental capital had fewer larvae/pupae than households in the middle range (p < 0.01). CONCLUSIONS We found evidence that proximity to other houses and paved roads was associated with greater abundance of larvae and pupae. Understanding risk factors such as these can allow for improved targeting of surveillance and vector control measures in areas considered at higher risk for arbovirus transmission.
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Affiliation(s)
- Zachary J Madewell
- Centro de Estudios en Salud, Universidad del Valle de Guatemala, Guatemala City, Guatemala. .,Program in Public Health (Epidemiology), University of California, San Diego/San Diego State University, San Diego, CA, USA.
| | - Silvia Sosa
- Centro de Estudios en Salud, Universidad del Valle de Guatemala, Guatemala City, Guatemala
| | - Kimberly C Brouwer
- Department of Family Medicine & Public Health, Division of Global Health, University of California, San Diego, CA, USA
| | - José Guillermo Juárez
- Centro de Estudios en Salud, Universidad del Valle de Guatemala, Guatemala City, Guatemala.,Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Carolina Romero
- Centro de Estudios en Salud, Universidad del Valle de Guatemala, Guatemala City, Guatemala
| | - Audrey Lenhart
- Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA
| | - Celia Cordón-Rosales
- Centro de Estudios en Salud, Universidad del Valle de Guatemala, Guatemala City, Guatemala
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Kibret S, Ryder D, Wilson GG, Kumar L. Modeling reservoir management for malaria control in Ethiopia. Sci Rep 2019; 9:18075. [PMID: 31792340 PMCID: PMC6889458 DOI: 10.1038/s41598-019-54536-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 11/07/2019] [Indexed: 11/24/2022] Open
Abstract
This study investigated how changes in reservoir water level affect mosquito abundance and malaria transmission in Ethiopia. Digital elevation models of three Ethiopian dams at lowland, midland and highland elevations were used to quantify water surface area and wetted shoreline at different reservoir water levels (70, 75, 80, 85, 90, 95 and 100% full capacity) to estimate surface area of potential mosquito breeding habitat. Reservoir water level drawdown rates of 10, 15 and 20 mm.day−1 were applied as scenarios to model larval abundance, entomological inoculation rate (EIR) and malaria prevalence at each dam. Malaria treatment cost and economic cost in terms of lost working days were calculated for each water level scenario and dam. At the lowland dam, increased larval abundances were associated with increasing reservoir water level and wetted shoreline area. In contrast, both larval abundances and area of wetted shoreline declined with increasing reservoir water level at the midland and highland dams. Estimated EIR, malaria prevalence, malaria treatment cost and economic cost generally decreased when the water level drawdown rate increased from 10 to 15 and 20 mm.day−1 irrespective of reservoir water level. Given the expansion of dam construction in sub-Saharan Africa, incorporating malaria control measures such as manipulating drawdown rates into reservoir management has the potential to reduce the malaria burden and health care costs in communities near reservoirs.
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Affiliation(s)
- Solomon Kibret
- Ecosystem Management, University of New England, NSW, 2351, Armidale, Australia. .,Program in Public Health, University of California, Irvine, CA, 92697, USA.
| | - Darren Ryder
- Ecosystem Management, University of New England, NSW, 2351, Armidale, Australia
| | - G Glenn Wilson
- Ecosystem Management, University of New England, NSW, 2351, Armidale, Australia.,Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Lalit Kumar
- Ecosystem Management, University of New England, NSW, 2351, Armidale, Australia
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25
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Automatic Detection of Open and Vegetated Water Bodies Using Sentinel 1 to Map African Malaria Vector Mosquito Breeding Habitats. REMOTE SENSING 2019. [DOI: 10.3390/rs11050593] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Providing timely and accurate maps of surface water is valuable for mapping malaria risk and targeting disease control interventions. Radar satellite remote sensing has the potential to provide this information but current approaches are not suitable for mapping African malarial mosquito aquatic habitats that tend to be highly dynamic, often with emergent vegetation. We present a novel approach for mapping both open and vegetated water bodies using serial Sentinel-1 imagery for Western Zambia. This region is dominated by the seasonally inundated Upper Zambezi floodplain that suffers from a number of public health challenges. The approach uses open source segmentation and machine learning (extra trees classifier), applied to training data that are automatically derived using freely available ancillary data. Refinement is implemented through a consensus approach and Otsu thresholding to eliminate false positives due to dry flat sandy areas. The results indicate a high degree of accuracy (mean overall accuracy 92% st dev 3.6) providing a tractable solution for operationally mapping water bodies in similar large river floodplain unforested environments. For the period studied, 70% of the total water extent mapped was attributed to vegetated water, highlighting the importance of mapping both open and vegetated water bodies for surface water mapping.
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26
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Eneh LK, Fillinger U, Borg Karlson AK, Kuttuva Rajarao G, Lindh J. Anopheles arabiensis oviposition site selection in response to habitat persistence and associated physicochemical parameters, bacteria and volatile profiles. MEDICAL AND VETERINARY ENTOMOLOGY 2019; 33:56-67. [PMID: 30168151 PMCID: PMC6359949 DOI: 10.1111/mve.12336] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 05/11/2018] [Accepted: 07/24/2018] [Indexed: 05/16/2023]
Abstract
A better understanding of the oviposition behaviour of malaria vectors might facilitate the development of new vector control tools. However, the factors that guide the aquatic habitat selection of gravid females are poorly understood. The present study explored the relative attractiveness of similar artificial ponds (0.8 m2 ) aged at varying lengths prior to opening in such a way that wild Anopheles arabiensis could choose between ponds that were freshly set up, or were aged 4 or 17 days old, to lay eggs. Physicochemical parameters, bacterial profile and volatile organic compounds emitted from ponds were investigated over three experimental rounds. Fresh ponds contained on average twice as many An. arabiensis instar larvae (mean 50, 95% confidence interval (CI) = 29-85) as the ponds that had aged 4 days (mean = 24, 95% CI = 14-42) and 17 days (mean = 20, 95% CI: 12-34). Fresh ponds were associated with a significantly higher turbidity combined with higher water temperature, higher nitrite levels and a lower pH and chlorophyll level than the older ponds. Round by round analyses suggested that bacteria communities differed between age groups and also that 4-heptanone, 2-ethylhexanal and an isomer of octenal were exclusively detected from the fresh ponds. These characteristics may be useful with respect to developing attract and kill strategies for malaria vector control.
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Affiliation(s)
- L K Eneh
- Chemical Ecology, Department of Chemistry, School of Engineering Science in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
| | - U Fillinger
- International Centre of Insect Physiology and Ecology, Human Health Theme, Thomas Odhiambo Campus, Mbita, Kenya
| | - A K Borg Karlson
- Chemical Ecology, Department of Chemistry, School of Engineering Science in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
| | - G Kuttuva Rajarao
- Department of Industrial Biotechnology, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH, Royal Institute of Technology, Stockholm, Sweden
| | - J Lindh
- Chemical Ecology, Department of Chemistry, School of Engineering Science in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
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27
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Defeating Fluorosis in the East African Rift Valley: Transforming the Kilimanjaro into a Rainwater Harvesting Park. SUSTAINABILITY 2018. [DOI: 10.3390/su10114194] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The high availability of fluoride in surface and groundwater in the East African Rift Valley was documented during the colonial period. Since the early 1960s, many studies have been conducted to solve the fluorosis crisis in this region. At present, no cost-effective solution to mitigate fluoride contamination is available for the large majority of the population. This situation prompted a process analysis of commonly used technologies. Results revealed that the geochemistry of fluoride is the main problem. Fluoride is very difficult to remove from the aqueous phase. Thus, eliminating the need for technical water defluoridation is an excellent way out of the fluorosis crisis. This goal can be achieved by harvesting fluoride-free rainwater. Harvested rainwater can be mixed with naturally polluted waters in calculated proportions to obtain safe drinking water (blending). This paper presents a concept to transform the Kilimanjaro Mountains into a huge rainwater harvesting park for drinking water supply for the whole East African Rift Valley. However, blended water may contain other pollutants including pathogens that are easy to treat using low-cost methods such as metallic iron based-filters (Fe0 filters). The proposed concept is transferable to other parts of the world still enduring fluoride pollution.
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28
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Paleopathological Considerations on Malaria Infection in Korea before the 20th Century. BIOMED RESEARCH INTERNATIONAL 2018; 2018:8516785. [PMID: 29854798 PMCID: PMC5966694 DOI: 10.1155/2018/8516785] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 04/01/2018] [Indexed: 12/31/2022]
Abstract
Malaria, one of the deadliest diseases in human history, still infects many people worldwide. Among the species of the genus Plasmodium, P. vivax is commonly found in temperate-zone countries including South Korea. In this article, we first review the history of malarial infection in Korea by means of studies on Joseon documents and the related scientific data on the evolutionary history of P. vivax in Asia. According to the historical records, malarial infection was not unusual in pre-20th-century Korean society. We also found that certain behaviors of the Joseon people might have affected the host-vector-pathogen relationship, which could explain why malarial infection prevalence was so high in Korea at that time. In our review of genetic studies on P. vivax, we identified substantial geographic differentiation among continents and even between neighboring countries. Based on these, we were able to formulate a strategy for future analysis of ancient Plasmodium strains in Korea.
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29
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Silva GLD, Pereira TN, Ferla NJ, Silva OSD. The impact of insecticides management linked with resistance expression in Anopheles spp. populations. CIENCIA & SAUDE COLETIVA 2018; 21:2179-88. [PMID: 27383351 DOI: 10.1590/1413-81232015217.00922015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 06/11/2015] [Indexed: 11/22/2022] Open
Abstract
The resistance of some species of Anopheles to chemical insecticides is spreading quickly throughout the world and has hindered the actions of prevention and control of malaria. The main mechanism responsible for resistance in these insects appears to be the target site known as knock-down resistance (kdr), which causes mutations in the sodium channel. Even so, many countries have made significant progress in the prevention of malaria, focusing largely on vector control through long-lasting insecticide nets (LLINs), indoor residual spraying and (IRS) of insecticides. The objective of this review is to contribute with information on the more applied insecticides for the control of the main vectors of malaria, its effects, and the different mechanisms of resistance. Currently it is necessary to look for others alternatives, e.g. biological control and products derived from plants and fungi, by using other organisms as a possible regulator of the populations of malaria vectors in critical outbreaks.
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Affiliation(s)
- Guilherme Liberato da Silva
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal do Rio Grande do Sul. R. Sarmento Leite 500, Centro Histórico. 90050-170 Porto Alegre RS Brasil.
| | - Thiago Nunes Pereira
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal do Rio Grande do Sul. R. Sarmento Leite 500, Centro Histórico. 90050-170 Porto Alegre RS Brasil.
| | - Noeli Juarez Ferla
- Laboratório de Acarologia, Museu de Ciências Naturais, Centro Universitário UNIVATES. Lajeado RS Brasil
| | - Onilda Santos da Silva
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal do Rio Grande do Sul. R. Sarmento Leite 500, Centro Histórico. 90050-170 Porto Alegre RS Brasil.
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Wondwosen B, Birgersson G, Tekie H, Torto B, Ignell R, Hill SR. Sweet attraction: sugarcane pollen-associated volatiles attract gravid Anopheles arabiensis. Malar J 2018; 17:90. [PMID: 29466989 PMCID: PMC5822481 DOI: 10.1186/s12936-018-2245-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 02/18/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Anopheles arabiensis is a key vector for the transmission of human malaria in sub-Saharan Africa. Over the past 10,000 years, humans have successfully cultivated grasses and altered the landscape, creating An. arabiensis favourable environments that contain excellent habitats for both larvae and adults. Sugarcane is the most expanding agricultural system in sub-Saharan Africa, and is linked to the increased threat of malaria in rural communities. The prolific production and wind dispersal of sugarcane pollen, together with standing pools of water, often provide, as a result of irrigation, a nutrient-rich environment for the offspring of gravid malaria mosquitoes. RESULTS In the present study, sugarcane pollen-associated volatiles from two cultivars are shown to attract gravid An. arabiensis in a still air two-port olfactometer and stimulate egg laying in an oviposition bioassay. Through combined gas chromatography and electroantennographic detection, as well as combined gas chromatography and mass spectrometric analyses, we identified the bioactive volatiles and generated a synthetic blend that reproduced the full behavioural repertoire of gravid mosquitoes in the Y-tube assay. Two subtractive odour blends, when compared with the full blend, were significantly more attractive. These three and four-component subtractive blends share the compounds (1R)-(+)-α-pinene, nonanal and benzaldehyde, of which, (1R)-(+)-α-pinene and nonanal are found in the attractive odour blends from rice plants and maize pollen. In pairwise comparisons, the rice synthetic odour blend was more attractive to gravid mosquitoes than either of the pollen blends, whereas the pollen blends did not differ in attraction. CONCLUSIONS The attraction of gravid females to sugarcane pollen volatiles demonstrated in this study, together with the previously found grass-associated volatiles, raise the potential of developing a bioactive chimeric blend to attract gravid malaria mosquitoes. This is discussed in relation to the development of novel and cost-effective vector control measures.
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Affiliation(s)
- Betelehem Wondwosen
- Department of Zoological Sciences, Addis Ababa University, Box 1176, Addis Ababa, Ethiopia
| | - Göran Birgersson
- Disease Vector Group, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Box 102, Sundsvägen 14, 230 53, Alnarp, Sweden
| | - Habte Tekie
- Department of Zoological Sciences, Addis Ababa University, Box 1176, Addis Ababa, Ethiopia
| | - Baldwyn Torto
- Behavioural and Chemical Ecology Department, International Centre of Insect Physiology and Ecology, P. O. Box 30772, Nairobi, 00100, Kenya
| | - Rickard Ignell
- Disease Vector Group, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Box 102, Sundsvägen 14, 230 53, Alnarp, Sweden
| | - Sharon R Hill
- Disease Vector Group, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Box 102, Sundsvägen 14, 230 53, Alnarp, Sweden.
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31
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Chepkemoi ST, Mararo E, Butungi H, Paredes J, Masiga D, Sinkins SP, Herren JK. Identification of Spiroplasmainsolitum symbionts in Anopheles gambiae. Wellcome Open Res 2017; 2:90. [PMID: 29152597 PMCID: PMC5668936 DOI: 10.12688/wellcomeopenres.12468.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2017] [Indexed: 12/20/2022] Open
Abstract
Background: Insect symbionts have the potential to block the transmission of vector-borne diseases by their hosts. The advancement of a symbiont-based transmission blocking strategy for malaria requires the identification and study of
Anopheles symbionts. Methods: High throughput 16S amplicon sequencing was used to profile the bacteria associated with
Anopheles gambiae sensu lato and identify potential symbionts. The polymerase chain reaction (PCR) with specific primers were subsequently used to monitor symbiont prevalence in field populations, as well as symbiont transmission patterns. Results: We report the discovery of the bacterial symbiont,
Spiroplasma, in
Anopheles gambiae in Kenya. We determine that geographically dispersed
Anopheles gambiae populations in Kenya are infected with
Spiroplasma at low prevalence levels. Molecular phylogenetics indicates that this
Anopheles gambiae associated
Spiroplasma is a member of the
insolitum clade. We demonstrate that this symbiont is stably maternally transmitted across at least two generations and does not significantly affect the fecundity or egg to adult survival of its host. Conclusions: In diverse insect species,
Spiroplasma has been found to render their host resistant to infection by pathogens. The identification of a maternally transmitted strain of
Spiroplasma in
Anopheles gambiae may therefore open new lines of investigation for the development of symbiont-based strategies for blocking malaria transmission.
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Affiliation(s)
- Sharon T Chepkemoi
- Centre for Biotechnology and Bioinformatics (CEBIB), University of Nairobi, Nairobi, Kenya.,International Centre of Insect Physiology and Ecology (ICIPE), Kasarani, Nairobi, Kenya
| | - Enock Mararo
- International Centre of Insect Physiology and Ecology (ICIPE), Kasarani, Nairobi, Kenya
| | - Hellen Butungi
- International Centre of Insect Physiology and Ecology (ICIPE), Kasarani, Nairobi, Kenya
| | - Juan Paredes
- International Centre of Insect Physiology and Ecology (ICIPE), Kasarani, Nairobi, Kenya
| | - Daniel Masiga
- International Centre of Insect Physiology and Ecology (ICIPE), Kasarani, Nairobi, Kenya
| | - Steven P Sinkins
- MRC-University of Glasgow Centre for Virus Research, Henry Wellcome Building, Glasgow, UK
| | - Jeremy K Herren
- International Centre of Insect Physiology and Ecology (ICIPE), Kasarani, Nairobi, Kenya.,MRC-University of Glasgow Centre for Virus Research, Henry Wellcome Building, Glasgow, UK
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32
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Asmare Y, Hopkins RJ, Tekie H, Hill SR, Ignell R. Grass Pollen Affects Survival and Development of Larval Anopheles arabiensis (Diptera: Culicidae). JOURNAL OF INSECT SCIENCE (ONLINE) 2017; 17:4107058. [PMID: 28922900 PMCID: PMC5597869 DOI: 10.1093/jisesa/iex067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Indexed: 05/10/2023]
Abstract
Nutrients in breeding sites are critical for the survival and development of malaria mosquitoes, having a direct impact on vectorial capacity. Yet, there is a limited understanding about the natural larval diet and its impact on the individual fitness of mosquitoes. Recent studies have shown that gravid Anopheles arabiensis Patton (Diptera: Culicidae) are attracted by and oviposit in grass-associated habitats. The pollen provided by these grasses is a potential source of nutrients for the larvae. Here, we assess the effect of Typha latifolia L. (Poales: Typhaceae), Echinochloa pyramidalis Lamarck, Pennisetum setaceum Forsskål, and Zea mays L. pollen on larval survival and rate of development in An. arabiensis under laboratory conditions. In addition, we characterize the carbon to nitrogen ratio and the size of pollen grains as a measure of diet quality. Carbon-rich pollen with a small grain size (T. latifolia and P. setaceum; 9.7 ± 0.3 × 103 and 5.5 ± 0.2 × 104 µm3, respectively) resulted in enhanced rates of development of An. arabiensis. In contrast, the larva fed on the nitrogen-rich control diet (TetraMin) was slower to develop, but demonstrated the highest larval survival. Larvae fed on carbon-rich and large-grained Z. mays pollen (4.1 ± 0.2 × 105 µm3) survived at similar levels as those fed on the control diet and also took a longer time to develop compared with larvae fed on the other pollens. While males and females did not appear to develop differently on the different pollen diets, males consistently emerged faster than their female counterparts. These results are discussed in relation to integrated vector management.
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Affiliation(s)
- Yelfwagash Asmare
- Department of Zoological Sciences, Addis Ababa University, PO. Box 1176, Addis Ababa, Ethiopia
- Department of Biological Sciences, Debre Markos University, Debre Markos, Ethiopia
| | - Richard J Hopkins
- Natural Resources Institute, University of Greenwich, London, United Kingdom
| | - Habte Tekie
- Department of Zoological Sciences, Addis Ababa University, PO. Box 1176, Addis Ababa, Ethiopia
| | - Sharon R Hill
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden, and
| | - Rickard Ignell
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden, and
- Corresponding author, e-mail:
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Mashauri FM, Manjurano A, Kinung’hi S, Martine J, Lyimo E, Kishamawe C, Ndege C, Ramsan MM, Chan A, Mwalimu CD, Changalucha J, Magesa S. Indoor residual spraying with micro-encapsulated pirimiphos-methyl (Actellic® 300CS) against malaria vectors in the Lake Victoria basin, Tanzania. PLoS One 2017; 12:e0176982. [PMID: 28489935 PMCID: PMC5425192 DOI: 10.1371/journal.pone.0176982] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 04/20/2017] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The indoor residual spraying programme for malaria vectors control was implemented in four districts of the Lake Victoria basin of Tanzania namely Ukerewe, Sengerema, Rorya andSerengeti. Entomological monitoring activities were implemented in one sentinel village in each district to evaluate the efficacy of pirimiphos-methyl 300 CS sprayed on different wall surfaces and its impact against malaria vectors post-IRS intervention. METHODS The residual decay rate of p-methyl 300 CS applied at a target dosage of 1g a.i./m2 on thesprayed wall surfaces was monitored for a period of 43 weeks post-IRSusing the WHO cone wall bioassay method. The bioassays were performed by exposing 2-5 days old unfed susceptible female Anopheles gambiae s.s. (Kisumu strain) to sprayed wall surfaces for a period of 30 minutes. In each sentinel village, mosquito collection was carried out by trained community mosquito collectors. Monthly mosquito collections were carried out from 6.00pm to 6.00am using CDC light traps and clay pot methods for indoors host seekingand outdoors resting mosquitoes respectively. Six traps (2 CDC light traps and 4 clay pots) were set per sentinel village per night for28 consecutive days in a moon. PCR and ELISA were used for mosquito species identification and sporozoite detection, respectively. RESULTS Based on the WHOPES recommendation, insecticides should have a minimum efficacy of ≥ 80% mosquito mortality at 24 hours post exposure on the sprayed wall surfaces to be considered effective. In this study, p-methyl 300 CS was demonstrated to have a long residual efficacy of 21-43 weeks post-IRS on mud, cement, painted and wood wall surfaces. Numberof anopheline mosquitoes decreased post-IRS interventions in all sentinel villages. The highest numbers ofanopheline mosquitoes were collected in November-December, 38-43 weeks post-IRS. A total of 270 female anopheline mosquitoes were analyzed by PCR; out of which 236 (87.4%) were An. gambiae s.l. and 34 (12.6%) were An. funestus group. Of the 236 An. gambiae s.l.identified 12.6% (n = 34) were An. gambiae s.s. and 68.6% (n = 162) were An. arabiensis. Ofthe 34 An. funestus group indentified 91.2% (n = 31) were An. parensis and 8.8% (n = 3) were An. rivulorum. The overall Plasmodium falciparum sporozoite rate was 0.7% (n = 2,098). CONCLUSIONS Pirimiphos-methyl 300 CS was found to be effective for IRS in the Lake Victoria basin,Tanzania. P-methyl 300 CShas a long residual efficacy on sprayed wall surfaces and therefore it is effective in controlling principal malaria vectors of An. gambiae s.l and An. funestus which rest on wall surfaces after and before feeding.
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Affiliation(s)
- Fabian M. Mashauri
- National Institute for Medical Research, Mwanza Centre, Mwanza, Tanzania
| | | | - Safari Kinung’hi
- National Institute for Medical Research, Mwanza Centre, Mwanza, Tanzania
| | - Jackline Martine
- National Institute for Medical Research, Mwanza Centre, Mwanza, Tanzania
| | - Eric Lyimo
- National Institute for Medical Research, Mwanza Centre, Mwanza, Tanzania
| | - Coleman Kishamawe
- National Institute for Medical Research, Mwanza Centre, Mwanza, Tanzania
| | - Chacha Ndege
- National Institute for Medical Research, Mwanza Centre, Mwanza, Tanzania
| | - Mahdi M. Ramsan
- Research Triangle Institute (RTI) International, Dar es salaam, Tanzania
| | - Adeline Chan
- Centers for Disease Control and Prevention, Atlanta, United States of America
| | - Charles D. Mwalimu
- National Malaria Control Program, Ministry of Health, Community Development, Gender, Elderly and Children, Dar es salaam, Tanzania
| | - John Changalucha
- National Institute for Medical Research, Mwanza Centre, Mwanza, Tanzania
| | - Stephen Magesa
- Research Triangle Institute (RTI) International, Dar es salaam, Tanzania
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Kibret S, Wilson GG, Ryder D, Tekie H, Petros B. Malaria impact of large dams at different eco-epidemiological settings in Ethiopia. Trop Med Health 2017; 45:4. [PMID: 28250711 PMCID: PMC5324293 DOI: 10.1186/s41182-017-0044-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/31/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Dams are important to ensure food security and promote economic development in sub-Saharan Africa. However, a poor understanding of the negative public health consequences from issues such as malaria could affect their intended advantages. This study aims to compare the malaria situation across elevation and proximity to dams. Such information may contribute to better understand how dams affect malaria in different eco-epidemiological settings. METHODS Larval and adult mosquitoes were collected from dam and non-dam villages around the Kesem (lowland), Koka (midland), and Koga (highland) dams in Ethiopia between October 2013 and July 2014. Determination of blood meal sources and detection of Plasmodium falciparum sporozoites was done using enzyme-linked immunosorbent assay (ELISA). Five years of monthly malaria case data (2010-2014) were also collected from health centers in the study villages. RESULTS Mean monthly malaria incidence was two- and ten-fold higher in the lowland dam village than in midland and highland dam villages, respectively. The total surface area of anopheline breeding habitats and the mean larval density was significantly higher in the lowland dam village compared with the midland and highland dam villages. Similarly, the mean monthly malaria incidence and anopheline larval density was generally higher in the dam villages than in the non-dam villages in all the three dam settings. Anopheles arabiensis, Anopheles pharoensis, and Anopheles funestus s.l. were the most common species, largely collected from lowland and midland dam villages. Larvae of these species were mainly found in reservoir shoreline puddles and irrigation canals. The mean adult anopheline density was significantly higher in the lowland dam village than in the midland and highland dam villages. The annual entomological inoculation rate (EIR) of An. arabiensis, An. funestus s.l., and An. pharoensis in the lowland dam village was 129.8, 47.8, and 33.3 infective bites per person per annum, respectively. The annual EIR of An. arabiensis and An. pharoensis was 6.3 and 3.2 times higher in the lowland dam village than in the midland dam village. CONCLUSIONS This study found that the presence of dams intensifies malaria transmission in lowland and midland ecological settings. Dam and irrigation management practices that could reduce vector abundance and malaria transmission need to be developed for these regions.
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Affiliation(s)
- Solomon Kibret
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351 Australia.,Present address: Program in Public Health, University of California, Irvine, CA 92697 USA
| | - G Glenn Wilson
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351 Australia
| | - Darren Ryder
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351 Australia
| | - Habte Tekie
- Department of Zoological Sciences, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
| | - Beyene Petros
- Department of Microbial, Cellular and Molecular Biology, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
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35
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Wondwosen B, Birgersson G, Seyoum E, Tekie H, Torto B, Fillinger U, Hill SR, Ignell R. Rice volatiles lure gravid malaria mosquitoes, Anopheles arabiensis. Sci Rep 2016; 6:37930. [PMID: 27901056 PMCID: PMC5128813 DOI: 10.1038/srep37930] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/02/2016] [Indexed: 11/09/2022] Open
Abstract
Mosquito oviposition site selection is essential for vector population dynamics and malaria epidemiology. Irrigated rice cultivations provide ideal larval habitats for malaria mosquitoes, which has resulted in increased prevalence of the malaria vector, Anopheles arabiensis, in sub-Saharan Africa. The nature and origin of the cues regulating this behaviour are only now being elucidated. We show that gravid Anopheles arabiensis are attracted and oviposit in response to the odour present in the air surrounding rice. Furthermore, we identify a synthetic rice odour blend, using electrophysiological and chemical analyses, which elicits attraction and oviposition in laboratory assays, as well as attraction of free-flying gravid mosquitoes under semi-field conditions. This research highlights the intimate link between malaria vectors and agriculture. The identified volatile cues provide important substrates for the development of novel and cost-effective control measures that target female malaria mosquitoes, irrespective of indoor or outdoor feeding and resting patterns.
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Affiliation(s)
- Betelehem Wondwosen
- Department of Zoological Sciences, Addis Ababa University, P. O. Box1176, Addis Ababa, Ethiopia.,Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P. O. Box 102, Sundsvägen 14, 230 53 Alnarp, Sweden.,Behavioural and Chemical Ecology Department, International Centre of Insect Physiology and Ecology, P. O. Box 30772, Nairobi 00100, Kenya
| | - Göran Birgersson
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P. O. Box 102, Sundsvägen 14, 230 53 Alnarp, Sweden
| | - Emiru Seyoum
- Department of Zoological Sciences, Addis Ababa University, P. O. Box1176, Addis Ababa, Ethiopia
| | - Habte Tekie
- Department of Zoological Sciences, Addis Ababa University, P. O. Box1176, Addis Ababa, Ethiopia
| | - Baldwyn Torto
- Behavioural and Chemical Ecology Department, International Centre of Insect Physiology and Ecology, P. O. Box 30772, Nairobi 00100, Kenya
| | - Ulrike Fillinger
- Behavioural and Chemical Ecology Department, International Centre of Insect Physiology and Ecology, P. O. Box 30772, Nairobi 00100, Kenya.,Disease Control Department, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Sharon R Hill
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P. O. Box 102, Sundsvägen 14, 230 53 Alnarp, Sweden
| | - Rickard Ignell
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P. O. Box 102, Sundsvägen 14, 230 53 Alnarp, Sweden
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Kweka EJ, Kimaro EE, Munga S. Effect of Deforestation and Land Use Changes on Mosquito Productivity and Development in Western Kenya Highlands: Implication for Malaria Risk. Front Public Health 2016; 4:238. [PMID: 27833907 PMCID: PMC5080343 DOI: 10.3389/fpubh.2016.00238] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 10/12/2016] [Indexed: 11/30/2022] Open
Abstract
Background African highlands were known to be free of malaria for the past 50 years. However, the ever growing human population in the highlands of Africa has led to the deforestation and land coverage changes to create space for more land for cultivation, grazing, and house construction materials needs. This has lead to the creation of suitable breeding habitats, which are in open places. Decrease of canopy and forest cover has led to increased temperature both in outdoors and indoors in deforested areas. This increased temperature has resulted in the shortening of developmental stages of aquatic stages of mosquitoes and sporogony development in adult mosquitoes. Method Assessment of the effects of deforestation and land coverage changes (decrease), which leads to temperature changes and subsequently increases survivorship of adults and sporogony development in adult mosquitoes’ body was gathered from previous data collected from 2003 to 2012 using different analysis techniques. Habitats productivity, species dynamics and abundance, mosquitoes feeding rates, and sporogony development are presented in relation to temperature changes. Results The effects of temperature rise due to land cover changes in highlands of western Kenya on larval developmental rates, adult sporogony developments, and malaria risk in human population were derived. Vector species dynamics and abundance in relation to land use changes have been found to change with time. Conclusion This study found that, land cover changes is a key driver for the temperature rise in African highlands and increases the rate of malaria vectors Anopheles gambiae ssp., An. Funestus, and An. arabiensis colonizing the highlands. It has also significantly enhanced sporogony development rate and adult vector survival and therefore the risk of malaria transmission in the highlands.
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Affiliation(s)
- Eliningaya J Kweka
- Mosquito Section, Division of Livestock and Human Diseases Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania; Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Epiphania E Kimaro
- Mosquito Section, Division of Livestock and Human Diseases Vector Control, Tropical Pesticides Research Institute , Arusha , Tanzania
| | - Stephen Munga
- Centre for Global Health Research, Kenya Medical Research Institute , Kisumu , Kenya
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Villarreal-Treviño C, Penilla-Navarro RP, Vázquez-Martínez MG, Moo-Llanes DA, Ríos-Delgado JC, Fernández-Salas I, Rodríguez AD. Larval habitat characterization of Anopheles darlingi from its northernmost geographical distribution in Chiapas, Mexico. Malar J 2015; 14:517. [PMID: 26693816 PMCID: PMC4688970 DOI: 10.1186/s12936-015-1037-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 12/04/2015] [Indexed: 12/02/2022] Open
Abstract
Background Anopheles darlingi is considered the most efficient malaria vector in the Neotropical region. In Mexico, its role as an incriminated vector of Plasmodium has not been confirmed in the Lacandon forest. Similarly, knowledge about bionomic and larval ecology is scarce. The study aim was to identify and describe the larval habitats of An. darlingi in Chiapas, México. Methods Standard larval collections were performed in the Lacandon forest region and in the Soconusco region of southern Chiapas from January 2010 to April 2014, including dry and rainy seasons. Mean larval density of An. darlingi was estimated according to hydrological types, and associations between the presence of An. darlingi and environmental factors including ecological parameters and geographic positions were statistically analysed. Results One hundred and twelve aquatic habitats were analysed, 80 from the Lacandon forest region and 32 from the Soconusco region; 94.64 % of these sites presented anopheline larvae. In total, 10,977 larvae belonging to 11 Anopheles species were collected. The 19 (out of 112) larval habitats positive to An. darlingi were: rain puddles (26.32 %), ground pools (21.05 %), ponds (15.79 %), ditches (15.79 %), river margins (10.53 %) and streams (10.53 %). Overall, the average (±SD) larval density was 6.60 ± 2.41 larvae per dip. Multiple logistic regression analysis showed that temporary habitats, green algae presence and stagnant water were associated with An. darlingi larval presence. The positive habitats were found in the Lacandon forest region during the rainy season (May–September). No specimens were found in the Soconusco region of the coastal plain of Chiapas. Conclusion The mosquito An. darlingi larval habitats were found in different hydrological types. The habitat stability, presence of algae and water current were the main factors for An. darlingi larval occurrence. The information on the characteristics of the larval habitats of An. darlingi will be useful in sustainable programmes for malaria control in the Lacandon forest region, Chiapas. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-1037-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Cuauhtémoc Villarreal-Treviño
- Centro Regional de Investigación en Salud Pública/Instituto Nacional de Salud Pública (CRISP/INSP), 19 Poniente y 4ta Avenida Norte, C.P. 30700, Tapachula, Chiapas, Mexico.
| | - R Patricia Penilla-Navarro
- Centro Regional de Investigación en Salud Pública/Instituto Nacional de Salud Pública (CRISP/INSP), 19 Poniente y 4ta Avenida Norte, C.P. 30700, Tapachula, Chiapas, Mexico.
| | - M Guadalupe Vázquez-Martínez
- Centro Regional de Investigación en Salud Pública/Instituto Nacional de Salud Pública (CRISP/INSP), 19 Poniente y 4ta Avenida Norte, C.P. 30700, Tapachula, Chiapas, Mexico.
| | - David A Moo-Llanes
- Centro Regional de Investigación en Salud Pública/Instituto Nacional de Salud Pública (CRISP/INSP), 19 Poniente y 4ta Avenida Norte, C.P. 30700, Tapachula, Chiapas, Mexico.
| | - Jana C Ríos-Delgado
- Centro Regional de Investigación en Salud Pública/Instituto Nacional de Salud Pública (CRISP/INSP), 19 Poniente y 4ta Avenida Norte, C.P. 30700, Tapachula, Chiapas, Mexico.
| | - Ildefonso Fernández-Salas
- Centro Regional de Investigación en Salud Pública/Instituto Nacional de Salud Pública (CRISP/INSP), 19 Poniente y 4ta Avenida Norte, C.P. 30700, Tapachula, Chiapas, Mexico.
| | - Américo D Rodríguez
- Centro Regional de Investigación en Salud Pública/Instituto Nacional de Salud Pública (CRISP/INSP), 19 Poniente y 4ta Avenida Norte, C.P. 30700, Tapachula, Chiapas, Mexico.
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Ngom EHM, Faye ND, Talla C, Ndiaye EH, Ndione JA, Faye O, Ba Y, Diallo M, Dia I. Anopheles arabiensis seasonal densities and infection rates in relation to landscape classes and climatic parameters in a Sahelian area of Senegal. BMC Infect Dis 2014; 14:711. [PMID: 25526645 PMCID: PMC4279681 DOI: 10.1186/s12879-014-0711-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 12/11/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The influence of environmental and climatic factors on malaria vector bionomics and transmission is an important topic in the context of climatic change particularly at macro-geographical level. Sahelian areas could be particularly affected due to heterogeneous features including high inter-annual variability in rainfall and others associated parameters. Therefore, baseline information on the impact of environmental and climatic factors on malaria transmission at micro-geographical level is required for vector risk management and implementation of control strategies. METHODS Malaria vectors were collected indoors by pyrethrum spray catches in 14 villages belonging to 4 different landscape classes (wooded savanna, shrubby savanna, bare soils and steppe) in the sylvo-pastoral area of Senegal. Plasmodium falciparum infection rates were determined using an indirect enzyme-linked immunosorbent assay (ELISA). RESULTS An. arabiensis was the predominant species in all landscape classes and was the only species collected at the end of the rainy season excepted in villages located in bare soils where it cohabited with An. coluzzii. Mean temperature and relative humidity showed similar variations in all the landscape classes covered whereas rainfall was more heterogeneous in terms of pattern, frequency and amount. The mean densities of An. arabiensis displayed high seasonal differences with peaks observed in August or September. A positive non-significant correlation was observed between An. arabiensis densities for rainfall and humidity whereas a negative non-significant correlation was reported for temperature. Plasmodium falciparum-infected mosquitoes were detected only in wooded savanna and bare soils villages. CONCLUSIONS These observations suggest key roles played by landscape classes and rainfall in malaria vector densities, infection rates and malaria transmission that could be more pronounced in villages situated in wooded savanna and bare soils. Due to the close relationship between environmental and meteorological parameters in this Sahelian region, additional studies on the impact of these parameters are required to further ascertain their association with entomological parameters involved in malaria transmission. From the public health point of view, such information could be useful for human population settlements as well as for monitoring and modelling purposes giving early warning system for implementation of interventions in these unstable transmission zones.
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Affiliation(s)
- El Hadji Malick Ngom
- Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
- Université Cheikh Anta Diop de Dakar, Dakar, Sénégal.
| | | | - Cheikh Talla
- Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
- Université Gaston Berger, Saint-Louis, Sénégal.
| | - El Hadji Ndiaye
- Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
- Université Cheikh Anta Diop de Dakar, Dakar, Sénégal.
| | | | - Ousmane Faye
- Université Cheikh Anta Diop de Dakar, Dakar, Sénégal.
| | - Yamar Ba
- Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Mawlouth Diallo
- Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Ibrahima Dia
- Unité d'entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
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Kibret S, Wilson GG, Tekie H, Petros B. Increased malaria transmission around irrigation schemes in Ethiopia and the potential of canal water management for malaria vector control. Malar J 2014; 13:360. [PMID: 25218697 PMCID: PMC4182787 DOI: 10.1186/1475-2875-13-360] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 09/11/2014] [Indexed: 12/03/2022] Open
Abstract
Background Irrigation schemes have been blamed for the increase in malaria in many parts of sub-Saharan Africa. However, proper water management could help mitigate malaria around irrigation schemes in this region. This study investigates the link between irrigation and malaria in Central Ethiopia. Methods Larval and adult mosquitoes were collected fortnightly between November 2009 and October 2010 from two irrigated and two non-irrigated (control) villages in the Ziway area, Central Ethiopia. Daily canal water releases were recorded during the study period and bi-weekly correlation analysis was done to determine relationships between canal water releases and larval/adult vector densities. Blood meal sources (bovine vs human) and malaria sporozoite infection were tested using enzyme-linked immunosorbent assay (ELISA). Monthly malaria data were also collected from central health centre of the study villages. Results Monthly malaria incidence was over six-fold higher in the irrigated villages than the non-irrigated villages. The number of anopheline breeding habitats was 3.6 times higher in the irrigated villages than the non-irrigated villages and the most common Anopheles mosquito breeding habitats were waterlogged field puddles, leakage pools from irrigation canals and poorly functioning irrigation canals. Larval and adult anopheline densities were seven- and nine-fold higher in the irrigated villages than in the non-irrigated villages, respectively, during the study period. Anopheles arabiensis was the predominant species in the study area. Plasmodium falciparum sporozoite rates of An. arabiensis and Anopheles pharoensis were significantly higher in the irrigated villages than the non-irrigated villages. The annual entomological inoculation rate (EIR) calculated for the irrigated and non-irrigated villages were 34.8 and 0.25 P. falciparum infective bites per person per year, respectively. A strong positive correlation was found between bi-weekly anopheline larval density and canal water releases. Similarly, there was a strong positive correlation between bi-weekly vector density and canal water releases lagged by two weeks. Furthermore, monthly malaria incidence was strongly correlated with monthly vector density lagged by a month in the irrigated villages. Conclusion The present study revealed that the irrigation schemes resulted in intensified malaria transmission due to poor canal water management. Proper canal water management could reduce vector abundance and malaria transmission in the irrigated villages.
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Affiliation(s)
- Solomon Kibret
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale NSW 2351, Australia.
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Vanlalruia K, Senthilkumar N, Gurusubramanian G. Diversity and abundance of mosquito species in relation to their larval habitats in Mizoram, North Eastern Himalayan region. Acta Trop 2014; 137:1-18. [PMID: 24795213 DOI: 10.1016/j.actatropica.2014.04.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 04/16/2014] [Accepted: 04/22/2014] [Indexed: 11/17/2022]
Abstract
The abundance, richness and diversity of anopheline and culicid mosquitoes associated with their habitats, season, and physico-chemical quality of water were surveyed along six districts of Mizoram, North Eastern Himalayan region. The productivity of permanent and temporary habitat types was quantified by carrying out weekly larval sampling using a standard dipping method for a period of three years. Diversity was estimated using the Shannon index (H'), Evenness index (Heve), similarity measures cluster analysis and MANOVA. In total, 5 genera and 20 species of mosquitoes were identified: Culex quinquefasciatus, Anopheles barbirostris and Anopheles vagus were the most abundant and widely-distributed species, representing 39.71%, 29.39% and 14.52% of total mosquito individuals sampled, respectively. Anopheles sp. diversity was lowest in Lunglei district (H'=0.48) and highest in Aizawl (H'=2.03), whereas Culex sp. diversity was lowest in Lawngtlai (H'=0.38), and highest in Aizawl (H'=2.99) and Kolasib (H'=2.13). This represents the first update on the diversity and geographic distribution of the mosquitoes of Mizoram. Mosquito larvae were present in both temporary and permanent habitats suitable for breeding with monthly variations dependent on rainfall intensity, temperature, humidity and location. Early instars were more abundant significantly (P<0.0001) than late instars among the habitat types in all study sites. The productivity of mosquito larvae was significantly (P<0.0001) higher in ponds especially in permanent than semi-permanent and temporary. Weekly rainfall intensity led to an increase or decrease in anopheline and culicid larval abundance depending on the location. Mosquito diversity was highest in monsoon season (July-September) and lowest in January-March. A. barbirostris, A. vagus and C. quinquefasciatus appear the most likely habitat generalist as it demonstrates both widespread distribution. Abundance and diversity of culicine and anopheline larvae were strongly associated (MANOVA) with pH, temperature, dissolved oxygen, alkalinity, phosphates and chlorides concentration of water. This information will be essential for designing and implementing mosquito larval control programs.
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Ouattara AF, Dagnogo M, Constant EAV, Koné M, Raso G, Tanner M, Olliaro PL, Utzinger J, Koudou BG. Transmission of malaria in relation to distribution and coverage of long-lasting insecticidal nets in central Côte d'Ivoire. Malar J 2014; 13:109. [PMID: 24645751 PMCID: PMC4000051 DOI: 10.1186/1475-2875-13-109] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 03/13/2014] [Indexed: 11/23/2022] Open
Abstract
Background The use of long-lasting insecticidal nets (LLINs) is an effective malaria control strategy. However, there are challenges to achieve high coverage, such as distribution sustainability, and coverage keep-up. This study assessed the effect of LLINs coverage and contextual factors on entomological indicators of malaria in rural Côte d’Ivoire. Methods The study was carried out between July 2009 and May 2012 in three villages (Bozi, N’Dakonankro and Yoho) of central Côte d’Ivoire. In Bozi and Yoho, LLINs were distributed free of charge by the national malaria control programme in 2008. In Bozi, an additional distribution was carried out in May 2011. No specific interventions were done in N’Dakonankro. Entomological surveys were conducted in July 2009 and July 2010 (baseline), and in August and November 2011 and in February 2012. Frequency of circumsporozoite protein was determined using an enzyme-linked immunosorbent assay. Regression models were employed to assess the impact of LLINs and changing patterns of irrigated rice farming on entomological parameters, and to determine associations with LLINs coverage and other contextual factors. Results In Bozi, high proportion of LLIN usage was observed (95-100%). After six months, 95% of LLINs were washed at least once and 79% were washed up to three times within one year. Anopheles gambiae was the predominant malaria vector (66.6% of all mosquitoes caught). From 2009 to 2012, in N’Dakonankro, the mean annual entomological inoculation rate (EIR) increased significantly from 116.8 infectious bites/human/year (ib/h/y) to 408.8 ib/h/y, while in the intervention villages, the EIR decreased significantly from 514.6 ib/h/y to 62.0 ib/h/y (Bozi) and from 83.9 ib/h/y to 25.5 ib/h/y (Yoho). The risk of an infectious bite over the three-year period was significantly lower in the intervention villages compared to the control village (p <0.001). Conclusion High coverage and sensitization of households to use LLINs through regular visits (particularly in Bozi) and abandoning irrigated rice farming (in Yoho) resulted in highly significant reductions of EIR. The national malaria control programme should consider household sensitization and education campaigns and other contextual factors to maximize the benefit of LLINs.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Benjamin G Koudou
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire.
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Hardy AJ, Gamarra JGP, Cross DE, Macklin MG, Smith MW, Kihonda J, Killeen GF, Ling’ala GN, Thomas CJ. Habitat hydrology and geomorphology control the distribution of malaria vector larvae in rural Africa. PLoS One 2013; 8:e81931. [PMID: 24312606 PMCID: PMC3849348 DOI: 10.1371/journal.pone.0081931] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 10/18/2013] [Indexed: 11/24/2022] Open
Abstract
Background Larval source management is a promising component of integrated malaria control and elimination. This requires development of a framework to target productive locations through process-based understanding of habitat hydrology and geomorphology. Methods We conducted the first catchment scale study of fine resolution spatial and temporal variation in Anopheles habitat and productivity in relation to rainfall, hydrology and geomorphology for a high malaria transmission area of Tanzania. Results Monthly aggregates of rainfall, river stage and water table were not significantly related to the abundance of vector larvae. However, these metrics showed strong explanatory power to predict mosquito larval abundances after stratification by water body type, with a clear seasonal trend for each, defined on the basis of its geomorphological setting and origin. Conclusion Hydrological and geomorphological processes governing the availability and productivity of Anopheles breeding habitat need to be understood at the local scale for which larval source management is implemented in order to effectively target larval source interventions. Mapping and monitoring these processes is a well-established practice providing a tractable way forward for developing important malaria management tools.
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Affiliation(s)
- Andrew J. Hardy
- Institute of Geography & Earth Sciences, Aberystwyth University, Aberystwyth, United Kingdom
- Biomedical and Environmental Sciences Thematic Group, Ifakara Health Institute, Ifakara, Tanzania
| | - Javier G. P. Gamarra
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom
| | - Dónall E. Cross
- Biomedical and Environmental Sciences Thematic Group, Ifakara Health Institute, Ifakara, Tanzania
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom
| | - Mark G. Macklin
- Institute of Geography & Earth Sciences, Aberystwyth University, Aberystwyth, United Kingdom
| | - Mark W. Smith
- School of Geography, University of Leeds, Leeds, United Kingdom
| | - Japhet Kihonda
- Biomedical and Environmental Sciences Thematic Group, Ifakara Health Institute, Ifakara, Tanzania
| | - Gerry F. Killeen
- Biomedical and Environmental Sciences Thematic Group, Ifakara Health Institute, Ifakara, Tanzania
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - George N. Ling’ala
- Biomedical and Environmental Sciences Thematic Group, Ifakara Health Institute, Ifakara, Tanzania
| | - Chris J. Thomas
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom
- * E-mail:
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Muturi EJ, Mwangangi JM, Beier JC, Blackshear M, Wauna J, Sang R, Mukabana WR. Ecology and behavior of Anopheles arabiensis in relation to agricultural practices in central Kenya. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2013; 29:222-230. [PMID: 24199496 DOI: 10.2987/13-6328r.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Ecological changes associated with anthropogenic ecosystem disturbances can influence human risk of exposure to malaria and other vector-borne infectious diseases. This study in Mwea, Kenya, investigated the pattern of insecticide use in irrigated and nonirrigated agroecosystems and association with the density, survival, and blood-feeding behavior of the malaria vector Anopheles arabiensis. The parity rates of adult An. arabiensis from randomly selected houses were determined by examining their ovaries for tracheal distension, and polymerase chain reaction was used to identify the host blood meals. In addition, structured questionnaires were used to generate data on insecticide use. Anopheles arabiensis densities were highest in irrigated rice agroecosystems, intermediate in irrigated French beans agroecosystems, and lowest in the nonirrigated agroecosystem. Anopheles arabiensis adult survivorship was significantly lower in irrigated rice agroecosystems than in irrigated French beans agroecosystems. The human blood index (HBI) was significantly higher in the nonirrigated agroecosystem compared to irrigated agroecosystems. Moreover, there was marked variation in HBI among villages in irrigated agroecosystems with significantly lower HBI in Kangichiri and Mathangauta compared to Kiuria, Karima, and Kangai. The proportion of mosquitoes with mixed blood meals varied among villages ranging from 0.25 in Kangichiri to 0.83 in Kiuria. Sumithion, dimethoate, and alpha cypermethrin were the most commonly used insecticides. The 1st was used mostly in irrigated rice agroecosystems, and the last 2 were used mostly in irrigated French beans agroecosystems. These findings indicate that agricultural practices may influence the ecology and behavior of malaria vectors and ultimately the risk of malaria transmission.
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Affiliation(s)
- Ephantus J Muturi
- Illinois Natural History Survey, University of Illinois, Champaign, IL 61820, USA
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Oluwagbemi OO, Fornadel CM, Adebiyi EF, Norris DE, Rasgon JL. ANOSPEX: a stochastic, spatially explicit model for studying Anopheles metapopulation dynamics. PLoS One 2013; 8:e68040. [PMID: 23861847 PMCID: PMC3704604 DOI: 10.1371/journal.pone.0068040] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 05/29/2013] [Indexed: 01/23/2023] Open
Abstract
Anopheles mosquitoes transmit malaria, a major public health problem among many African countries. One of the most effective methods to control malaria is by controlling the Anopheles mosquito vectors that transmit the parasites. Mathematical models have both predictive and explorative utility to investigate the pros and cons of different malaria control strategies. We have developed a C++ based, stochastic spatially explicit model (ANOSPEX; Ano pheles Spatially-Explicit) to simulate Anopheles metapopulation dynamics. The model is biologically rich, parameterized by field data, and driven by field-collected weather data from Macha, Zambia. To preliminarily validate ANOSPEX, simulation results were compared to field mosquito collection data from Macha; simulated and observed dynamics were similar. The ANOSPEX model will be useful in a predictive and exploratory manner to develop, evaluate and implement traditional and novel strategies to control malaria, and for understanding the environmental forces driving Anopheles population dynamics.
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Affiliation(s)
- Olugbenga O. Oluwagbemi
- W. Harry Feinstone Department of Molecular Microbiology and Immunology and the Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- Department of Computer and Information Sciences, College of Science and Technology, School of Natural and Applied Sciences, Covenant University, Ota, Ogun State, Nigeria
| | - Christen M. Fornadel
- W. Harry Feinstone Department of Molecular Microbiology and Immunology and the Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Ezekiel F. Adebiyi
- Department of Computer and Information Sciences, College of Science and Technology, School of Natural and Applied Sciences, Covenant University, Ota, Ogun State, Nigeria
| | - Douglas E. Norris
- W. Harry Feinstone Department of Molecular Microbiology and Immunology and the Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Jason L. Rasgon
- The Department of Entomology, Center for Infectious Disease Dynamics and Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
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Mwangangi JM, Muturi EJ, Muriu SM, Nzovu J, Midega JT, Mbogo C. The role of Anopheles arabiensis and Anopheles coustani in indoor and outdoor malaria transmission in Taveta District, Kenya. Parasit Vectors 2013; 6:114. [PMID: 23601146 PMCID: PMC3652741 DOI: 10.1186/1756-3305-6-114] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 04/17/2013] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The scaling up of malaria vector control efforts in Africa has resulted in changing the malaria vectorial systems across different ecological settings. In view of the ongoing trends in vector population dynamics, abundance, species composition and parasite infectiousness, there is a need to understand vector distribution and their contribution to malaria transmission to facilitate future planning of control strategies. We studied indoor and outdoor malaria transmission dynamics and vector population variability of Anopheles mosquitoes in Taveta district along the Kenyan Coast. METHODS Anopheles mosquitoes were collected indoors and outdoors in 4 ecologically different villages using CDC light traps (both indoor and outdoor) and aspiration method (day resting indoors; DRI) methods. Mosquitoes were examined for infection with P. falciparum sporozoites and blood feeding preferences using enzyme linked immunosorbent assay (ELISA). The An. gambiae and An. funestus complexes were identified by PCR technique to determine the sibling species composition. RESULTS A total of 4,004 Anopheles mosquitoes were collected consisting of 34.9%% (n = 1,397) An. gambiae s.1., 28.1% (n = 1,124) An. funestus s.l., 33.5% (n = 1,340) An. coustani and 3.6% (n = 143) An. pharoensis. A total of 14,654 culicine mosquitoes were collected, mainly Cx. quinquefasciatus. Of the total Anopheles collected, 3,729 were tested for P. falciparum sporozoite infection. The sporozoite transmission was found to be occurring both indoors and outdoors. The overall sporozoite infectivity was 0.68% (n = 2,486) indoors and 1.29% (n = 1,243) outdoors. Indoor and outdoor sporozoite infectivity and the vectorial systems varied across the 4 ecological villages. Entomological inoculation rates for the 4 villages indicate that there was site-to-site variation. In the 4 villages, Mwarusa had the highest EIRs with An. arabiensis, An. funestus and An. coustani contributing to 23.91, 11.96 and 23.91 infectious bites per person per year ib/p/year respectively. In Kiwalwa and Njoro outdoor EIR was significantly higher than indoors. CONCLUSIONS This study shows that malaria transmission is occurring both indoors and outdoors. The main vectors are An. arabiensis, An. funestus and An. coustani indoors while An. coustani is playing a major role in outdoor transmission. Effective malaria control programmes, should therefore include tools that target both indoor and outdoor transmission.
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Affiliation(s)
- Joseph M Mwangangi
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research Coast, P,O, Box 42880108, Kilifi, Kenya.
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Basurko C, Demattei C, Han-Sze R, Grenier C, Joubert M, Nacher M, Carme B. Deforestation, agriculture and farm jobs: a good recipe for Plasmodium vivax in French Guiana. Malar J 2013; 12:90. [PMID: 23497050 PMCID: PMC3602177 DOI: 10.1186/1475-2875-12-90] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 02/27/2013] [Indexed: 11/24/2022] Open
Abstract
Background In a malaria-endemic area the distribution of patients is neither constant in time nor homogeneous in space. The WHO recommends the stratification of malaria risk on a fine geographical scale. In the village of Cacao in French Guiana, the study of the spatial and temporal distribution of malaria cases, during an epidemic, allowed a better understanding of the environmental factors promoting malaria transmission. Methods A dynamic cohort of 839 persons living in 176 households (only people residing permanently in the village) was constituted between January1st, 2002 and December 31st, 2007. The information about the number of inhabitants per household, the number of confirmed cases of Plasmodium vivax and house GPS coordinates were collected to search for spatial or temporal clustering using Kurlldorff’s statistical method. Results Of the 839 persons living permanently in the village of Cacao, 359 persons presented at least one vivax malaria episode between 2002 and 2007. Five temporal clusters and four spatial clusters were identified during the study period. In all temporal clusters, April was included. Two spatial clusters were localized at the north of the village near the Comté River and two others localized close to orchards. Conclusion The spatial heterogeneity of malaria in the village may have been influenced by environmental disturbances due to local agricultural policies: deforestation, cultures of fresh produce, or drainage of water for agriculture. This study allowed generating behavioural, entomological, or environmental hypotheses that could be useful to improve prevention campaigns.
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Affiliation(s)
- Célia Basurko
- Centre d'Investigation Clinique Epidémiologie Clinique Antilles Guyane CIC-EC CIE 802, Centre Hospitalier de Cayenne, rue des Flamboyants, BP 6006, Cayenne, F- 97306, French Guiana.
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Kweka EJ, Zhou G, Munga S, Lee MC, Atieli HE, Nyindo M, Githeko AK, Yan G. Anopheline larval habitats seasonality and species distribution: a prerequisite for effective targeted larval habitats control programmes. PLoS One 2012; 7:e52084. [PMID: 23272215 PMCID: PMC3525533 DOI: 10.1371/journal.pone.0052084] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 11/15/2012] [Indexed: 11/21/2022] Open
Abstract
Background Larval control is of paramount importance in the reduction of malaria vector abundance and subsequent disease transmission reduction. Understanding larval habitat succession and its ecology in different land use managements and cropping systems can give an insight for effective larval source management practices. This study investigated larval habitat succession and ecological parameters which influence larval abundance in malaria epidemic prone areas of western Kenya. Methods and Findings A total of 51 aquatic habitats positive for anopheline larvae were surveyed and visited once a week for a period of 85 weeks in succession. Habitats were selected and identified. Mosquito larval species, physico-chemical parameters, habitat size, grass cover, crop cycle and distance to nearest house were recorded. Polymerase chain reaction revealed that An. gambiae s.l was the most dominant vector species comprised of An.gambiae s.s (77.60%) and An.arabiensis (18.34%), the remaining 4.06% had no amplification by polymerase chain reaction. Physico-chemical parameters and habitat size significantly influenced abundance of An. gambiae s.s (P = 0.024) and An. arabiensis (P = 0.002) larvae. Further, larval species abundance was influenced by crop cycle (P≤0.001), grass cover (P≤0.001), while distance to nearest houses significantly influenced the abundance of mosquito species larvae (r = 0.920;P≤0.001). The number of predator species influenced mosquito larval abundance in different habitat types. Crop weeding significantly influenced with the abundance of An.gambiae s.l (P≤0.001) when preceded with fertilizer application. Significantly higher anopheline larval abundance was recorded in habitats in pasture compared to farmland (P = 0.002). When habitat stability and habitat types were considered, hoof print were the most productive followed by disused goldmines. Conclusion These findings suggest that implementation of effective larval control programme should be targeted with larval habitats succession information when larval habitats are fewer and manageable. Crop cycles and distance from habitats to household should be considered as effective information in planning larval control.
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Affiliation(s)
- Eliningaya J Kweka
- Climate and Human Health Research Unit, Kenya Medical Research Institute, Kisumu, Kenya.
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Charlwood JD, Tomás EV, Egyir-Yawson A, Kampango AA, Pitts RJ. Feeding frequency and survival of Anopheles gambiae in a rice-growing area in Ghana. MEDICAL AND VETERINARY ENTOMOLOGY 2012; 26:263-270. [PMID: 22092441 DOI: 10.1111/j.1365-2915.2011.00987.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Mortality rates, determined by dissection, of predominantly M form female Anopheles gambiae (Diptera: Culicidae) were estimated. Mosquitoes were collected in tent traps and light traps in an irrigation project village in Ghana in June and July 2010, when much of the area was flooded. Both M and S form larvae were collected from rice fields (74 of 80 specimens were M form). Adults were collected in equal proportions from the two traps (90 of 107 specimens from the light trap and 106 of 116 specimens from the tent trap were M form). During the study, collection numbers rose from 105 to 972 per night. A total of 1787 of the 15 431 An. gambiae collected were dissected. Of these, 953 (53%) were found to have taken their first bloodmeal, either as virgins or following mating. The age profiles of mosquitoes collected alive and dead, respectively, were similar. Eighteen of 2933 (0.61 ± 0.49%) specimens were found to be positive for sporozoites in an enzyme-linked immunosorbent assay (ELISA). Lagged cross correlations among the different age groups implied that the mosquitoes fed on days 2 and 4 following emergence prior to oviposition and every 2.65 ± 0.17 days thereafter. The best model to describe the observed population patterns implied a daily mortality of 84%. The results are discussed in relation to possible mosquito control measures for the village.
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Affiliation(s)
- J D Charlwood
- MOZDAN (Mozambican-Danish Rural Malaria Initiative), Morrumbene, Mozambique.
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Sanchez-Ribas J, Parra-Henao G, Guimarães AÉ. Impact of dams and irrigation schemes in Anopheline (Diptera: Culicidae) bionomics and malaria epidemiology. Rev Inst Med Trop Sao Paulo 2012; 54:179-91. [DOI: 10.1590/s0036-46652012000400001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 04/13/2012] [Indexed: 11/21/2022] Open
Abstract
Irrigation schemes and dams have posed a great concern on public health systems of several countries, mainly in the tropics. The focus of the present review is to elucidate the different ways how these human interventions may have an effect on population dynamics of anopheline mosquitoes and hence, how local malaria transmission patterns may be changed. We discuss different studies within the three main tropical and sub-tropical regions (namely Africa, Asia and the Pacific and the Americas). Factors such as pre-human impact malaria epidemiological patterns, control measures, demographic movements, human behaviour and local Anopheles bionomics would determine if the implementation of an irrigation scheme or a dam will have negative effects on human health. Some examples of successful implementation of control measures in such settings are presented. The use of Geographic Information System as a powerful tool to assist on the study and control of malaria in these scenarios is also highlighted.
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Meyrowitsch DW, Pedersen EM, Alifrangis M, Scheike TH, Malecela MN, Magesa SM, Derua YA, Rwegoshora RT, Michael E, Simonsen PE. Is the current decline in malaria burden in sub-Saharan Africa due to a decrease in vector population? Malar J 2011; 10:188. [PMID: 21752273 PMCID: PMC3160426 DOI: 10.1186/1475-2875-10-188] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 07/13/2011] [Indexed: 12/01/2022] Open
Abstract
Background In sub-Saharan Africa (SSA), malaria caused by Plasmodium falciparum has historically been a major contributor to morbidity and mortality. Recent reports indicate a pronounced decline in infection and disease rates which are commonly ascribed to large-scale bed net programmes and improved case management. However, the decline has also occurred in areas with limited or no intervention. The present study assessed temporal changes in Anopheline populations in two highly malaria-endemic communities of NE Tanzania during the period 1998-2009. Methods Between 1998 and 2001 (1st period) and between 2003 and 2009 (2nd period), mosquitoes were collected weekly in 50 households using CDC light traps. Data on rainfall were obtained from the nearby climate station and were used to analyze the association between monthly rainfall and malaria mosquito populations. Results The average number of Anopheles gambiae and Anopheles funestus per trap decreased by 76.8% and 55.3%, respectively over the 1st period, and by 99.7% and 99.8% over the 2nd period. During the last year of sampling (2009), the use of 2368 traps produced a total of only 14 Anopheline mosquitoes. With the exception of the decline in An. gambiae during the 1st period, the results did not reveal any statistical association between mean trend in monthly rainfall and declining malaria vector populations. Conclusion A longitudinal decline in the density of malaria mosquito vectors was seen during both study periods despite the absence of organized vector control. Part of the decline could be associated with changes in the pattern of monthly rainfall, but other factors may also contribute to the dramatic downward trend. A similar decline in malaria vector densities could contribute to the decrease in levels of malaria infection reported from many parts of SSA.
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Affiliation(s)
- Dan W Meyrowitsch
- Section of Health Services Research, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5B, DK-1014, Copenhagen K, Denmark.
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