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Aschale Y, Getachew A, Yewhalaw D, De Cristofaro A, Sciarretta A, Atenafu G. Systematic review of sporozoite infection rate of Anopheles mosquitoes in Ethiopia, 2001-2021. Parasit Vectors 2023; 16:437. [PMID: 38008761 PMCID: PMC10680292 DOI: 10.1186/s13071-023-06054-y] [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: 04/09/2023] [Accepted: 11/13/2023] [Indexed: 11/28/2023] Open
Abstract
BACKGROUND Adult mosquitoes of the genus Anopheles are important vectors of Plasmodium parasites, causative agents of malaria. The aim of this review was to synthesize the overall and species-specific proportion of Anopheles species infected with sporozoites and their geographical distribution in the last 2 decades (2001-2021). METHODS A comprehensive search was conducted using databases (PubMed, Google Scholar, Science Direct, Scopus, African Journals OnLine) and manual Google search between January 1 and February 15, 2022. Original articles describing work conducted in Ethiopia, published in English and reporting infection status, were included in the review. All the required data were extracted using a standardized data extraction form, imported to SPSS-24, and analyzed accordingly. The quality of each original study was assessed using a quality assessment tool adapted from the Joanna Briggs Institute critical appraisal checklist. This study was registered on PROSPERO (International Prospective Register of Systematic Reviews; registration no. CRD42022299078). RESULTS A search for published articles produced a total of 3086 articles, of which 34 met the inclusion criteria. Data on mosquito surveillance revealed that a total of 129,410 anophelines comprising 25 species were captured, of which 48,365 comprising 21 species were tested for sporozoites. Anopheles arabiensis was the dominant species followed by An. pharoensis and An. coustani complex. The overall proportion infected with sporozoites over 21 years was 0.87%. Individual proportions included Anopheles arabiensis (1.09), An. pharoensis (0.79), An. coustani complex (0.13), An. funestus (2.71), An. demeilloni (0.31), An. stephensi (0.70), and An. cinereus (0.73). Plasmodium falciparum sporozoites accounted 79.2% of Plasmodium species. Mixed infection of Plasmodium vivax and P. falciparum was only reported from one An. arabiensis sample. CONCLUSIONS Anopheles arebiensis was the dominant malaria vector over the years, with the highest sporozoite infection proportion of 2.85% and an average of 0.90% over the years. Other species contributing to malaria transmission in the area were An. pharoensis, An. coustani complex, An. funestus, An. stephensi, and An. coustani. The emergence of new vector species, in particular An. stephensi, is particularly concerning and should be investigated further.
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Affiliation(s)
- Yibeltal Aschale
- Department of Medical Laboratory Sciences, Debre Markos University, Debre Markos, Ethiopia.
| | - Aklilu Getachew
- School of Medical Laboratory Science, Jimma University, Jimma, Ethiopia
| | | | - Antonio De Cristofaro
- Department of Agriculture, Environment and Food Sciences, University of Molise, Molise, Italy
| | - Andrea Sciarretta
- Department of Agriculture, Environment and Food Sciences, University of Molise, Molise, Italy
| | - Getnet Atenafu
- Department of Biology, Debre Markos University, Debre Markos, Ethiopia
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Waage J, Grace D, Fèvre EM, McDermott J, Lines J, Wieland B, Naylor NR, Hassell JM, Chan K. Changing food systems and infectious disease risks in low-income and middle-income countries. Lancet Planet Health 2022; 6:e760-e768. [PMID: 36087606 PMCID: PMC9451496 DOI: 10.1016/s2542-5196(22)00116-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 06/15/2023]
Abstract
The emergence of COVID-19 has drawn the attention of health researchers sharply back to the role that food systems can play in generating human disease burden. But emerging pandemic threats are just one dimension of the complex relationship between agriculture and infectious disease, which is evolving rapidly, particularly in low-income and middle-income countries (LMICs) that are undergoing rapid food system transformation. We examine this changing relationship through four current disease issues. The first is that greater investment in irrigation to improve national food security raises risks of vector-borne disease, which we illustrate with the case of malaria and rice in Africa. The second is that the intensification of livestock production in LMICs brings risks of zoonotic diseases like cysticercosis, which need to be managed as consumer demand grows. The third is that the nutritional benefits of increasing supply of fresh vegetables, fruit, and animal-sourced foods in markets in LMICs pose new food-borne disease risks, which might undermine supply. The fourth issue is that the potential human health risks of antimicrobial resistance from agriculture are intensified by changing livestock production. For each disease issue, we explore how food system transition is creating unintentional infectious disease risks, and what solutions might exist for these problems. We show that successfully addressing all of these challenges requires a coordinated approach between public health and agricultural sectors, recognising the costs and benefits of disease-reducing interventions to both, and seeking win-win solutions that are most likely to attract broad policy support and uptake by food systems.
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Affiliation(s)
- Jeff Waage
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
| | - Delia Grace
- International Livestock Research Institute, Nairobi, Kenya; Natural Resources Institute, University of Greenwich, London, UK
| | - Eric M Fèvre
- International Livestock Research Institute, Nairobi, Kenya; Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - John McDermott
- International Food Policy Research Institute, Washington, DC, USA
| | - Jo Lines
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Barbara Wieland
- International Livestock Research Institute, Nairobi, Kenya; Institute of Virology and Immunology, Mittelhäusern, Switzerland; Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Nichola R Naylor
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - James M Hassell
- International Livestock Research Institute, Nairobi, Kenya; Smithsonian National Zoo and Conservation Biology Institute, Washington, DC, USA
| | - Kallista Chan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
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Kibret S, McCartney M, Lautze J, Nhamo L, Yan G. The impact of large and small dams on malaria transmission in four basins in Africa. Sci Rep 2021; 11:13355. [PMID: 34172779 PMCID: PMC8233325 DOI: 10.1038/s41598-021-92924-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 06/17/2021] [Indexed: 11/22/2022] Open
Abstract
Expansion of various types of water infrastructure is critical to water security in Africa. To date, analysis of adverse disease impacts has focused mainly on large dams. The aim of this study was to examine the effect of both small and large dams on malaria in four river basins in sub-Saharan Africa (i.e., the Limpopo, Omo-Turkana, Volta and Zambezi river basins). The European Commission’s Joint Research Center (JRC) Yearly Water Classification History v1.0 data set was used to identify water bodies in each of the basins. Annual malaria incidence data were obtained from the Malaria Atlas Project (MAP) database for the years 2000, 2005, 2010 and 2015. A total of 4907 small dams and 258 large dams in the four basins, with 14.7million people living close (< 5 km) to their reservoirs in 2015, were analysed. The annual number of malaria cases attributable to dams of either size across the four basins was 0.9–1.7 million depending on the year, of which between 77 and 85% was due to small dams. The majority of these cases occur in areas of stable transmission. Malaria incidence per kilometre of reservoir shoreline varied between years but for small dams was typically 2–7 times greater than that for large dams in the same basin. Between 2000 and 2015, the annual malaria incidence showed a broadly declining trend for both large and small dam reservoirs in areas of stable transmission in all four basins. In conclusion, the malaria impact of dams is far greater than previously recognized. Small and large dams represent hotspots of malaria transmission and, as such, should be a critical focus of future disease control efforts.
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Affiliation(s)
- Solomon Kibret
- Program in Public Health, University of California Irvine, Irvine, CA, 92697, USA.
| | | | - Jonathan Lautze
- International Water Management Institute, Pretoria, South Africa
| | - Luxon Nhamo
- International Water Management Institute, Pretoria, South Africa.,Water Research Commission, Pretoria, South Africa
| | - Guiyun Yan
- Program in Public Health, University of California Irvine, Irvine, CA, 92697, USA
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Murindahabi MM, Takken W, Misago X, Niyituma E, Umupfasoni J, Hakizimana E, van Vliet AJH, Poortvliet PM, Mutesa L, Murindahabi NK, Koenraadt CJM. Monitoring mosquito nuisance for the development of a citizen science approach for malaria vector surveillance in Rwanda. Malar J 2021; 20:36. [PMID: 33423679 PMCID: PMC7798336 DOI: 10.1186/s12936-020-03579-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 12/31/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Many countries, including Rwanda, have mosquito monitoring programmes in place to support decision making in the fight against malaria. However, these programmes can be costly, and require technical (entomological) expertise. Involving citizens in data collection can greatly support such activities, but this has not yet been thoroughly investigated in a rural African context. METHODS Prior to the implementation of such a citizen-science approach, a household entomological survey was conducted in October-November 2017 and repeated one year later in Busoro and Ruhuha sectors, in southern and eastern province of Rwanda, respectively. The goal was to evaluate the perception of mosquito nuisance reported by citizens as a potential indicator for malaria vector hotspots. Firstly, mosquito abundance and species composition were determined using Centers for Disease Control and Prevention (CDC) light traps inside the houses. Secondly, household members were interviewed about malaria risk factors and their perceived level of mosquito nuisance. RESULTS Tiled roofs, walls made of mud and wood, as well as the number of occupants in the house were predictors for the number of mosquitoes (Culicidae) in the houses, while the presence of eaves plus walls made of mud and wood were predictors for malaria vector abundance. Perception of mosquito nuisance reported indoors tended to be significantly correlated with the number of Anopheles gambiae sensu lato (s.l.) and Culicidae collected indoors, but this varied across years and sectors. At the village level, nuisance also significantly correlated with An. gambiae s.l. and total mosquito density, but only in 2018 while not in 2017. CONCLUSIONS Perception of mosquito nuisance denoted in a questionnaire survey could be used as a global indicator of malaria vector hotspots. Hence, involving citizens in such activities can complement malaria vector surveillance and control.
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Affiliation(s)
- Marilyn Milumbu Murindahabi
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,College of Sciences and Technology, University of Rwanda, Kigali, Rwanda
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Xavier Misago
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Elias Niyituma
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Jackie Umupfasoni
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Emmanuel Hakizimana
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Arnold J H van Vliet
- Environmental Systems Analysis Group, Wageningen University & Research, Wageningen, The Netherlands
| | - P Marijn Poortvliet
- Strategic Communication Group, Wageningen University & Research, Wageningen, the Netherlands
| | - Leon Mutesa
- College of Medicine and Health Sciences, University of Rwanda, Kigali, Rwanda
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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: 11] [Impact Index Per Article: 2.8] [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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6
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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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Kibret S, Lautze J, McCartney M, Nhamo L, Yan G. Malaria around large dams in Africa: effect of environmental and transmission endemicity factors. Malar J 2019; 18:303. [PMID: 31481092 PMCID: PMC6720395 DOI: 10.1186/s12936-019-2933-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Accepted: 08/23/2019] [Indexed: 01/08/2023] Open
Abstract
Background The impact of large dams on malaria has received widespread attention. However, understanding how dam topography and transmission endemicity influence malaria incidences is limited. Methods Data from the European Commission’s Joint Research Center and Shuttle Radar Topography Mission were used to determine reservoir perimeters and shoreline slope of African dams. Georeferenced data from the Malaria Atlas Project (MAP) were used to estimate malaria incidence rates in communities near reservoir shorelines. Population data from the WorldPop database were used to estimate the population at risk of malaria around dams in stable and unstable areas. Results The data showed that people living near (< 5 km) large dams in sub-Saharan Africa grew from 14.4 million in 2000 to 18.7 million in 2015. Overall, across sub-Saharan Africa between 0.7 and 1.6 million malaria cases per year are attributable to large dams. Whilst annual malaria incidence declined markedly in both stable and unstable areas between 2000 and 2015, the malaria impact of dams appeared to increase in unstable areas, but decreased in stable areas. Shoreline slope was found to be the most important malaria risk factor in dam-affected geographies, explaining 41–82% (P < 0.001) of the variation in malaria incidence around reservoirs. Conclusion Gentler, more gradual shoreline slopes were associated with much greater malaria risk. Dam-related environmental variables such as dam topography and shoreline slopes are an important factor that should be considered in efforts to predict and control malaria around dams.
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Affiliation(s)
- Solomon Kibret
- Program in Public Health, University of California Irvine, Irvine, CA, 92697, USA
| | - Jonathan Lautze
- International Water Management Institute, Pretoria, South Africa
| | | | - Luxon Nhamo
- International Water Management Institute, Pretoria, South Africa
| | - Guiyun Yan
- Program in Public Health, University of California Irvine, Irvine, CA, 92697, USA.
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Kibret S, Glenn Wilson G, Ryder D, Tekie H, Petros B. Environmental and meteorological factors linked to malaria transmission around large dams at three ecological settings in Ethiopia. Malar J 2019; 18:54. [PMID: 30808343 PMCID: PMC6390543 DOI: 10.1186/s12936-019-2689-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/21/2019] [Indexed: 01/09/2023] Open
Abstract
Background A growing body of evidence suggests that dams intensify malaria transmission in sub-Saharan Africa. However, the environmental characteristics underpinning patterns in malaria transmission around dams are poorly understood. This study investigated local-scale environmental and meteorological variables linked to malaria transmission around three large dams in Ethiopia. Methods Monthly malaria incidence data (2010–2014) were collected from health centres around three dams located at lowland, midland and highland elevations in Ethiopia. Environmental (elevation, distance from the reservoir shoreline, Normalized Difference Vegetation Index (NDVI), monthly reservoir water level, monthly changes in water level) and meteorological (precipitation, and minimum and maximum air temperature) data were analysed to determine their relationship with monthly malaria transmission at each dam using correlation and stepwise multiple regression analysis. Results Village distance to reservoir shoreline (lagged by 1 and 2 months) and monthly change in water level (lagged by 1 month) were significantly correlated with malaria incidence at all three dams, while NDVI (lagged by 1 and 2 months) and monthly reservoir water level (lagged by 2 months) were found to have a significant influence at only the lowland and midland dams. Precipitation (lagged by 1 and 2 months) was also significantly associated with malaria incidence, but only at the lowland dam, while minimum and maximum air temperatures (lagged by 1 and 2 months) were important factors at only the highland dam. Conclusion This study confirmed that reservoir-associated factors (distance from reservoir shoreline, monthly average reservoir water level, monthly water level change) were important predictors of increased malaria incidence in villages around Ethiopian dams in all elevation settings. Reservoir water level management should be considered as an additional malaria vector control tool to help manage malaria transmission around dams. Electronic supplementary material The online version of this article (10.1186/s12936-019-2689-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Solomon Kibret
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia. .,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.,Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Darren Ryder
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
| | - Habte Tekie
- Department of Zoological Sciences, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Beyene Petros
- Department of Microbial, Cellular and Molecular Biology, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia
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Hakizimana E, Karema C, Munyakanage D, Githure J, Mazarati JB, Tongren JE, Takken W, Binagwaho A, Koenraadt CJ. Spatio-temporal distribution of mosquitoes and risk of malaria infection in Rwanda. Acta Trop 2018; 182:149-157. [PMID: 29476726 DOI: 10.1016/j.actatropica.2018.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/26/2018] [Accepted: 02/11/2018] [Indexed: 11/24/2022]
Abstract
To date, the Republic of Rwanda has not systematically reported on distribution, diversity and malaria infectivity rate of mosquito species throughout the country. Therefore, we assessed the spatial and temporal variation of mosquitoes in the domestic environment, as well as the nocturnal biting behavior and infection patterns of the main malaria vectors in Rwanda. For this purpose, mosquitoes were collected monthly from 2010 to 2013 by human landing catches (HLC) and pyrethrum spray collections (PSC) in seven sentinel sites. Mosquitoes were identified using morphological characteristics and PCR. Plasmodium falciparum sporozoite infection rates were determined using ELISA. A total of 340,684 mosquitoes was collected by HLC and 73.8% were morphologically identified as culicines and 26.2% as anophelines. Of the latter, 94.3% were Anopheles gambiae s.l., 0.4% Anopheles funestus and 5.3% other Anopheles species. Of An. gambiae s.l., An. arabiensis and An. gambiae s.s. represented 84.4% and 15.6%, respectively. Of all An. gambiae s.l. collected indoor and outdoor, the proportion collected indoors was 51.3% in 2010 and 44.9% in 2013. A total of 17,022 mosquitoes was collected by PSC of which 20.5% were An. gambiae s.l. and 79.5% were culicines. For the seven sentinel sites, the mean indoor density for An. gambiae s.l. varied from 0.0 to 1.0 mosquitoes/house/night. P. falciparum infection rates in mosquitoes varied from 0.87 to 4.06%. The entomological inoculation rate (EIR) ranged from 1.0 to 329.8 with an annual average of 99.5 infective bites/person/year. This longitudinal study shows, for the first time, the abundance, species composition, and entomological inoculation rate of malaria mosquitoes collected throughout Rwanda.
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10
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Kibret S, Wilson GG, Ryder D, Tekie H, Petros B. Can water-level management reduce malaria mosquito abundance around large dams in sub-Saharan Africa? PLoS One 2018; 13:e0196064. [PMID: 29672560 PMCID: PMC5909510 DOI: 10.1371/journal.pone.0196064] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 04/05/2018] [Indexed: 11/23/2022] Open
Abstract
Background Water level management has been suggested as a potential tool to reduce malaria around large reservoirs. However, no field-based test has been conducted to assess the effect of water level management on mosquito larval abundance in African settings. The objective of the present study is to evaluate the effects of water level drawdown rates on mosquito larval abundance. Methods Twelve experimental dams were constructed on the foreshore of the Koka Dam in Ethiopia. These were grouped into four daily water drawdown treatments, each with three replicates: no water-level drawdown (Group 1; Control), 10 mm.d-1 (Group 2), 15 mm.d-1 (Group 3) and 20 mm.d-1 (Group 4). Larval sampling was conducted weekly for a period of 6 weeks each in the main malaria transmission season (October to November 2013) and subsequent dry season (February to March 2014). Larval densities were compared among treatments over time using repeated measures Analysis of Variance (ANOVA). Results A total of 284 Anopheles mosquito larvae were collected from the experimental dams during the study period. Most (63.4%; n = 180) were collected during the main malaria transmission season while the remaining (36.6%; n = 104) were collected during the dry season. Larvae comprised four Anopheles species, dominated by Anopheles arabiensis (48.1% of total larval samples; n = 136) and An. pharoensis (33.2%; n = 94). Mean larval density was highest in control treatment dams with stable water levels throughout the study, and decreased significantly (P < 0.05) with increasing water drawdown rates in both seasons. During the main transmission season, anopheline larval density was generally lower by 30%, 70% and 84% in Groups 2, Group 3 and Group 4, respectively, compared with the control dams (Group 1). In the dry season, larval density was reduced by 45%, 70% and 84% in Groups 2, Group 3 and Group 4, respectively, when compared to the control dams. Conclusion Increased water drawdown rates were associated with lower mosquito larval abundance. Water level management could thus serve as a potential control measure for malaria vectors around reservoirs by regulating the persistence of shallow shoreline breeding habitats. Dam operators and water resource managers should consider incorporating water level management as a malaria control mechanism into routine dam operations to manage the risk of malaria transmission to human populations around reservoirs.
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Affiliation(s)
- Solomon Kibret
- Ecosystem Management, University of New England, NSW, Armidale, Australia
- * E-mail:
| | - G. Glenn Wilson
- Ecosystem Management, University of New England, NSW, Armidale, Australia
| | - Darren Ryder
- Ecosystem Management, University of New England, NSW, Armidale, Australia
| | - Habte Tekie
- Department of Zoological Sciences, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Beyene Petros
- Department of Microbial, Cellular and Molecular Biology, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia
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Ouedraogo B, Inoue Y, Kambiré A, Sallah K, Dieng S, Tine R, Rouamba T, Herbreteau V, Sawadogo Y, Ouedraogo LSLW, Yaka P, Ouedraogo EK, Dufour JC, Gaudart J. Spatio-temporal dynamic of malaria in Ouagadougou, Burkina Faso, 2011-2015. Malar J 2018; 17:138. [PMID: 29609606 PMCID: PMC5879937 DOI: 10.1186/s12936-018-2280-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 03/21/2018] [Indexed: 11/25/2022] Open
Abstract
Background Given the scarcity of resources in developing countries, malaria treatment requires new strategies that target specific populations, time periods and geographical areas. While the spatial pattern of malaria transmission is known to vary depending on local conditions, its temporal evolution has yet to be evaluated. The aim of this study was to determine the spatio-temporal dynamic of malaria in the central region of Burkina Faso, taking into account meteorological factors. Methods Drawing on national databases, 101 health areas were studied from 2011 to 2015, together with weekly meteorological data (temperature, number of rain events, rainfall, humidity, wind speed). Meteorological factors were investigated using a principal component analysis (PCA) to reduce dimensions and avoid collinearities. The Box–Jenkins ARIMA model was used to test the stationarity of the time series. The impact of meteorological factors on malaria incidence was measured with a general additive model. A change-point analysis was performed to detect malaria transmission periods. For each transmission period, malaria incidence was mapped and hotspots were identified using spatial cluster detection. Results Malaria incidence never went below 13.7 cases/10,000 person-weeks. The first and second PCA components (constituted by rain/humidity and temperatures, respectively) were correlated with malaria incidence with a lag of 2 weeks. The impact of temperature was significantly non-linear: malaria incidence increased with temperature but declined sharply with high temperature. A significant positive linear trend was found for the entire time period. Three transmission periods were detected: low (16.8–29.9 cases/10,000 person-weeks), high (51.7–84.8 cases/10,000 person-weeks), and intermediate (26.7–32.2 cases/10,000 person-weeks). The location of clusters identified as high risk varied little across transmission periods. Conclusion This study highlighted the spatial variability and relative temporal stability of malaria incidence around the capital Ouagadougou, in the central region of Burkina Faso. Despite increasing efforts in fighting the disease, malaria incidence remained high and increased over the period of study. Hotspots, particularly those detected for low transmission periods, should be investigated further to uncover the local environmental and behavioural factors of transmission, and hence to allow for the development of better targeted control strategies. Electronic supplementary material The online version of this article (10.1186/s12936-018-2280-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Boukary Ouedraogo
- Aix Marseille Univ, INSERM, IRD, SESSTIM UMR1252 Sciences Economiques & Sociales de la Santé & Traitement de l'Information Médicale, Marseille, France.
| | - Yasuko Inoue
- Aix Marseille Univ, INSERM, IRD, SESSTIM UMR1252 Sciences Economiques & Sociales de la Santé & Traitement de l'Information Médicale, Marseille, France.,Embassy of Japan in the Republic of Guinea, Conakry, Guinea
| | - Alinsa Kambiré
- Aix Marseille Univ, INSERM, IRD, SESSTIM UMR1252 Sciences Economiques & Sociales de la Santé & Traitement de l'Information Médicale, Marseille, France
| | - Kankoe Sallah
- Aix Marseille Univ, INSERM, IRD, SESSTIM UMR1252 Sciences Economiques & Sociales de la Santé & Traitement de l'Information Médicale, Marseille, France.,Prospective et Coopération, Laboratoire d'Idées, Bureau d'Etudes Recherche, Marseille, France
| | - Sokhna Dieng
- Aix Marseille Univ, INSERM, IRD, SESSTIM UMR1252 Sciences Economiques & Sociales de la Santé & Traitement de l'Information Médicale, Marseille, France.,Ecole des Hautes Etudes en Santé Publique, Rennes, France
| | - Raphael Tine
- Aix Marseille Univ, INSERM, IRD, SESSTIM UMR1252 Sciences Economiques & Sociales de la Santé & Traitement de l'Information Médicale, Marseille, France
| | - Toussaint Rouamba
- Aix Marseille Univ, INSERM, IRD, SESSTIM UMR1252 Sciences Economiques & Sociales de la Santé & Traitement de l'Information Médicale, Marseille, France.,Université libre de Bruxelles, EPS, Centre de Recherche en Epidémiologie, Biostatistique et Recherche Clinique, Brussels, Belgium.,IRSS-Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | | | - Yacouba Sawadogo
- Programme National de Lutte contre le Paludisme, Ministère de la Santé, Ouagadougou, Burkina Faso
| | | | - Pascal Yaka
- Direction de la Météorologie, Ministère des Transports, Ouagadougou, Burkina Faso
| | - Ernest K Ouedraogo
- Direction de la Météorologie, Ministère des Transports, Ouagadougou, Burkina Faso
| | - Jean-Charles Dufour
- Aix Marseille Univ, INSERM, IRD, SESSTIM UMR1252 Sciences Economiques & Sociales de la Santé & Traitement de l'Information Médicale, Marseille, France
| | - Jean Gaudart
- Aix Marseille Univ, INSERM, IRD, SESSTIM UMR1252 Sciences Economiques & Sociales de la Santé & Traitement de l'Information Médicale, Marseille, France
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Kibret S, Wilson GG, Ryder D, Tekie H, Petros B. The Influence of Dams on Malaria Transmission in Sub-Saharan Africa. ECOHEALTH 2017; 14:408-419. [PMID: 25894956 DOI: 10.1007/s10393-015-1029-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 03/22/2015] [Accepted: 03/25/2015] [Indexed: 06/04/2023]
Abstract
The construction of dams in sub-Saharan Africa is pivotal for food security and alleviating poverty in the region. However, the unintended adverse public health implications of extending the spatial distribution of water infrastructure are poorly documented and may minimize the intended benefits of securing water supplies. This paper reviews existing studies on the influence of dams on the spatial distribution of malaria parasites and vectors in sub-Saharan Africa. Common themes emerging from the literature were that dams intensified malaria transmission in semi-arid and highland areas with unstable malaria transmission but had little or no impact in areas with perennial transmission. Differences in the impacts of dams resulted from the types and characteristics of malaria vectors and their breeding habitats in different settings of sub-Saharan Africa. A higher abundance of a less anthropophilic Anopheles arabiensis than a highly efficient vector A. gambiae explains why dams did not increase malaria in stable areas. In unstable areas where transmission is limited by availability of water bodies for vector breeding, dams generally increase malaria by providing breeding habitats for prominent malaria vector species. Integrated vector control measures that include reservoir management, coupled with conventional malaria control strategies, could optimize a reduction of the risk of malaria transmission around dams in the region.
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Affiliation(s)
- Solomon Kibret
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW2351, Australia.
| | - G Glenn Wilson
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW2351, Australia
| | - Darren Ryder
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW2351, 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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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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Kibret S, Lautze J, McCartney M, Nhamo L, Wilson GG. Malaria and large dams in sub-Saharan Africa: future impacts in a changing climate. Malar J 2016; 15:448. [PMID: 27592590 PMCID: PMC5011356 DOI: 10.1186/s12936-016-1498-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 08/18/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sub-Saharan Africa (SSA) has embarked on a new era of dam building to improve food security and promote economic development. Nonetheless, the future impacts of dams on malaria transmission are poorly understood and seldom investigated in the context of climate and demographic change. METHODS The distribution of malaria in the vicinity of 1268 existing dams in SSA was mapped under the Intergovernmental Panel on Climate Change (IPCC) representative concentration pathways (RCP) 2.6 and 8.5. Population projections and malaria incidence estimates were used to compute population at risk of malaria in both RCPs. Assuming no change in socio-economic interventions that may mitigate impacts, the change in malaria stability and malaria burden in the vicinity of the dams was calculated for the two RCPs through to the 2080s. Results were compared against the 2010 baseline. The annual number of malaria cases associated with dams and climate change was determined for each of the RCPs. RESULTS The number of dams located in malarious areas is projected to increase in both RCPs. Population growth will add to the risk of transmission. The population at risk of malaria around existing dams and associated reservoirs, is estimated to increase from 15 million in 2010 to 21-23 million in the 2020s, 25-26 million in the 2050s and 28-29 million in the 2080s, depending on RCP. The number of malaria cases associated with dams in malarious areas is expected to increase from 1.1 million in 2010 to 1.2-1.6 million in the 2020s, 2.1-3.0 million in the 2050s and 2.4-3.0 million in the 2080s depending on RCP. The number of cases will always be higher in RCP 8.5 than RCP 2.6. CONCLUSION In the absence of changes in other factors that affect transmission (e.g., socio-economic), the impact of dams on malaria in SSA will be significantly exacerbated by climate change and increases in population. Areas without malaria transmission at present, which will transition to regions of unstable transmission, may be worst affected. Modifying conventional water management frameworks to improve malaria control, holds the potential to mitigate some of this increase and should be more actively implemented.
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Affiliation(s)
- Solomon Kibret
- Program in Public Health, University of California Irvine, Irvine, CA, 92697, USA.
| | - Jonathan Lautze
- International Water Management Institute, Pretoria, South Africa
| | - Matthew McCartney
- International Water Management Institute, Vientiane, Lao People's Democratic Republic
| | - Luxon Nhamo
- International Water Management Institute, Pretoria, South Africa
| | - G Glenn Wilson
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
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Zhou G, Yewhalaw D, Lo E, Zhong D, Wang X, Degefa T, Zemene E, Lee MC, Kebede E, Tushune K, Yan G. Analysis of asymptomatic and clinical malaria in urban and suburban settings of southwestern Ethiopia in the context of sustaining malaria control and approaching elimination. Malar J 2016; 15:250. [PMID: 27129785 PMCID: PMC4851815 DOI: 10.1186/s12936-016-1298-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 04/15/2016] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Malaria intervention in Ethiopia has been strengthened significantly in the past decade. The Ethiopian government recently stratified the country based upon annual parasite incidence into malaria free, low, moderate and high transmission strata. Districts with low transmission were targeted for indigenous transmission elimination. Surveillance on malaria disease incidence is needed for planning control and elimination efforts. METHODS Clinical malaria was monitored prospectively in health facilities in Jimma town, Oromia Region, southwestern Ethiopia from July 2014 to June 2015. Seasonal cross-sectional parasite prevalence surveys in local communities were conducted in 2014 and 2015 in eight kebeles. Case report forms were administered to obtain sociodemographic and epidemiological information from patients. RESULTS A total of 1434 suspected malaria cases were examined from the health facilities and 428 confirmed malaria cases were found. Among them, 327 (76.4 %) cases were Plasmodium vivax, 97 (22.7 %) were Plasmodium falciparum, and 4 (0.9 %) were mixed infection of P. vivax and P. falciparum. The annual malaria incidence rate was 1.7 cases per 1000 people at risk. Parasite prevalence in the community was less than 3 %. Household ownership of insecticide-treated nets (ITNs) was 47.3 % (1173/2479) and ITN usage was 37.9 %. All ITNs were long-lasting insecticidal nets, and repellent use was not found in the study area. Being male and traveling were the significant risk factors for P. falciparum malaria. For P. vivax malaria, risk factors included occupation and history of malaria illness during the preceding 30 days. CONCLUSION Epidemiological evidence suggested low clinical malaria incidence and prevalence in Jimma town. More aggressive measures may be needed to further suppress vivax transmission. Strategies should be planned targeting sustained control and elimination.
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Affiliation(s)
- Guofa Zhou
- />Program in Public Health, University of California, Irvine, CA 92617 USA
| | - Delenasaw Yewhalaw
- />Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
- />Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Eugenia Lo
- />Program in Public Health, University of California, Irvine, CA 92617 USA
| | - Daibin Zhong
- />Program in Public Health, University of California, Irvine, CA 92617 USA
| | - Xiaoming Wang
- />Program in Public Health, University of California, Irvine, CA 92617 USA
| | - Teshome Degefa
- />Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Endalew Zemene
- />Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Ming-chieh Lee
- />Program in Public Health, University of California, Irvine, CA 92617 USA
| | - Estifanos Kebede
- />Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Kora Tushune
- />Department of Health Management, College of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Guiyun Yan
- />Program in Public Health, University of California, Irvine, CA 92617 USA
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Kibret S, Lautze J, McCartney M, Wilson GG, Nhamo L. Malaria impact of large dams in sub-Saharan Africa: maps, estimates and predictions. Malar J 2015; 14:339. [PMID: 26337834 PMCID: PMC4560078 DOI: 10.1186/s12936-015-0873-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 08/26/2015] [Indexed: 11/24/2022] Open
Abstract
Background While there is growing recognition of the malaria impacts of large dams in sub-Saharan Africa, the cumulative malaria impact of reservoirs associated with current and future dam developments has not been quantified. The objective of this study was to estimate the current and predict the future impact of large dams on malaria in different eco-epidemiological settings across sub-Saharan Africa. Methods The locations of 1268 existing and 78 planned large dams in sub-Saharan Africa were mapped against the malaria stability index (stable, unstable and no malaria). The Plasmodium falciparum infection rate (PfIR) was determined for populations at different distances (<1, 1–2, 2–5, 5–9 km) from the associated reservoirs using the Malaria Atlas Project (MAP) and WorldPop databases. Results derived from MAP were verified by comparison with the results of detailed epidemiological studies conducted at 11 dams. Results Of the 1268 existing dams, 723 are located in malarious areas. Currently, about 15 million people live in close proximity (<5 km) to the reservoirs associated with these dams. A total of 1.1 million malaria cases annually are associated with them: 919,000 cases due to the presence of 416 dams in areas of unstable transmission and 204,000 cases due to the presence of 307 dams in areas of stable transmission. Of the 78 planned dams, 60 will be located in malarious areas and these will create an additional 56,000 cases annually. The variation in annual PfIR in communities as a function of distance from reservoirs was statistically significant in areas of unstable transmission but not in areas of stable transmission. Conclusion In sub-Saharan Africa, dams contribute significantly to malaria risk particularly in areas of unstable transmission. Additional malaria control measures are thus required to reduce the impact of dams on malaria.
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Affiliation(s)
- Solomon Kibret
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia.
| | - Jonathan Lautze
- International Water Management Institute, Pretoria, South Africa.
| | | | - G Glenn Wilson
- Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia.
| | - Luxon Nhamo
- International Water Management Institute, Pretoria, South Africa.
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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: 57] [Impact Index Per Article: 5.7] [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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