Abstract
BackgroundThe 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.MethodsMalaria 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).ResultsAn. 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.ConclusionsThese 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0711-0) contains supplementary material, which is available to authorized users.
Highlights
The influence of environmental and climatic factors on malaria vector bionomics and transmission is an important topic in the context of climatic change at macro-geographical level
We examined the influence of different landscape classes on malaria vector abundance and infection rates in a Sahelian area of Senegal characterised naturally by a low level of malaria transmission, high interannual variability of climate changes [17] and high morbidity rates during seasons with heavy rainfall [18]
Mosquito collection A total of 7652 Anopheles specimens belonging to 6 species were collected by pyrethrum spray catches (PSC) from the four landscape classes (Table 2)
Summary
The influence of environmental and climatic factors on malaria vector bionomics and transmission is an important topic in the context of climatic change at macro-geographical level. Many studies suggest that climate change would lead to a resurgence of vector-borne diseases like malaria [2,3] and it is well known that malaria transmission and prevalence could be highly influenced by spatial and temporal changes in the environment [4]. This is important in non-endemic areas characterised by a low level of malaria transmission and a high variability of climatic and environmental parameters, where a comeback or resurgence of malaria with a high risk of morbidity and mortality in all age groups is expected. Water and pastural availability determine human settlements with a direct impact on land cover and use
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