Health / Santé

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    Predicting and mapping malaria under climate change scenarios : the potential redistribution of malaria vectors in Africa
    (BioMed Central, 2010) Kangalawe, Richard Y.M.; Yanda, Pius Z.
    Background: Malaria is rampant in Africa and causes untold mortality and morbidity. Vector-borne diseases are climate sensitive and this has raised considerable concern over the implications of climate change on future disease risk. The problem of malaria vectors (Anopheles mosquitoes) shifting from their traditional locations to invade new zones is an important concern. The vision of this study was to exploit the sets of information previously generated by entomologists, e.g. on geographical range of vectors and malaria distribution, to build models that will enable prediction and mapping the potential redistribution of Anopheles mosquitoes in Africa. Methods: The development of the modelling tool was carried out through calibration of CLIMEX parameters. The model helped estimate the potential geographical distribution and seasonal abundance of the species in relation to climatic factors. These included temperature, rainfall and relative humidity, which characterized the living environment for Anopheles mosquitoes. The same parameters were used in determining the ecoclimatic index (EI). The EI values were exported to a GIS package for special analysis and proper mapping of the potential future distribution of Anopheles gambiae and Anophles arabiensis within the African continent under three climate change scenarios. Results: These results have shown that shifts in these species boundaries southward and eastward of Africa may occur rather than jumps into quite different climatic environments. In the absence of adequate control, these predictions are crucial in understanding the possible future geographical range of the vectors and the disease, which could facilitate planning for various adaptation options. Conclusion: Thus, the outputs from this study will be helpful at various levels of decision making, for example, in setting up of an early warning and sustainable strategies for climate change and climate change adaptation for malaria vectors control programmes in Africa.
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    Identification of malaria transmission and epidemic hotspots in the western Kenya highlands : its application to malaria epidemic prediction
    (BioMed Central, London, GB, 2011) Wanjala, Christine L.; Waitumbi, John; Zhou, Guofa; Githeko, Andrew K.
    Conducted in five sites in the western Kenya highlands, two U-shaped valleys (Iguhu, Emutete), two V-shaped valleys (Marani, Fort-Ternan) and one plateau (Shikondi) for 16 months, this detailed study examines how highlands terrain affects exposure and sensitivity to malaria. It shows that V-shaped ecosystems, and the plateau ecosystem have very low malaria prevalence and few individuals with an immune response to two major malaria antigens. The U-shaped ecosystems are transmission hotspots. However, because V-shaped ecosystems have very low malaria prevalence and few individuals with an immune response, they can be considered as probable epidemic hotspots.
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    Surveillance of vector populations and malaria transmission during the 2009/10 El Niño event in the Western Kenya highlands : opportunities for early detection of malaria hyper-transmission
    (BioMed Central, London, GB, 2011) Ototo, Ednah N.; Githeko, Andrew K.; Wanjala, Christine L.; Scott, Thomas W.
    Climate variability resulting from events such as El Niño increases the likelihood of malaria transmission in western Kenya. This study measures vectors collected in western Kenya highlands in four selected villages, categorized into two valley systems, the U-shaped (Iguhu and Emutete) and the V-shaped valleys (Marani and Fort Ternan) over an eight month period. Results show how the changing malaria transmission rates in the highlands will lead to more unstable transmission, decreased immunity and a high vulnerability to epidemics, unless surveillance tools are improved and effective vector control is sustained.