Zoom in at African country level: potential climate induced changes in areas of suitability for survival of malaria vectors

Abstract

BackgroundPredicting anopheles vectors’ population densities and boundary shifts is crucial in preparing for malaria risks and unanticipated outbreaks. Although shifts in the distribution and boundaries of the major malaria vectors (Anopheles gambiae s.s. and An. arabiensis) across Africa have been predicted, quantified areas of absolute change in zone of suitability for their survival have not been defined. In this study, we have quantified areas of absolute change conducive for the establishment and survival of these vectors, per African country, under two climate change scenarios and based on our findings, highlight practical measures for effective malaria control in the face of changing climatic patterns.MethodsWe developed a model using CLIMEX simulation platform to estimate the potential geographical distribution and seasonal abundance of these malaria vectors in relation to climatic factors (temperature, rainfall and relative humidity). The model yielded an eco-climatic index (EI) describing the total favourable geographical locations for the species. The EI values were classified and exported to a GIS package. Using ArcGIS, the EI shape points were clipped to the extent of Africa and then converted to a raster layer using Inverse Distance Weighted (IDW) interpolation method. Generated maps were then transformed into polygon-based geo-referenced data set and their areas computed and expressed in square kilometers (km2).ResultsFive classes of EI were derived indicating the level of survivorship of these malaria vectors. The proportion of areas increasing or decreasing in level of survival of these malaria vectors will be more pronounced in eastern and southern African countries than those in western Africa. Angola, Ethiopia, Kenya, Mozambique, Tanzania, South Africa and Zambia appear most likely to be affected in terms of absolute change of malaria vectors suitability zones under the selected climate change scenarios.ConclusionThe potential shifts of these malaria vectors have implications for human exposure to malaria, as recrudescence of the disease is likely to be recorded in several new areas and regions. Therefore, the need to develop, compile and share malaria preventive measures, which can be adapted to different climatic scenarios, remains crucial.

Evaluation of the impacts of climate change on disease vectors through ecological niche modelling

“…The distributions of two malaria vectors in Sub-Saharan Africa, Anopheles gambiae and An. arabiensis, will also likely expand southwards and southeastwards, according to ENMs involving climate change scenarios (Peterson, 2009;Fuller et al, 2012;Tonnang et al, 2010Tonnang et al, , 2014. By adding mosquito survival rates to niche models, it was concluded that East African countries will have greater climatic suitability for these vectors in the coming decades than West African countries (Tonnang et al, 2014).…”

“…arabiensis, will also likely expand southwards and southeastwards, according to ENMs involving climate change scenarios (Peterson, 2009;Fuller et al, 2012;Tonnang et al, 2010Tonnang et al, , 2014. By adding mosquito survival rates to niche models, it was concluded that East African countries will have greater climatic suitability for these vectors in the coming decades than West African countries (Tonnang et al, 2014). Although the models predict local regions of both increase and decrease of climatic suitability for the vectors, 11-30% fewer people should be exposed to the vectors in the coming decades, as seen by overlaying model predictions and human distribution (Peterson, 2009).…”

The Association of Weather Variability and Under Five Malaria Mortality in KEMRI/CDC HDSS in Western Kenya 2003 to 2008: A Time Series Analysis

“…Several studies [ 6 , 7 , 8 , 9 ] have been conducted to illuminate the effect of weather factors, mainly temperature and rainfall, on malaria vector proliferation. The mosquito vectors of malaria parasites are sensitive to changes in climate.…”

Modelling Allee effects in a transgenic mosquito population during range expansion

“…albopictus and Aedes aegypti increased in the United States [10]. Although Anopheles gambiae have not spread outside of Africa, their geographical range has shifted [31]. While mosquitoes are endemic to many locations, other places observe seasonal variation in their populations.…”