Much of the subsequent increase in malaria transmission could be realised by 2041-2070, according to the study
Climate change projections have yielded predictions about African regions more vulnerable to future malaria outbreaks: The growing climate crisis could affect the distribution and intensity of disease transmission in Africa over the next century, according to a recent study.
Malaria is a climate-sensitive vector-borne disease responsible for an estimated 435,000 deaths from 219 million malaria cases worldwide in 2017. At least 92 per cent of these deaths were reported in Africa.
A detailed mapping of malaria transmission is vital for the distribution of health resources and targeting of control measures.
According to the study, published in Nature Communications on August 28, 2020, ambient air temperature controls the rate of several components of malaria transmission.
Earlier, monthly rainfall was typically used as a proxy for habitat availability. However, more complex hydrological processes such as infiltration, soil moisture, evaporation etc, need to be factored in to assess the intensity of malaria transmission in Africa more accurately.
The study, led by Universities of Leeds and Lincoln in the United Kingdom, combined a malaria climatic suitability model with a continental-scale hydrological model that represented real-world processes of evaporation, infiltration and flow through rivers.
The study found that while flowing water in large river channels did not provide suitable larval habitat for African vector mosquitoes, associated smaller water bodies in adjacent bankside and floodplain areas could make for ideal larval breeding ground.
The river corridors could be the most prominent hot spots of malaria transmission, according to the study.
The study identified the Niger and Senegal rivers in Mali and Senegal, and the Webi Juba and Webi Shabeelie rivers in Somalia, as suitable for malaria transmission despite extending beyond the geographical ranges predicted to be climatically suitable for malaria by all rainfall thresholds.
Overall, the findings showed very minor future changes in the total area suitable for malaria transmission; the geographical location of many of those areas, however, was found to shift substantially.
In the majority of models studied, an increase in malaria transmission is preceded by a decrease from 1971-2005 to 2011-2040. Much of the subsequent increase is realised by 2041-2070.
Mark Smith, the study’s lead author, said:
“Since the huge efforts to eradicate malaria from parts of the world, the areas where we observe malaria today are only a part of the total area that would otherwise be suitable for malaria transmission. But if we are to project the impact of climate change on the geography of malaria transmission, we need to develop more sophisticated ways of representing that envelope of malaria suitability both today and in the future.”
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