Impacts of Climate Change on Malaria

There has been growing concern in both climatological and medical communities that global climate change is likely to have wide ranging impacts on health. The potential health effects from these consequences are many. Overall, negative health impacts may outweigh the positive ones. The major potential health impacts have been classified as direct and indirect impacts), according to whether they occur predominantly via the direct effect of exacerbated values of one or more climate variables (e.g., temperature, precipitation, solar radiation) on the human organism or are mediated by climate-induced changes in complex biogeochemical processes or climatic influences on other environmental health hazards. The determinants of malaria vector growth and transmission at the local level include temperature, precipitation, humidity, population distribution, level of poverty, land use, irrigation, and other socioeconomic parameters. Where as at the global level, the driving forces are the Northern Hemispheric temperature, Sea surface temperatures and El-Nino Southern Oscillation events. The Transmission windows of opportunity conducive to malarial vector growth and transmission are unique to India and are defined in terms of climate parameters as Class I, Class II and Class III which correspond to different temperature ranges and durations when the humidity persists between 60% to 80%. This differs from state to state as the topography and land use changes have variability. As an example, it is observed that in Gujarat, maximum incidences are observed in the months of June, July and August when humidity ranges between 60% and 80% at temperatures 25oC to 30oC, which persist for minimum 6 to 10 days in a month.

Preliminary analysis indicates that that in 2080, malaria will find more windows of opportunity at higher latitudes and altitudes. In the climate change scenario, preliminary investigations indicate that 10% more states will have transmission windows open for all the 12 months w.r.t the 2000 malaria scenario. The transmission windows in northern states of Jammu and Kashmir and the western state of Rajasthan are likely to increase by 3 to 5 months. In the southern states, however, the window is likely to shorten by 2 to 3 months w.r.t the existing windows, which already have high threshold temperatures and with climate change the threshold levels, will go up further. The results presented here are not predictions of the future. Rather, they point towards the possible changes in malaria transmission windows in the country, given the assumptions made.

Transmission windows of malaria in different states of India (a) in 2000 (b) in 2080

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GEF Project Implemented by UNDP

Implementing & Executing Agency Ministry of Environment and Forests Government of India

Facilitating Agency Winrock International India

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