[NEW DELHI] Climate change is likely to spread malaria to new areas in the Indian Himalayas, and lengthen the periods in which the infection is spread in a number of districts, according to projections from malaria researchers in India.
But the country's east coast could see fewer malaria cases by 2030, because of rising temperatures which affect mosquitoes' activity, they said.
The projections by the National Institute of Malaria Research (NIMR), Delhi, published in a special issue of Current Science on climate change yesterday (10 August), indicate that malaria could spread to districts in three states it is currently absent from — Uttarakhand, Arunachal Pradesh, and Jammu and Kashmir — during the next 20 years.
In the eastern Himalayas, in north-eastern India, the window of malaria transmission would increase from 7–9 to 10–12 months in length. The region is humid and wet, with mild winters, which makes it "highly conducive for mosquito breeding, survival and transmission" of vector-borne diseases.
But India's east coast would have reduced transmission, because of an increase in temperature, and the western regions would see a minimal impact, the analysis showed.
The study is one of several by the Indian Network of Climate Change Assessment programme at the Ministry of Environment and Forests. It used the regional climate modelling system developed by the Hadley Centre, United Kingdom, to analyse temperature and relative humidity scenarios across India, and mapped districts to show 'transmission windows' during which infection is spread.
The researchers said higher temperatures increased the rate at which malaria-carrying mosquitoes digested their blood meal and laid eggs.
But, the report cautions, this climate assessment needs to be integrated with socio-economic factors, as transmission is also driven by crop practices, water availability, urbanisation, and interventions such as bednets and insecticide sprays.
Aditya Prasad Dash, regional advisor for vector-borne and neglected tropical diseases at the WHO's regional office for South-East Asia (SEARO), told SciDev.Net that SEARO has developed research protocols to analyse the impact of climate change impact on diarrhoeal and vector-borne diseases. It is now analysing the history and future of malaria, and preparedness for it in the region.
Strengthening health infrastructure and educating communities in vulnerable areas are the key tools, he said.
"In already endemic areas, for example in north-eastern states of India, then best available tools, such as long-lasting nets for personal protection and combination therapy to combat drug-resistant malaria, are showing dividends," Dash said.
He added that Indian scientists need to identify bottlenecks in malaria control measures and assess the capacity of society to adapt to the new threats posed by climate change.
Current Science 101 (3), 372-383 (2011)