Global warming is increasing the incidence of malaria at higher elevations in the tropics, particularly the highlands of Africa and South America, a new study says.
Should temperatures continue to rise, the researchers report, malaria could spread into highly populated upland regions that historically have provided havens from the mosquito-borne disease.
Cooler temperatures inhibit the population growth and biting rate of the transmitting mosquitoes as well as the development of the malaria parasites inside them.
Accounting for factors that could skew the study’s results, such as variations in rainfall and the use of insecticides and anti-malarial drugs, the researchers found that more cases of malaria were reported at higher elevations during warmer years.
At the peak of the malaria season in Ethiopia, the increase ranged from 35 to 64 per cent per 1 degree Celsius, compared with about 10 to 80 per cent in Colombia.
The study, published in the journal Science, predicts that without malaria control efforts there could be hundreds of thousands more infections a year in Africa and South America alone from just a one-degree rise in temperature.
Symptoms of malaria, which can quickly become life-threatening if not treated, include fever, headache and vomiting.
The World Health Organisation estimates there were 207 million cases of malaria in 2012, resulting in some 6,27,000 deaths. Ninety per cent of all malaria deaths occur in sub-Saharan Africa.