Global warming may cause rise in malaria

A new study by University of Michigan suggests that global warming cannot be ruled out as a contributor to the rise in malaria as mosquitoes thrive in warm conditions.

Other factors such as drug and pesticide resistance, changing land and human migration may also play roles, but climate change cannot be disregarded, says theoretical ecologist Mercedes Pascual.
 
“Our results do not mean that temperature is the only or the main factor driving the increase in malaria, but that it is one of many factors that should be considered,” she said.
 
Malaria is nearly or completely eradicated in many parts of the world but the disease still affects hundreds of millions of people globally and is intensifying in some highland regions and desert fringes.
 
The lifecycle of the mosquito that transmits malaria and the micro-organism that causes the disease are sensitive to high temperatures.
 
Some scientists have speculated that rising average temperatures may be making conditions more favourable for mosquitoes and pathogen development, leading to the surge in malaria cases.
 
However, a 2002 study found no significant rises in average temperature in the East African highlands where malaria is reaching epidemic proportions.
 
Therefore, some scientists dismiss the climate change-malaria link but the topic continued to be debated over the past four years.
 
“I did find evidence for an increase in temperature, which the authors of the previous paper said was not there,” Pascual said.
 
“We showed that a small increase in temperature can lead to a much larger increase in the abundance of mosquitoes,” she added.
 
“And because mosquito abundance is generally quite low in these highland regions, any increase in abundance can be an important factor in transmission of the disease.”
 
In the current study, the researchers looked only at the link between temperature and mosquito abundance, not at malaria statistics. 
 
The team plans to incorporate malaria data in future work to explore the interaction of various factors that may be affecting the spread of malaria.
 
"I think it's reasonable to assume that these factors are not independent," Pascual said.
 
The new study is expected to be published online this week in the Proceedings of the National Academy of Sciences.

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