Malaria parasites develop faster in mosquitoes at lower temperatures than previously thought, according to researchers at Penn State and the University of Exeter. The findings suggest that even slight climate warming could increase malaria risk to hundreds of thousands, if not millions, of people — including travelers — in areas that are currently too cold for malaria parasites to complete their development.
"The rate of malaria transmission to humans is strongly determined by the time it takes for the parasites to develop in the mosquito," said Matthew Thomas, professor and Huck scholar in ecological entomology, Penn State. "The quicker the parasites develop, the greater the chance that the mosquito will survive long enough for the parasites to complete their development and be transmitted to humans."
According to Thomas, previous work suggested that in cooler temperatures malaria parasites developed too slowly to be transmitted to people during mosquitoes' lifetimes. That work, he said, was conducted almost 100 years ago using a Russian species of mosquito.
"Our study is the first since the 1930s to investigate the relationship between temperature and malaria parasite development," said Thomas. "Our results challenge this long-standing model in malaria biology."
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Image: The researchers used two of the most important malaria-hosting mosquito species in the world — Anopheles stephensi and Anopheles gambiae — to conduct their experiments. They maintained these malaria-infected mosquitoes in the laboratory under a variety of temperatures ranging from 16 to 20 degrees Celsius, or 60 to 68 degrees Fahrenheit. IMAGE: © Jim Gathany / CDC / Malaria Atlas Project