A slight rise in temperature may increase the risk of malaria to hundreds of thousands, if not millions, of people, in areas that are currently too cold for malaria parasites to complete their development, according to a study.
Researchers at Penn State in the US 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.
“Our work shows that even small increases in temperature could dramatically increase malaria infections in humans because the parasites develop much faster at these lower temperatures than has been previously estimated,” said Jessica Waite, senior scientist at Penn State.
“Parasite development rate further increases when temperatures fluctuate naturally, from cooler at night to warmer in the day,” she said.
In addition, the team varied the daily temperatures by 10 degrees Celsius – 5 degrees Celsius above and below the daily mean – since such variation in temperature is common in natural settings when it is cooler at night and warmer in the daytime.
The traditional model estimates that parasites in the mosquito take 56 days to develop at temperatures just above the minimum threshold for development – a cool 18 degrees Celsius, or 64 degrees Fahrenheit.