Daily temperature fluctuations affect malaria transmission potential
Most climate-based malaria transmission models utilize mean monthly temperatures to explore the impact of climate on infection dynamics. According to CIDD researchers, this leads to an overestimation of malaria transmission in higher temperature areas and underestimation of transmission in lower temperature areas. Their studies show that daily temperature fluctuations greatly influence the incubation period of parasites in their vector, which alters malaria transmission potential.
Published: 2009
Author(s): Paaijmans KP, Read AF, & Thomas MB
Title: Understanding the link between malaria risk and climate
Journal: Proceedings of the National Academy of Sciences of the United States of America 33: 13844-13849
Adaptation of a picture from the Public Health Image Library taken by James Gathany.
According to the World Health Organization, malaria infects 300-500 million individuals worldwide and is responsible for more than a million fatalities annually. A variety of forces, including socioeconomic and environmental factors, heavily influence this pathogen’s disease dynamics. Since the growth of malaria parasites is extremely temperature sensitive and the global climate appears to be changing, malaria transmission models have increasingly focused on temperature.
Krijn Paaijmans, a CIDD postdoc, and professors Andrew Read and Matthew Thomas have examined the impact of daily temperature fluctuations on malaria parasite development. They found that under cooler conditions these fluctuations increase the rate of parasite development. However, under warmer conditions, diurnal temperature variations slow the parasite’s growth. These data suggest that models using average monthly temperature may be overestimating transmission in warmer climates and underestimating transmission in cooler climates.
The thermodynamic model was validated by using 17 years of daily temperature data from the Kenyan Highlands district of Kericho, an area with a cool climate and regular malaria epidemics. Only when daily temperature fluctuations were incorporated into the model could these epidemics be explained.
This work emphasizes the importance of including daily temperature fluctuation when modeling malaria epidemic potential. Additionally, including such data appears essential for accurately predicting changes in disease epidemics that may occur as a result of global climate change.
