Climate change: Reduce or spread disease?

ANN ARBOR, Mich., April 6 (UPI) -- U.S. government scientists are disputing studies that predict climate change might expand the scope of human infectious diseases.

Kevin Lafferty of the U.S. Geological Survey and colleagues suggest that instead of an expansion of the global range of diseases, global warming might cause a poleward shift in areas suitable for diseases as higher latitudes become warmer and regions near the equator become too hot.

Lafferty says the newly suitable areas for diseases will tend to be in more affluent regions where medicines are in widespread use and can more readily combat the diseases.

"The dramatic contraction of malaria during a century of warming suggests that economic forces might be just as important as climate in determining pathogen ranges," Lafferty said.

Mercedes Pascual of the University of Michigan -- lead author of one of five papers published in response to Lafferty's research -- agrees disease expansion in some areas could be accompanied by retraction in others. But she said disease range doesn't always correlate with the number of humans infected.

"It would be very unfortunate if the conclusions in Lafferty's paper were taken as evidence that climate change does not matter to infectious diseases," Pascual said. "Range shifts will matter and should be better understood."

Both arguments appear in the April issue of the journal Ecology.