The Heat Is Online

Climate Change Propels the Spread of Infectious Disease

Warming accelerates the breeding rates of disease-bearing insects. It is also propelling them to altitudes and latitudes which were only a few years ago too cold to support their survival. Dr. Paul Epstein of Harvard Medical School reports that mosquitoes that previously could survive no higher than 1,000 meters are not being found at sites as high as 2,200 and even 3,200 meters. And they are spreading malaria, dengue and Yellow Fever to populations which have never previously been exposed and have no traditional immunity against them. At current rates of warming, scientists estimate that mosquito-borne epidemics will double in the tropical regions and increase 100-fold in the temperate regions (where we live) -- leading to as many as 80 million new cases a year of malaria alone in the next century. Globally, the incidence of malaria has quadrupled in the last five years. The cholera epidemic of the early 1990s that infected 400,000 people just in Peru was triggered in large part by warming. And changes in the climate have promoted the emergence of a frequently lethal pulmonary virus in the southwest, the spread of a strain of Encephalitis and a striking increase in the Northeastern U.S. of tick-borne Lyme disease.

Citations: "Climate, Ecology, and Human Health," Paul R. Epstein, M.D.,M.P.H., Consequences, Vol. 3, No. 2, 1997. "Biological and Physical Signs of Climate Change: Focus on Mosquito-borne Diseases," Paul R. Epstein, Henry F. Diaz, Scott Elias, Georg Grabherr, Nicholas E. Graham, Willem J. M. Martens, Ellen Mosley-Thompson and Joel Susskind, Bulletin of the American Meteorological Society, Vol. 79, No. 3, March, 1998.


The Intergovernmental Panel on Climate Change concluded that there is “discernible evidence” that humans—through accelerating changes in multiple forcing factors—have begun to alter the earth's climate regime. Such conclusions are based primarily upon so-called “fingerprint” studies, namely the warming pattern in the midtroposphere in the Southern Hemisphere, the disproportionate rise in nighttime and winter temperatures, and the statistical increase in extreme weather events in many nations. All three aspects of climate change and climate variability have biological implications.Detection of climate change has also drawn upon data from glacial records that indicate a general retreat of tropical summit glaciers. Here the authors examine biological (plant and insect) data, glacial findings, and temperature records taken at high-elevation, mountainous regions. It is concluded that, at high elevations, the overall trends regarding glaciers, plants, insect range, and shifting isotherms show remarkable internal consistency, and that there is consistency between model projections and the ongoing changes. There are implications for public health as well as for developing an interdisciplinary approach to the detection of climate change.

"Potential impact of global climate change on malaria risk," Martens, W.J.M., Niessen, L.W., Rotmans, J., Jetten, T.H.,and McMichael, T.J. Environmental Health Perspectives, vol. 103, 1995. "Resurgence of a Deadly Disease," Ellen Ruppel Shell, The Atlantic Monthly, August, 1997. "Global Climate and Infectious Disease: The Cholera Paradigm," Rita R. Colwell, Science, Vol. 274, Dec. 20, 1996. "Linking Health Effects to Changes in Climate," The New York Times, Aug. 10, 1998.