Excerpt from Boiling Point by Ross Gelbspan, plus links to reviews, author biography & more

'Mosquito-borne disorders are projected to become increasingly prevalent because their insect carriers, or 'vectors,' are very sensitive to meteorological conditions,' wrote Dr. Paul R. Epstein in the cover article of Scientific American. 'Cold can limit mosquitoes to seasons and regions where temperatures stay above certain minimums. Winter freezing kills many eggs, larvae and adults outright. Anopheles mosquitoes, which transmit malaria parasites, cause sustained outbreaks of malaria only where temperatures routinely exceed 60 degrees Fahrenheit. Similarly, Aedes aegypti mosquitoes, responsible for yellow fever and dengue fever, convey virus only where temperatures rarely fall below 50 degrees F.'

The problem is that there are very few areas of the planet that are cooling--and many, many areas where the temperature is rising.

Epstein, who is assistant director of the Center for Health and the Global Environment at Harvard Medical School, explained that 'mosquitoes proliferate faster and bite more as the air becomes warmer. At the same time, greater heat speeds the rate at which pathogens inside them reproduce and mature. At 68^oF, the immature P. falciparum parasite takes twenty-six days to develop fully, but at 77^oF, it takes only thirteen days. The Anopheles mosquitoes that spread this malaria parasite live only several weeks; warmer temperatures raise the odds that the parasites will mature in time for the mosquitoes to transfer the infection. As whole areas heat up, then, mosquitoes could expand into formerly forbidden territories, bringing illness with them. Further, warmer nighttime and winter temperatures may enable them to cause more disease for longer periods in the areas they already inhabit.'

Nor is it only warmer temperatures that propel the spread of insect-borne diseases. Weather extremes, another consequence of climate change, also play a pivotal role. 'Intensifying floods and droughts resulting from global warming can each help trigger outbreaks by creating breeding grounds for insects whose desiccated eggs remain viable and hatch in still water,' he wrote. As floods recede, he explained, they leave puddles that in times of drought become stagnant pools. As people in dry areas collect water in open containers, these can become incubators for new mosquitoes. The insects can flourish even more if climate change or other processes (such as habitat destruction) reduce the populations of predators that normally feed on mosquitoes.

One very troubling occurrence is that malaria had been declining in the United States before the recent rapid rise in global temperatures. As Epstein explained, 'Malaria is reappearing north and south of the tropics. The U.S. has long been home to Anopheles mosquitoes, and malaria circulated here decades ago. By the 1980s mosquito-control programs and other public health measures had restricted the disorder to California.'

'Since 1990, however, when the hottest decade on record began, outbreaks of locally transmitted malaria have occurred during hot spells in Texas, Florida, Georgia, Michigan, New Jersey, and New York (as well as in Toronto). These episodes undoubtedly started with a traveler or stowaway mosquito carrying malaria parasites. But the parasites clearly found friendly conditions in the U.S.--enough warmth and humidity, and plenty of mosquitoes able to transport them to victims who had not traveled. Malaria has returned to the Korean peninsula, parts of southern Europe and the former Soviet Union and to the coast of South Africa along the Indian Ocean,' Epstein reported.

It will also, scientists report, return to Great Britain. Last year, researchers at Britain's Durham University projected that if current temperature trends persist, the United Kingdom will begin to see recurring outbreaks of malaria in the next few decades.

From Boiling Point by Ross Gelbspan, pages 93-126 of the hardcover edition.  Reprinted with Permission from Basic Books – Copyright 2004.