warming had caused malaria to spread

WHO report in 2000 found that warming had caused malaria to spread from three districts in western Kenya to 13 and led to epidemics of the disease in Rwanda and Tanzania. In Sweden, cases of tick-borne encephalitis have risen in direct correlation to warmer winters. Asian tiger mosquitoes, the type that carry dengue fever, have been reported recently as far north as the Netherlands.

Culex pipiens is a favored carrier of a disease first identified in a feverish woman in the West Nile district of Uganda in 1937.

The disease was found again in Israel in the 1950s and in Romania in 1996. Each outbreak followed an unusual dry, hot spell, typical of adverse weather becoming more frequent as a result of climate change, researchers at the University of Haifa in Israel concluded.

In 1999, the virus landed in New York, probably at LaGuardia Airport. Disease sleuths speculate it was lurking in a mosquito stowaway or in the bloodstream of someone already infected. That summer also brought unusually hot, arid weather to New York.

Before the year had ended, 62 people had been infected and seven had died. The next two years were more temperate, but the disease exploded across the United States and into Canada when another hot, dry summer hit in 2002.

Susan Harrison, then 45, prepared a Labor Day barbecue that year with her husband and two daughters on the deck of their Toronto home. She was bitten by a mosquito, but shrugged it off.

In a few days, she felt a shooting pain in her legs. Within two weeks, she could not get out of bed. She was put on a respirator and spent three months in intensive care. She now uses a wheelchair, her legs and right arm paralyzed by West Nile virus.