But the cosmopolitan virus does raise questions about the globalization of epidemics, and some analysts believe climate change may be having an effect on the spread of such diseases. "You could never with any certainty tie a disease of this type to global warming," says Gorman. "But there’s an argument being made that climate change may change patterns of disease –- some plant and animal forms are certainly occurring further north than we’ve ever seen them before." Not much comfort to beleaguered New Yorkers suffering almost nightly pesticide bombardment from the mayor’s helicopters. And if climate change is a factor, the anti-mosquito crusade could be just the first of a bizarre set of epidemiological battles over the coming decades.
New York City mayor Rudy Giuliani’s epic struggle with killer mosquitoes just took a nasty twist. It turns out that the encephalitis outbreak that has killed three New Yorkers may involve a version of the virus never before seen in the Western Hemisphere. The Centers for Disease Control and Prevention said Monday that its review of the outbreak –- identified at first as St. Louis encephalitis –- has determined that at least one of the deaths was caused by the West Nile virus, found only in Africa and Asia. Like the St. Louis version, the virus is carried by birds and transfers to humans via mosquito bites. "Although it’s never been identified as a cause of disease here, that may be because it wasn’t specifically checked," says TIME medical correspondent Christine Gorman. "And, of course, encephalitis would be treated the same way no matter which virus had caused it."