stagnant pools of water. According to several prominent scientists,
drought is the key factor in spreading West Nile virus. Outbreaks
require an unfortunate series of events, they say. According to Dr.
Dickson Despommier, a professor of public health at Columbia
University, the mosquitoes’ favorite prey is birds, but periods of high
heat and drought send such common urban-dwelling species as crows,
blue jays, and robins out of the city in search of freshwater. City bird
populations are further reduced as unlucky individuals are bitten and
killed by West Nile infection.
“By reproductive imperative the mosquitoes are forced to feed on
humans, and that’s what triggered the 1999 epidemic,” Dr.
Despommier says. “Higher temperatures also trigger increased mos-
quito biting frequency. The first big rains after the drought created new
breeding sites.” It took Hurricane Floyd, which passed through New
York on September 16, to break the weather cycle that led to the out-
break.
Dr. Despommier says this same pattern is also discernible in
recent West Nile outbreaks in Israel, South Africa, and Romania. In
Bucharest, Dr. Despommier’s investigation turned up abandoned
buildings whose basements were full of water, a perfect culexbreeding
ground.
Another prominent proponent of the West Nile global warming
connection is Dr. Paul Epstein of Harvard University. “Droughts are
more common and prolonged as the planet warms,” he says. “Warm
winters intensify drought because there’s a reduced spring runoff. The
cycle seems to rev up in the spring, as catch basin water dries up and
what’s left becomes organically rich and a perfect mosquito breeding
place. The drought also reduces populations of mosquito predators.”
In 2002, the West Nile spread across the country, appearing in
forty-four states and the District of Columbia. Five provinces of Canada
were also affected. In a growing scientific consensus, public health offi-
cials believe the next drought will give this serious virus an even wider
reach. Spraying certainly has not stopped these infectious bugs.
Researchers at France’s University of Montpellier said in mid-2003
that a mutation in the West Nile mosquitoes’ genetic code resulted in
their singular resistance to pesticides.
46 Jim Motavalli with Sherry Barnes