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The West Nile Flood Has Slowed to a Trickle, But Health Officials Say Threat Hasn't Passed

Dallas was already having its worst-ever year for West Nile at the end of July, but things were only going to get worse, as August would prove to be the outbreak's worst month. The number of confirmed human cases in Dallas County jumped by 10 or 12 or 19 per day, and an average of two people were dying each week. It was then that the government declared a state of emergency and showered us with poison.

That all seems to be over. There are still new cases being reported -- three on Wednesday, two on Thursday, four on Friday -- but relatively few, and those are lagging indicators, since confirmation necessarily comes several days after a mosquito bite. The recent drop in temperatures gives another reason to be optimistic.

"Relatively speaking, as it gets cooler it slows down the metabolism of mosquitoes," said Dr. Christopher Perkins, Dallas County's medical director. Slower metabolism means the mosquitoes eat less, which means there is less chance of an infected mosquito biting a person.

There has been a steady decline, too, in the number of mosquito samples, collected from pools throughout the county, that test positive for the virus, something Perkins attributes to spraying and the application of adulticide as well as the coming end of mosquito season. Increased public awareness of the four D's -- draining standing water, dressing in mosquito-resistant clothing, using DEET, and staying inside at dusk and dawn -- has further aided the decline in cases, Perkins said.

There is, of course, a caveat. Sure, new human cases are on the decline, as are discoveries of infected mosquito pools, but this mosquito season has been freakish, Perkins said. A return to warmer temperatures or a good soaking of rain could prompt a temporary resurgence, though he won't say either way what he predicts will happen between now and the true end of the mosquito season in October.

"In all honesty, if I had that talent probably do something else," he said. "The chapter is still open."

If this year's skirmish isn't yet over, then neither is the war against West Nile. Across the country, the uptick in winter temperatures means mosquito activity rebounds more quickly come spring, which leads to more intense and more unpredictable epidemics -- and the climate certainly isn't getting any colder.


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