West Nile cases drop for 2nd year

One expert cites the wet weather as a factor.
ASSOCIATED PRESS
The number of West Nile virus cases in Ohio dropped for a second straight year, puzzling some health officials.
The state had only three confirmed infections in humans this year, down from 108 in 2003, according to the Ohio Department of Health.
The drop is even more dramatic when compared with 2002 when there were 441 confirmed cases.
The biggest difference among the last three years has been the weather.
Heavy rains followed by a summer-long drought in 2002 led to perfect breeding conditions for mosquitoes that help transmit the disease. But the past two years have been stormy and wet.
West Nile appears to infect people more during hot, dry years, said Robert Restifo, chief of the Health Department's vector-borne disease program.
Wet weather
He thinks that wet weather and more standing water spreads out the mosquito population. During dry weather, mosquitoes stay around the few wet spots, which increases the chances for disease to spread, he said.
But Restifo said that's just his theory.
Less than 1 percent of mosquitoes carry the West Nile virus and fewer than 1 percent of the people bitten by a mosquito will become severely ill. People older than 50 and those with health problems are considered to be most at risk.
This year, states in the West were hardest hit. California and Arizona each had more than 300 human cases.
Still in area
Some health officials in Ohio are puzzled.
"Our ability to predict has been thrown out the window," said Konni Sutfield, who oversees West Nile prevention efforts for the Toledo-Lucas County health department. "I can't figure it out."
Lee Mitchell, a biologist with the Toledo Area Sanitary District, was surprised at the drop in human cases because the virus is still in the area.
Tests of birds and mosquitoes have shown the virus is around, he said. It's also possible that West Nile might follow the path of another mosquito-borne disease, St. Louis encephalitis.
That disease spread through the state in 1975, infecting more than 400 people and killing 29. But after that, few cases emerged, and the last human case was in the mid-1980s.