CDC: Worst Year Ever for West Nile Virus in U.S.

New numbers from the Centers for Disease Control and Prevention confirm that the recent West Nile virus outbreak is the largest ever in the United States. 

CNN is reporting the number of cases so far this year is the highest recorded through August since the disease was first detected in the United States in 1999. As of Tuesday, 38 states had reported human infections.

"Here in Pennsylvania, there've already been some human cases," said Guillermo Cole, Allegheny County Health Department spokesman.

Cole said, though, none of the approximately eight cases have been from western Pennsylvania. Since 2002, when the first case appeared here, there have been 21 humans infected and "a few deaths," he said. There was one human case reported last year.

"This is the time of year for human cases," Cole said.

The cases reported to the CDC as of Tuesday total 1,118, including 41 deaths. That number rose to 42 on Wednesday when a death was reported in Arkansas, according to the CNN report.

About 75 percent of the cases are in Mississippi, Louisiana, South Dakota and Oklahoma, with Texas at the epicenter of the outbreak. Texas has 586 confirmed cases and 21 deaths, according to the Texas Department of State Health Services.

This year, Cole said Allegheny County has 121 mosquito samples that tested positive for the virus.

"That's the most we ever had," he said.

He attributes the increase to the mild winter, early spring, hot weather during early summer and the intermittent rains this month.

Prior to this year, the most—72—were recorded last year, compared to the 58 when the health department began sampling mosquitoes in 2002. Cole said infected mosquitoes are more likely to be found in the city than the suburbs.

The health department has sprayed in neighborhoods where infected mosquitoes have been found. The East End, and Wilkinsburg were sprayed to kill larva on July 17 and 31, and the West End on July 25.

On Aug. 7, the health department and state Department of Environmental Protection teamed up to killl adult mosquitos in the South Side and Mt. Washington with Zenivex, a pesticide that Cole said is safe for people and pets. Zenivex is distributed through a truck-mounted, ultra-low volume spray at a rate of one to three-ounces an acre.

Last week, the two agencies, in a joint effort, sprayed in the Morningside and Highland Park areas. Thursday, this week, the Bloomfield/East Busway area will be sprayed between 8 and 11 p.m.

Cole said most people who are bitten by infected mosquitoes will not get sick. The few who do might feel like they have influenza, with a fever, headache, body aches, rash and swollen glands.

Fewer than 1 percent of those infected will develop West Nile encephalitis, which usually affects mostly elderly persons and those with weakened immune systems. Cole suggests that those in the high-risk group contact their health care provider if they develop any of the symptoms of West Nile virus.

The CDC offers a West Nile virus information page to answer many questions people have about the illness.

Cole said the health department urges the public to take the following steps to prevent infection:

• Remove standing water (tires, bird baths, containers)
• Use an insect repellent
• Minimize the amount of exposed skin
• Cut down on the time spent outdoors, particularly from dusk to dawn.