Although there have been no human cases detected in western Pennsylvania, there has been a record-high number of mosquitoes carrying the deadly West Nile Virus (WNV). Allegheny County health officials reported 138 samples tested positive, which is nearly twice as many as last year and the highest number ever.
The samples were gathered during the period in the summer when humans are most vulnerable to the virus. Dr. Ron Voorhees, Acting Director of the Allegheny County Health Department, said the root of the problem actually comes from birds.
“The mosquitoes pick it up from birds and then if they’re infected, they can pass it onto people so, clearly there must be an upsurge in birds and it may be because it’s been low for a while, that over time there’s not an ongoing source of infection and the birds are getting less immune,” Voorhees said.
Nationally, 1,590 cases of WNV in humans have been reported with 66 resulting in death.
Voorhees said the majority of people will experience few to any symptoms if infected by the virus. “Eighty percent of people have no symptoms at all. Then, for the remaining twenty percent, almost all of those people will only have a mild—might have some fever, perhaps some body aches, nausea and vomiting, just like any other viral illness, and if they’re not seriously ill, they probably don’t even need to see a physician,” Voorhees said.
The numbers through the last week in August are the highest ever reported to the Centers for Disease Control and Prevention since the virus was first detected in the U.S. in 1999. More than 70 percent of this year’s cases came from Texas, South Dakota, Mississippi, Oklahoma, Louisiana, or Michigan.
Voorhees said efforts to prevent additional cases are already in place in Pennsylvania. “The Allegheny County Health Department has been working with the state division of Environmental Protection to try to reduce the number of mosquitoes overall.” Voorhees said. “So, we’ve been treating catch basins to try to reduce mosquito breeding, and that will reduce the number of bites.”
A fact sheet with information about symptoms, prevention, and treatment can be found on the Allegheny County Health Department’s website.