Health Dept: Additional Mosquito Samples Test Positive West Nile Virus
Published on July 21, 2025
Allegheny County Health Department Announces Additional Mosquito Samples Test Positive for West Nile Virus; Seven Neighborhoods to be Sprayed on July 24
PITTSBURGH – Allegheny County Health Department today announced additional mosquito samples have tested positive for West Nile Virus. Accordingly, the health department will treat areas for mosquitoes in the communities of Hazelwood, South Side Slopes, Arlington, Mt. Oliver, Carrick, Knoxville, and Beltzhoover with a pesticide called Zenivex E20. Zenivex E20 is classified by the EPA as a low-risk insecticide as it is not harmful to humans or pets.
Crews will use a truck mounted Ultra Low Volume (ULV) sprayer on Thursday July 24th, from 8 pm to 11 pm, to lower the local mosquito population and minimize the risk of human transmission. In the event of rain, spraying will take place the following Monday, July 28th, during those same hours.
West Nile Virus is the leading mosquito-borne disease in the United States. It is spread to people by bites from infected mosquitoes. Cases of West Nile Virus occur during mosquito season, which starts in the spring and continues through the fall. The last reported human case of West Nile Virus in Allegheny County occurred in September 2024.
Most people infected with West Nile Virus do not feel sick. Only one in five people infected with the virus develop a fever and other symptoms, such as headache, body aches, joint pains, vomiting, diarrhea, or rash. Less than one percent of infected people develops serious illness.
“Generally, the species of mosquitoes that carry West Nile Virus are active from dusk to dawn,” said Allegheny County Health Department Vector Control Specialist Nicholas Baldauf. “To deter mosquito bites, we encourage people to use insect repellent on exposed skin or to wear long sleeves and pants. Both methods are effective at reducing or eliminating the possibility of getting a mosquito bite.”
There are no vaccines to prevent or medications to treat West Nile Virus. Residents who believe they, or someone they know, have West Nile Virus should consult a health care provider for evaluation and diagnosis.
“Allegheny County residents play an important role when it comes to reducing the area’s mosquito population,” said Baldauf. “Mosquitoes can breed in as little as a half inch of stagnant water, so residents should pay close attention to potential breeding sites like stagnant water in tires, unused swimming pools, buckets, corrugated piping, and clogged gutters.”
Residents can report mosquito breeding sites on both private properties and public areas to the Allegheny County Health Department’s Housing and Community Environment Program by completing its online form or calling 412-350-4046. (https://alleghenycounty.govqa.us/WEBAPP/_rs/(S(vaeix3t0t3bnpmb0knm5jvwh))/supporthome.aspx/)
For more information on West Nile Virus, including frequently asked questions about prevention, symptoms, and transmission, visit the CDC’s West Nile Virus webpage. (https://www.cdc.gov/west-nile-virus/index.html)
Media inquiries may be directed to Ronnie Das,
Public Information Officer for the Health Department,
at ronnie.das@alleghenycounty.us or by phone at 412-578-7991.