West Nile Virus Found in Mosquito Samples
Published on July 11, 2025
West Nile Virus Found in Mosquito Samples from Multiple Allegheny County Neighborhoods
PITTSBURGH –Mosquitoes collected by the Allegheny County Health Department’s (ACHD) Vector Control Program on July 8, 2025, in six areas tested positive for West Nile Virus. Those areas include Wilkinsburg, Schenley Park, Mt. Washington, Beltzhoover, Mt. Oliver, and Hazelwood.
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 Spring and continues through Fall. The last reported human case of West Nile Virus occurred about one year ago.
“Generally, the species of mosquitoes that carry West Nile Virus are active from dusk to dawn,” explained ACHD Vector Control Specialist Nicholas Baldauf. “Residents can prevent mosquito bites by using insect repellent on exposed skin or choosing to wear long sleeves and pants. Both methods are effective at reducing or eliminating the possibility of getting a mosquito bite.”
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 a headache, body aches, joint pains, vomiting diarrhea, or rash. Less than one percent of infected people develop serious illness.
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.
“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 ACHD’s Housing and Community Environment Program by completing its online form or calling 412-350-4046.
The Allegheny County Health Department’s Vector Control Program uses larvicide every spring to treat wetlands and catch basins known to be breeding sites throughout the county. The Health Department will continue to set mosquito traps as part of its ongoing vector-borne disease surveillance efforts. Surveillance efforts involve staff trapping mosquitoes to monitor the spread of West Nile Virus and other viruses that can infect people and animals. These efforts are an effective tool for quantifying the risk of human transmission of mosquito borne diseases, as well as informing ACHD decisions regarding the need for and timing of intervention activities, such as nighttime mosquito spraying.
Learn more about what ACHD is doing about public health vectors: Pest Control - Allegheny County, PA
For more information on West Nile Virus, including frequently asked questions about prevention, symptoms, and transmission, visit the CDC’s West Nile Virus webpage.
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