Health Information Portal (HIP)

Introduction

On June 18th, the first mosquito pool infected with West Nile Virus (WNV) in Philadelphia for the 2025 season was collected in Northeast Philadelphia, near Pennypack Park. Positive mosquito pools are anticipated to be identified across the city in the coming weeks. No human cases have been reported in the City. While the number of human cases of WNV and location of outbreaks has varied by season across the country, identification of mosquitoes infected with WNV remains the best predictor of increased risk for human infection in a given location.

From May through October, PDPH, in collaboration with the PA Department of Environmental Protection, conducts mosquito management activities throughout Philadelphia, which entails surveillance and identification of mosquito pools, testing pools for WNV, and control activities (eliminating breeding sites, larviciding catch basins, ground spraying, etc.). Since May 2025, 30 mosquito larvicide treatment events have been conducted across Philadelphia.

Click here for more information on West Nile Virus and other arboviruses, including disease guidance and reporting information.

Click here to download the latest 2024 West Nile Virus report in a printable format.

West Nile Virus Mosquito and Human Case Surveillance, Philadelphia PA, Morbidity Week 25 and Cumulative 2025 Season Update

*154 mosquito pools at 52 different mosquito trapping sites
State and National WNV Activity Reports

• Pennsylvania Department of Health
• Centers for Disease Control and Prevention

Advise your patients to:

• Use insect repellent that contains DEET (≥20% to also prevent tick bites) or another EPA-approved repellent and reapply as directed.
• Regularly check and remove standing water outside their home (e.g., unused pools, tires).
• Keep well-fitted screens on windows and doors.
• Report mosquito problems and dead bird sightings to the PDPH Vector Control Program’s Mosquito Complaint hotline at 215-685-9000.

WNV Testing and Reporting Requirements for Human Surveillance in Philadelphia:

• Collect serum and CSF for patients with unexplained encephalitis or meningitis. Absence of detectable antibodies in serum within 8 days does not exclude possible WNV.
• Report suspected and confirmed WNV infections and encephalitis cases to PDPH by telephone at 215-685-6741 during business hours or 215-686-4514 (press 1 for Unified Dispatch and ask for DDC on-call staff) after-hours, or fax at 215-238-6947.