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West Nile Virus

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One human West Nile Virus (WNV) case has been identified in Philadelphia during the 2022 season. The adult resident developed fever and was subsequently hospitalized. Positive mosquito pools continue to be identified across 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, the Philadelphia Department of Public Health (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 2022, 8 locations in Philadelphia have been treated to control adult mosquito populations.

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

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

Click here to download the 2021 season summary report of West Nile Virus in a printable format.

2022 Philadelphia West Nile Virus Mosquito and Human Case Surveillance

Week 30 (7/10 - 7/30)

2022 Season (5/1 - 7/30)

Mosquito Pools Tested*



WNV Positive Pools



Humans Tested**



Human WNV Cases



*424 mosquito pools at 97 different mosquito trapping sites

**Testing among case reports received by PDPH only

2022 Geographic Distribution of Positive Mosquito Pools and Human Cases


Advise your patients to:

  • Use repellent with DEET ( ≥ 20% to also prevent tick bites), Picaridin, or oil of lemon eucalyptus when outdoors.
  • 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 Line at 215-685-9000.

WNV Testing and Reporting Requirements for Human Surveillance in Philadelphia:

  • Collect CSF (from symptom onset--day 8) and serum (day 8--14) from patients with unexplained encephalitis or meningitis for WNV IgM testing.
  • Report suspected and confirmed WNV infections (neuroinvasive or non-neuroinvasive illness) and encephalitis cases to PDPH by telephone at 215-685-6742 (or 215-686-4514 after hours).
    • Reports also may be faxed to 215-238-6947.

State and National West Nile Virus Activity Reports