Since June 28th, 13 mosquito pools infected with West Nile virus (WNV) have been identified throughout Philadelphia. Positive mosquito pools also have been detected in neighboring counties in Pennsylvania. 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, 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.). Targeted treatments to control adult mosquito populations will be applied to areas with WNV positive pools as needed.

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 view travel-related arboviral infections surveillance data.

2016 Philadelphia West Nile Virus Surveillance Update

Cumulative 2017 Surveillance Update Report:

Week 28 (07/09-07/15) 2017 Season (05/01-07/15)
Mosquito Pools Tested 118 550*
WNV Positive Pools 9 13
Humans Tested** 1 5
Human WNV Cases 0 0
*550 mosquito pools at 176 different mosquito trapping sites.
**Testing among case reports received by PDPH only

2017 Geographic Distribution of Positive Mosquito Pools and Human Cases:

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 Requirement:

  • 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

Updated: 07/21/17 5:00pm