Mosquitoes in 9 Louisville neighborhoods test positive for West Nile virus, officials report

Louisville mosquito surveillance has found West Nile virus in mosquitoes collected from nine neighborhoods, according to a report Tuesday from WLKY. The positive findings indicate that the virus is circulating locally and that additional testing is under way to track where it may be spreading over time.

The report says more mosquitoes tested positive than in prior rounds, extending the number of Louisville areas where West Nile virus has been detected. While West Nile virus can cause serious illness in people, officials monitor mosquito infection rates to assess risk and determine which areas need heightened public attention.

The mosquito collections were conducted as part of ongoing efforts to detect West Nile virus in the community before human cases appear. Health agencies typically rely on laboratory testing of trapped mosquitoes to estimate local virus activity, since the presence of infected mosquitoes can precede illness in residents.

West Nile virus risk varies by time and location, in part because mosquito populations change as weather shifts. By testing across multiple neighborhoods, the city can identify patterns in where infected mosquitoes are appearing and respond with targeted information to residents.

Public health officials have continued to collect mosquitoes and report findings as summer progresses, the WLKY report said. Additional testing is expected to continue in the coming days and weeks, with results used to inform future neighborhood-specific risk assessments.

The WLKY report did not indicate that spraying or other field interventions were being implemented in response to the new positive detections. Instead, the emphasis is on surveillance, reporting, and continuing efforts to understand how widespread West Nile virus activity is in Louisville.

Residents are generally reminded to protect themselves from mosquito bites during periods when infected mosquitoes are detected, particularly older adults and people with medical conditions that can increase the likelihood of severe illness. Local guidance for residents typically includes steps to reduce exposure to mosquitoes and eliminate standing water where mosquitoes breed.

The next published update is expected to follow the completion of additional mosquito collections and laboratory results, which will show whether the number of neighborhoods with positive tests continues to grow or stabilizes.