Overview: West Nile virus case in Greater Sudbury
Public Health Sudbury & Districts has confirmed a West Nile virus (WNV) positive horse in the Greater Sudbury area. This marks another animal case in the region for 2025, following two crows confirmed with WNV earlier in the season. The last time a person tested positive within the area was in 2023. While this news is noteworthy, health officials stress that the overall risk to people remains low, especially with continued preventative measures as late summer and early fall bring higher mosquito activity.
Why the One Health approach matters
The situation illustrates the One Health concept, which links human, animal, and environmental health. By tracking WNV across humans, animals, and mosquitoes, public health authorities, veterinarians, environmental experts, and healthcare providers can better predict, prevent, and control outbreaks. Ontario’s approach emphasizes collaboration across sectors to reduce risk and respond quickly when cases arise.
How West Nile virus spreads and what it means for people
WNV is transmitted through the bite of an infected mosquito. It cannot be passed directly from horses to humans or between other animals. Most people infected with WNV have no symptoms. When symptoms do occur, they can include fever, headache, body aches, mild rash, and swollen lymph glands. In very rare cases, the virus can affect the brain and cause severe illness. The presence of an infected horse signals that mosquitoes in the area are capable of carrying the virus, underscoring the importance of mosquito protection for everyone, especially during late summer and early fall.
What this means for horse owners
Early signs of WNV in horses include fever, muscle twitching, hypersensitivity to touch or sound, and difficulty standing. Vaccination remains the most effective defense for horses. Owners should ensure vaccines and boosters are up to date and follow veterinary guidance on prevention and mosquito control around barns and pastures.
Practical prevention steps for residents and property owners
Public health authorities offer practical measures to reduce the risk of West Nile virus for people and animals:
- Reduce mosquito breeding sites around homes by removing standing water and ensuring proper drainage.
- Keep windows and doors screened with well-fitting screens to prevent indoor entry of mosquitoes.
- Avoid outdoor activities at dusk and dawn when mosquitoes are most active.
- Dress in light-colored, long-sleeved clothing when outside and wear an approved insect repellent as directed on the label.
- For horse owners, stable horses at dawn and dusk, consider using fans in barns, and apply veterinarian-approved repellents as recommended.
Where to find more information
For more information about West Nile virus and current local guidance, please contact Public Health Sudbury & Districts at 705.522.9200 (toll-free 1.866.522.9200) or visit phsd.ca. For horse-specific concerns, veterinarians and animal-health resources can provide tailored advice and vaccination recommendations.
Notes from public health officials
Public Health Sudbury & Districts’ spokeswoman emphasized that ongoing vigilance is essential. “Although the overall risk of a person becoming infected remains low, late summer and early fall are typically the time of greatest risk for contracting West Nile virus as mosquitoes can carry higher levels of the virus at this time of year,” said Jonathan Groulx, manager of the Health Protection division. The One Health framework continues to guide coordinated monitoring and response across human health, animal health, and the environment.
For updates on West Nile virus in the region and guidance on protection strategies, residents are encouraged to stay informed through Public Health Sudbury & Districts communications and phsd.ca.
