Dead crows in Menlo Park have tested positive for West Nile virus

Published on August 03, 2026

Since June 2026, five dead crows in Menlo Park have tested positive for West Nile virus. When a crow tests positive for West Nile Virus, the San Mateo County Mosquito and Vector Control District sets additional mosquito traps in the area. At this time, no West Nile virus positive mosquitoes have been detected in the nearby area. Because crows can travel long distances, a crow that tests positive for West Nile virus does not necessarily indicate an increased risk for Menlo Park community members at this time.   

The San Mateo County Mosquito and Vector Control District encourages you to protect yourself and others against West Nile virus by following the safe practices below: 

• Wear long-sleeved shirts and long pants, especially in the early morning, evening and night when mosquitoes are most active.
• Dump standing water so mosquitoes can’t grow.
• Protect yourself from mosquito bites. Use an EPA-registered insect repellent. Learn more about insect repellent.
• Check and repair broken screens on windows and doors to keep mosquitoes out of your house.
• Report biting mosquitoes – San Mateo County Mosquito and Vector Control District staff will check the neighborhood for standing water and work to stop the mosquito breeding. Report biting mosquitoes by calling 650-344-8592 or submitting a request online.
• Report dead birds to help track West Nile virus using the online reporting portal.

Learn more about West Nile virus.