West Nile Virus SurveillanceThe District’s West Nile virus surveillance program reports several types of positive West Nile virus results, including dead birds, mosquito samples (“pools”), sentinel chickens, and human cases.
Tick-borne disease pathogens in San Mateo CountyOver the past several years, staff have collected more than 30,000 ticks from around the County. Our laboratory staff identify and test these ticks for:
2025 Service RequestsOur staff were very busy helping with a variety of services, including mosquitoes, rodents, and ticks.
2025 Mosquito SurveillanceIn December, adult mosquito counts were very low, which is typical for this time of year. Culex pipiens was the most abundant mosquito in December, but numbers were slightly below average (1.63 per trap compared to a five-year average of 2.34). Aedes sierrensis and Aedes washinoi are two seasonal mosquitoes that weren’t detected at all in December. These mosquito species will likely be seen again…
