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:
2026 Service RequestsThe total number of service requests in January was a little lower than average (157 requests compared to a five-year average of 178). The two largest categories, rodents and mosquitoes, were both less frequent than most usual. Service requests often drop in winter when insects are less active and residents spend more time indoors.
2026 Mosquito SurveillanceIn January, adult mosquito counts were very low, which is typical for this time of year. Culex pipiens was the most abundant mosquito in January with numbers near average. Aedes washinoi is a seasonal mosquito that is often detected as larvae in freshwater marshes. This mosquito will typically peak in numbers in April but will sometimes fly in winter if there is a period of warm temperatures…
