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 September was lower than average (318 requests compared to a five-year average of 490). The total is lower than average, mostly because of the unusually low number of yellowjacket and wasp requests (109 compared to a five-year average of 254). However, yellowjackets remain the most frequently requested service, as is typical in the warmer season. It is…
2026 Mosquito SurveillanceAdult mosquito counts in September were near average. Culex pipiens was the most frequently collected mosquito species, followed closely by Culex erythrothorax. Both species prefer to feed on birds and can play a role in the West Nile virus transmission cycle. At times, they can transmit the virus to humans, particularly Culex pipiens, which is commonly found in residential neighborhoods. Culex…
