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 August was lower than average (392 requests compared to a five-year average of 569). Yellowjackets and other wasp requests were the furthest below average (199 compared to a five-year average of 326) but it is still the most frequently requested service, as is typical in the summer. Mosquito and Mosquitofish related service requests were also much lower…
2026 Mosquito Surveillance Adult mosquito counts in August were near average, except for Culex erythrothorax, which declined in average per trap from July despite high numbers at Mills Field, near the San Francisco airport. This mosquito breeds in tule marshes and ponds. Technicians are working to access areas where it is difficult to apply pesticides because of thick vegetation surrounding standing water. The District is…
