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 May was lower than average (368 requests compared to a five-year average of 351). In particular, mosquito-related requests continued to drop from a high in March, probably because many of the requests for mosquito control in early spring were seasonal non-biting midges emerging from lagoons and other waterways around the bay. Most categories were slightly…
2026 Mosquito SurveillanceAdult mosquito counts rose in June, particularly the species Culex erythrothorax, which has numbers about twice as high as average. This mosquito breeds in tule marshes and ponds and the high numbers are from sites in Mills Field, near the San Francisco airport. Technicians are working to access areas where it is difficult to apply pesticides because of thick vegetation surrounding standing water…
