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 SurveillanceIn May, adult mosquito counts for the six most frequently collected species averaged below five per trap, which is typical for the month. Collection levels of Aedes washinoi dropped from April, from 9.3 to 5.0 mosquitoes per trap as water sources in Mills Field were successfully controlled or dried up. Culex pipiens and Culiseta incidens had a seasonal rise in abundance from April to May but…
