Data and Statistics

California Department of Public Health Vector Borne Disease Annual Report, 2023

West Nile Virus Surveillance

The 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.

Computer generated image of the filled-in outline of San Mateo County. There are dozens of little red pins all over the map.

Tick-borne disease pathogens in San Mateo County

Over 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:

A person holding a red trap device for disease surveillance hanging from a tree branch.

2025 Service Requests

Our staff were very busy helping with a variety of services, including mosquitoes, rodents, and ticks.

Numerous small insects on a window screen.

2025 Mosquito Surveillance

In February, adult mosquito counts of all species were very low, which is typical for winter months. We expect to see a rise in adult mosquito population levels in the spring.

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