Tick Surveillance

The District collects ticks from around the County and tests for several tick-borne diseases, including Borrelia burgdorferi, which causes Lyme disease, and Borrelia miyamotoi, which causes a similar, less-common tick-borne disease.

The results of these tests are reported as the minimum infection prevalence, or MIP. This is a way of describing the proportion of ticks tested that are infected with a particular pathogen. MIP is typically reported for each park surveyed (with the exception of parks where there were not enough ticks collected to complete testing), and for the parks as a whole.

A MIP of 2-3% is considered normal for our county, and does not indicate an elevated level of risk.

For more information on how the District collects ticks for disease surveillance, visit the Tick Control and Monitoring page.

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Tick Surveillance, Water Year 2022-2023

Laboratory staff continued winter surveillance for adult Ixodes pacificus (Western black-legged ticks) in February. Ticks are collected by dragging a one-meter square sheet of white flannel over the vegetation alongside trails; a technique called “flagging.” Ixodes pacificus ticks will be tested for the presence of Borrelia burgdorferi (the causative agent of Lyme disease), as well as Borrelia…

Person in tan uniform walking away from the camera down a wooded trail. The person is holding out a stick that has a square white cloth about 3ft tall by 3ft wide on it. The cloth is being dragged over the vegetation along the edge of the trail.

Tick Surveillance for Water Year 2021-2022

During May, laboratory staff focused on surveillance of nymphal Ixodes pacificus, Western black-legged ticks. Tick nymphs are more difficult to collect than adults because they don’t quest on vegetation along trails. Instead, they are found on tree stumps, downed longs, rocks, and in leaf litter. Areas that were surveyed in May were Big Canyon Park in San Carlos, and Pescadero Marsh and Butano…

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Tick Surveillance, Water Year 2020-2021

The San Mateo County Mosquito and Vector Control District conducts annual tick collection and molecular testing via real-time PCR analysis for the pathogens that cause Lyme disease, hard-tick relapsing fever, and human granulocytic anaplasmosis (HGA). All three diseases may be vectored by both nymphal and adult black-legged ticks (Ixodes pacificus). In the 2020-2021 water year, a total of 4,728…

Tick Surveillance, 2019-2020 Water Year

During February 2020, laboratory staff continued surveillance for adult Ixodes pacificus (Western black-legged ticks). Ticks are collected by dragging a 1 meter square sheet of white flannel over the vegetation alongside trails. Ixodes pacificus ticks will be tested for the presence of bacteria Borrelia burgdorferi, the causative agent of Lyme disease, as well as Borrelia miyamotoi and Anaplasma…

Large area of green grass, with 10 people surrounding a picnic table looking at small items

Tick Surveillance, 2018-2019 Water Year

Every year the District collects ticks from recreational areas in the county to assess the risk of tick-borne disease. One way to measure this is by determining the minimum infection prevalence (MIP), which estimates what percentage of these ticks are expected to be carrying a given disease agent in a population.

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