Tick Collections from parks, 2025-2026 Season (November 2025 through May 2026)

Laboratory staff began winter surveillance for adult Ixodes pacificus (Western black-legged ticks) in November. 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 are tested for Borrelia burgdorferi (the causative agent of Lyme disease), as well as Borrelia miyamotoi (the agent of hard-tick relapsing fever) and Anaplasma phagocytophilum (the agent of granulocytic anaplasmosis).

This December, staff focused on tick inspections of residential properties as part of an ongoing project to evaluate the risk of tick exposure in yards. This season, staff continue to focus on the San Mateo Highlands neighborhood, west of the city of San Mateo and east of Interstate 280. During the month of December, fifteen yards were surveyed for ticks. Additional properties will be assessed throughout the winter.

Regular seasonal tick surveillance was also conducted in Coal Creek Open Space Preserve near Portola Valley, Wunderlich County Park in Woodside, Laurelwood Park in San Mateo, and Corte de Madera Creek in Woodside, near Portola Valley. Seasonal surveillance for adult ticks will continue through March.

Tick Collections from parks and neighborhoods, 2025-2026 Season (through December 2025)

 

Page last reviewed: January 7, 2026