A surge in tick activity is spreading Lyme disease, a potentially fatal illness, across the Bay Area. According to San Francisco State University biology professor Andrea Swei, average nymph densities are up 20-30% this year compared to last. Nymphs transmit diseases at higher rates than adult ticks.
The Western black-legged tick, found in California’s north coastal areas, is primarily responsible for Lyme disease transmission on the West Coast. The Bay Area Lyme Foundation has also reported a similar increase in regional tick activity, particularly in chaparral areas and woodland habitats.
Experts recommend taking precautions when outdoors: wearing white clothing to make ticks more visible, performing daily tick checks, and being vigilant about symptoms. Pets are often the first targets for ticks.
If you encounter a tick on your body, remove it promptly by using tweezers between your skin and the tick’s mouth and gently tugging. Never squish the tick; instead, flush it down the toilet to prevent disease transmission within hours of attachment.
Source: https://www.axios.com/local/san-francisco/2025/06/19/tick-activity-summer-bay-area