A new study from Marshfield Clinic researchers is raising concerns about the prevalence of Lyme disease in Wisconsin’s tick population.
Scientists found that more than 50 percent of deer ticks tested in the state are carrying Borrelia burgdorferi, the bacterium that causes Lyme disease. The research was conducted in the spring of 2024 and analyzed thousands of ticks collected across Wisconsin. Staff Scientist Dr. Alexandra Linz says the findings, while not unprecedented, were higher than expected.
“It’s not the highest number ever reported in Wisconsin, but it is up there,” Linz said. “It was higher than we were expecting to see. I will say that 51% does not mean that your risk of getting Lyme disease after a tick bite is 51%. It’s much lower than that.”
Researchers collected more than 12,000 ticks over the course of the study, with adult female deer ticks showing particularly high infection rates. Despite the findings, Linz emphasizes that a tick bite does not automatically lead to Lyme disease. Still, the data highlights the importance of prevention — especially as people spend more time outdoors during warmer months.
Experts recommend avoiding tick-prone areas like tall grass and brush whenever possible. Wearing long pants, long sleeves, and tucking clothing in can help create a barrier against ticks. Insect repellents containing DEET or permethrin are also effective tools. After outdoor activity, Linz says it’s important to check thoroughly for ticks.
“After you’re done with your activity, making sure to do a tick check — showering can be helpful too,” Linz said. “Really checking places ticks like to hide, like the hairline or armpits. It can be helpful to have a buddy check your back for you.”
Marshfield Clinic researchers say they have been monitoring Wisconsin’s tick population since 2024 and plan to continue tracking trends to better understand the risks and inform public health guidance.