Lyme disease cases in Michigan jump to nearly 3,400 in 2025, compared to under 2,300 in prior 3 years

Michigan residents are increasingly at risk for acquiring Lyme disease, data from the Michigan Department of Health and Human Services shows. 

The latest Michigan Disease Surveillance System report, which includes data from the most recent four weeks in addition to previous annual data, states there were 21 Lyme disease cases in the most recently reported week, with a total of 72 in the most recent four weeks and 246 so far this year.  

But winter is the off-season in Michigan for black-legged ticks, which are most active from March to November. 

For a year-by-year perspective, state officials said there were 3,379 such cases during 2025, a noticeable increase from the previous three years, which were all less than 2,300 a year. 

Lyme disease is carried by the blacklegged tick, more specifically, a bacterium that the tick carries, that is called Borrelia burgdorferi. State officials say it is considered the most commonly reported vector-borne disease in the United States and is increasingly occurring in Michigan. 

Most of Michigan's counties are considered to have a "known risk" of Lyme disease with at least two confirmed local exposures or ticks known to be infected with the bacteria involved. This list, updated in March 2026, includes nearly all of Southeast Michigan, with only Monroe County shown to have a lesser "potential risk." 

Symptoms of Lyme disease include flu-like symptoms, although it can also affect the joints, heart and nervous system. Most cases are treated successfully with antibiotics, state officials said. 

"Finding and removing ticks promptly can prevent Lyme disease," state officials said.