Reports of common tick-borne diseases in Maine broke records again in 2025 as tick populations have expanded in the state.
Known cases of Lyme disease, anaplasmosis and babesiosis all exceeded report numbers from 2024, which broke records from the year before, according to state data. These illnesses, transmitted by the bites of infected ticks, can cause chronic health problems for some. Several Mainers have died from tick-borne illnesses in recent years.
As of Dec. 23, Maine had seen 3,611 reported cases of Lyme disease, up from 3,218 last year. Anaplasmosis numbers rose to 1,598 from 1,284. Babesiosis reports totalled 349 compared to 309 in 2024. Those numbers could still change before year’s end.
The Lyme reports were concentrated in Hancock, Knox, Lincoln and Waldo counties, with higher rates of anaplasmosis in the same region. A report by University of Maine researchers found earlier this year that the state’s midcoast has become a new epicenter for the diseases as ticks spread from southern counties.
While Lyme disease has been a growing challenge to Mainers for years, the increased cases of the other two strains also reflect a trend that communities such as Islesboro have noticed recently.
In October, residents and the island’s nurse practitioner told the BDN that anaplasmosis and babesiosis – which can be harder to detect than Lyme with its signature bulls-eye – seemed to be a growing presence that they expected to see continue, along with the appearance of others like Powassan virus and hard-tick relapsing fever.
The island saw its first known case of babesiosis this year, and statewide, reports have doubled since 2023.
Warmer, wetter winters have helped ticks survive, stay active longer and reproduce more often, according to University of Maine research. That contributes to the spread of disease.
On the coast, winters are milder, habitat is abundant for wildlife that are hosts to ticks, dense deer populations are confined to a limited space and people spend lots of time outside, the university’s tick lab coordinator, Griffin Dill, told the BDN earlier this year.