For the second year in a row, Maine recorded a record number of Lyme disease cases in 2023, continuing a long-term trend of the deer tick-borne infection increasing in the state.
Lyme cases jumped from 2,617 in 2022 to 2,904 cases last year, according to the Maine Center for Disease Control and Prevention. Cases were most prevalent in the Midcoast and Down East regions, with Knox County having the highest concentration of Lyme disease, at 661 cases per 100,000 population. Waldo, Hancock and Lincoln counties also had among the highest levels of Lyme disease, while Cumberland County, the state’s most populous, recorded 123 cases per 100,000 population.
Griffin Dill, integrated pest management professional for the University of Maine Cooperative Extension’s tick lab, said the range of the deer tick is expanding, and tick populations are now firmly established in the Midcoast and Down East.
“The focal point of tick-borne disease has been shifting from Cumberland and York counties to along the Midcoast and Down East,” Dill said.
Why Lyme disease cases are most concentrated farther down the coast is unclear, Dill said, but with its humid, coastal climate, the “Midcoast area is highly conducive for ticks and their wildlife hosts.”
Dill said that although research shows climate change is contributing to the deer tick expanding its range, it’s difficult to conclude that climate change played a large role in the greater prevalence of Lyme disease in the Midcoast.
“The conditions (in the Midcoast and Down East) were probably always somewhat favorable, but the ticks hadn’t made it there yet,” Dill said. “Now that they’ve arrived, they’re thriving, and that’s allowed their populations to expand.”
Overall weather conditions in Maine also may have contributed to the record number of Lyme cases in 2023, including a lot of rain in the late spring and summer, and warmer conditions in fall and winter.
Also, submissions to the tick lab in 2023 changed with more ticks in the nymph stage being sent in, from about 15% of all submissions to 30%, Dill said. People send in dead ticks to the tick lab for identification and to test for pathogens.
Dill said ticks in the nymph stage are less likely to carry the bacteria that causes Lyme disease than adult ticks, but are much harder to detect on the human body. Dill said that means nymph ticks are more likely to be attached to the host long enough to transmit Lyme disease. A tick needs to be attached for at least 36-48 hours in most cases before being able to transmit Lyme disease, according to the U.S. CDC.
Symptoms of Lyme disease include a bull’s-eye rash, fever, headache, joint pain and fatigue. The rash is not always present. If caught early, Lyme disease can be treated with antibiotics.
While Lyme set a new record, the other two most prevalent tick-borne diseases in Maine – anaplasmosis and babesiosis – experienced slight downturns last year, although long-term trends are still showing higher numbers of those diseases.
Maine logged 744 cases of anaplasmosis, down from 824 in 2022, and 188 cases of babesiosis, a slight reduction from 192 in 2022. Anaplasmosis is caused by a bacterial infection while babesiosis is caused by microscopic parasites.
Research about ticks is ongoing, and the University of Maine was recently awarded $6.2 million in federal funding to research ways to control tick populations, identify emerging tick species and expand public health efforts.
Lindsay Hammes, spokesperson for the Maine CDC, said “education for the public about the prevalence and risks of ticks has been, and continues to be, a top priority for the Maine CDC.”
Hammes said the Maine CDC is “reminding the provider community to consider tick-borne diseases for patients presenting with relevant symptoms has been another key to our approach in helping to combat tick-borne diseases across Maine.”
To help prevent tick-borne diseases, wear long pants and long sleeves when in the woods or raking leaves, use insect repellant and conduct tick checks on your body after spending time in tick habitat.
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