The number of cases of Lyme disease in the U.S. is growing, with Maine particularly being hard hit.

That's according to FAIR Health, a nonprofit that analyzes private health insurance for consumers. FAIR Health released new data suggesting private insurance claims related to Lyme disease have increased over the past 15 years, and claims in Maine went up in 2021.

“The top states in 2021, from highest to lowest, were New Jersey, Vermont, Maine, Rhode Island and Connecticut,” the nonprofit announced in a statement. “Maine, which was not previously on the list of top five states for Lyme disease claim lines, assumed third place in 2021, suggesting a growing presence of the tick-borne illness in the state.”

FAIR did not provide a specific number of cases in Maine in its announcement. However, according to the U.S. Centers for Disease Control and Prevention, there were 1,629 confirmed cases of Lyme disease in Maine in 2019, the last year data was available. That’s an increase of over 1,000 since 2010.

Lyme disease is caused by bacteria transmitted to a person through deer tick bites, according to the Maine Center for Disease Control and Prevention. Often, the appearance of a rash is an early sign of infection.

Symptoms include fever, headache, joint and muscle pain and fatigue, according to Maine CDC, but the disease is rarely if ever fatal and is usually treated with antibiotics.

FAIR Health began releasing data on claims associated with the disease in 2017. The current data is based on information related to more than 36 billion private health care claims studied over the past 15 years.