(NEXSTAR) – Lyme disease cases have jumped across the United States over the past 15 years, but especially in rural areas, a new study found.

Humans can get Lyme disease from the bite of an infected tick, according to the Centers for Disease Control and Prevention. Milder symptoms include fever headache, fever, fatigue and skin rash. Left untreated, however, Lyme disease can spread to joints, the heart and the nervous system.

From 2007 to 2021, private insurance claim lines involving Lyme disease diagnoses rose 357 percent in rural areas and 65 percent in urban areas, according to a recent study FAIR Health, a national nonprofit that tracks health care claims. A claim line is an individual service or procedure listed on an insurance claim.

In just the past five years, those numbers are 60 percent for rural areas and 19 percent for urban areas, the study found. There was a seasonal pattern as well, the study found, with rural diagnoses jumping during the summer months, while claim lines from November to April happened more often in urban areas.

“The top states in 2021, from highest to lowest, were New Jersey, Vermont, Maine, Rhode Island and Connecticut,” the study’s authors wrote. “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.”

Rounding out the top twenty, from highest to lowest, were Pennsylvania, New York, New Hampshire, North Carolina, Massachusetts, Virginia, Hawaii, Wisconsin, West Virginia, Delaware, Alaska, Washington D.C., Indiana, Maryland and Iowa.

FAIR Health President Robin Gelburd stated, “Lyme disease remains a growing public health concern. FAIR Health will continue to use its repository of claims data to provide actionable and relevant insights to healthcare stakeholders seeking to better understand the ongoing rise of Lyme disease cases.”

Most cases of Lyme disease can be treated successfully with a few weeks of antibiotics, according to the CDC. Insect repellent, prompt tick removal, using pesticides and reducing the tick habitat are all ways to decrease the chance of contracting the disease.