There is no hiding from Lyme disease-carrying deer ticks these days. But your best chance at avoiding them may be to head north on U.S. Route 1 and don’t stop until you reach the Canadian border in Fort Kent.
Since the state’s first reported sighting of a deer tick in 1996 on a red squirrel, they have spread to all of Maine’s 16 counties.
Despite this impressive population and range expansion, there are still places in Maine where you are less likely to encounter deer ticks, according to one of the state’s top tick experts.
“There is a population size gradient,” said Griffin Dill, manager of the University of Maine Cooperative Extension Tick Lab. “It’s one of those things where they have been able to march northward at a somewhat alarming rate for the last 25 years.”
Areas with the highest deer tick populations are southern Maine and along the coast, Dill said.
“The further north you go, the lower the population,” he said. “Once you are in Aroostook County, it’s quite low.”
The number of ticks in a given area seems to correspond to the habitat, Dill said.
“There is a bit of a habitat gradient,” he said. “In the southern part of the state and along the coast you have more of that mixed forest that is more conducive to deer ticks.”
The farther north you go, the forests go from mixed to dominated by conifers.
But it may only be a matter of time before deer ticks increase in the north.
“Climate change will play a role because now they are somewhat limited by the temperature range,” Dill said. “As temperatures warm, [deer tick] hosts like small mammals will be able to survive farther north and that can help the ticks in their northward march.”
Over a longer period of time, a habitat shift could also help facilitate the ticks’ northward expansion.
“That mixed forest, if it slowly starts getting a foothold in the north as temperatures change, could certainly create the habitat gradient facilitating the tick’s movement,” Dill said.
The deer tick, also known as the blacklegged tick, carries a bacteria that causes Lyme disease. People can get Lyme disease if bitten by an infected tick, and it can lead to heart problems, meningitis or arthritis if not treated. It is the most common tick-borne illness in the country.
In 2020 there were 1,118 reports of confirmed and probable cases of Lyme disease among Maine residents. That number was down 48 percent from the previous year.
At this point, according to Dill, Maine is now an endemic state when it comes to tick-borne diseases. In addition to Lyme disease, tick species in Maine carry anaplasmosis, babesiosis and the Powassan virus.
“Everywhere you go in Maine you should be vigilant,” Dill said. “If I am hiking in York or outside doing yard work I’d be more vigilant than if I were in Fort Kent, but that does not mean you should not be in the habit of checking yourself for ticks no matter where you are in the state.”
In fact, if you live in northern Maine now is the time to get into the habit of regular, full-body deer tick checks after going inside.
“Start now using repellents, even in far northern Maine, and checking yourself,” Dill said. “Even if the risk is lower, it’s better to get into those habits sooner rather than later.”