York County is the historical epicenter in Maine for vector-borne diseases. Since deer ticks first appeared in southern portions of the state in the late 1980s, they've gained a strong foothold — as have the diseases they carry, such as Lyme, anaplasmosis, and babesiosis. York County is also home to the state's only human cases of the mosquito-borne disease Eastern equine encephalitis.
But as the climate changes, Maine is becoming more hospitable to these vectors and diseases — and could see even more.
This story is part of our series "Climate Driven: A deep dive into Maine's response, one county at a time."
One of the best places to monitor for ticks and mosquito-borne diseases is at deer tagging stations, like the one at Meserve's Market in Wells. On a recent morning, hunter Bob Perry pulls in with a deer he bagged just hours ago in the back of his truck.
"Oh yeah. Look. There’s a tick right there on his face, there’s a tick back there, and there were some small black ones crawling around. I don't know if that’s one there, but they were crawling all over him," says fellow hunter Darren Roberts.
The sight of a carcass crawling with ticks might make most people recoil, but vector ecologist Chuck Lubelczyk from the Maine Medical Center Research Institute dives in. He uses tweezers to pluck out the ticks — which can swell to the size of a blueberry — and drops them into a vial. As Bob Perry watches, he laments how bad the deer tick problem has become.
"They're terrible. It's taken the fun right out of, you know, goin' out at any time, willy nilly, decide to go for a walk in the woods. You think about the ticks, you know?" Perry says.
Darren Roberts says he stopped turkey hunting because of ticks.
"You just sit there in the woods and they just fester on you. So deer huntin', I walk around, I move around. I don’t like just sitting. It’s definitely changed things for me. I’m not afraid of bugs and stuff, but I just can’t stand ticks," Roberts says.
Within minutes, Lubelczyk pulls off about a dozen of them off the deer
"This is still probably the hottest part of the state for finding ticks," he says.
During deer hunting season, researchers and partners with the institute fan out to tagging stations from York to Aroostook County to keep tabs on ticks. Getting these data in a big state like Maine can be a challenge, Lubelczyk says.
"But by working with hunters, this gives us a very good geographic snapshot in a very short period of time, where we can cover a lot of ground in the state," he says.
Lubelczyk says York County is a bellwether for northern counties. Deer ticks are expanding their range, and that's fueled, in part, by mild winters brought on by climate change. And in southern Maine, warmer winters make York County a potential home for new populations of ticks.
"So I think it's only a matter of time before we see another tick, like the lone star tick, appearing," he says.
The lone star tick, named because of its markings, has already worked its way up the eastern seaboard from Virginia to Massachusetts, bringing with it more diseases, like tularemia, which causes skin ulcers. The bite of a lone start can also trigger an allergy to red meat in some. The hope is that field surveys and surveillance at deer tagging stations will find the lone star tick before a population becomes established, and steps can be taken to eradicate them.
But Lubelczyk says when he thinks about climate change, he's even more concerned about mosquitoes, which can transmit West Nile and Eastern equine encephalitis, or EEE.
"It is one of those things that worries me. Because EEE, although rarer than things like Lyme diseases, is much more severe, for both people and animals," he says.
About 30% of people who get EEE die. And half of survivors have long term neurological symptoms. So at the deer tagging station, not only is Lubelczyk counting ticks, he's taking blood samples, as he explains to a hunter.
"So you guys are doing a study?" the hunter asks.
Lubelczyk responds, "Yeah. So what we're doing with the blood, we collect the blood, take a look for mosquito-borne diseases, and generally what we find is that deer act as a pretty good sentinel because a lot of livestock nowadays are vaccinated."
And what they also find is that EEE, once confined to York County, is now present statewide. It's unclear why that hasn't translated into human cases. So far, there have only been two reported in the state. But the U.S. saw an outbreak of 34 cases in 2019, and more than half were in New England. As climate change causes warmer, wetter weather, EEE could become a public health issue,
"Mosquitoes need water, and they need heat to really flourish," says Dr. Susan Elias, with the Maine Medical Center Research Institute.
In an especially wet spring or summer, York County could serve as the canary in the coal mine, warning that EEE is ramping up in Maine. That's why both monitoring and management are important.
"We have a lot of tools in the toolbox. And the hardest part is getting people to use these tools," Elias says.
That means getting homeowners to remove any standing water, where mosquitoes breed. Towns might need to do careful, controlled spraying. For ticks, management includes removal of invasive plants that help them flourish, such as Japanese barberry and bittersweet. It also means controlling deer populations because that's where ticks feed so they can lay eggs.
Back at the deer tagging station at Meserve's Market in Wells, Johnny Fleming remarks on one deer in the back of a truck: "This one’s bad. His whole underside is covered."
Lubelczyk climbs into the truck bed to pluck ticks from the deer brought in by Fleming and Dave Lavalle. Fleming says just the other day, he picked 17 ticks off himself while hunting. Lavalle says it's a stark contrast to their recent experience hunting for moose in northern Maine.
"We had nothing on us, not one tick. And we was in the woods for a week," he says.
That contrast between northern and southern Maine is diminishing, says Lubelczyk.
Stemming the tide on vector-borne diseases is difficult he says, but it can be done if enough people recognize the importance of controlling the spread of ticks and mosquitoes, and take precautions against them
