Warmer Maine Winters And Rising Humidity Mean More Ticks — And Tick-borne Diseases

Sep 19, 2019

This week Maine Public is focusing coverage on climate change, and threats it poses to Maine and to the planet. Among those threats is an increasing number of tick-borne diseases. Researchers say warmer winters and rising humidity have helped fuel the northward expansion of the ticks' range. Changes in climate are also making Maine more hospitable for new species of ticks and the diseases they carry.

As many people do during the summer in Maine, Julia Maher and her family flocked to Sebago Lake this past July for a day on the water. They walked about a mile on a trail through woods and grass to get to the beach.

"And when we got to the lake I realized that I had a tick,” she says, “a deer tick on my arm, kind of the inside of my elbow."

She removed the tick and didn't think much of it. But three weeks later, Maher started to feel sick.

"So I had a fever and just didn't feel myself, didn't have a lot of energy. A lot of intense body aches, joint aches, headaches, and very intensive night sweats," she says.

Maher figured she was hit with a bad case of the flu. After a few days, she felt better, but within a week, the symptoms returned.

"The flu does not return within a week. And so I figured it was probably something tick-borne."

She was right, and Maher's doctor diagnosed her with anaplasmosis. She was prescribed antibiotics and now, weeks later, she is feeling better. But she says she's still not at 100 percent.

Dr Susan Elias from the MMCRI lab, holding a poster about how the health of people is connected to the health of the environment and animals
Credit Patty Wight / Maine Public

Maher is among the growing number of Mainers who are contracting anaplasmosis. It's the second most common tick-borne disease in the state behind Lyme, says Maine Center for Disease Control epidemiologist Sara Robinson.

"It tends to follow the same patterns that Lyme does,” says Robinson. “Right now, the midcoast area is hardest hit. But we are seeing a northward and westward expansion of anaplasmosis as well."

In recent years, Maine has seen as many as 660 cases of anaplasmosis, up from just single cases in the early 2000s. Lyme disease has also been on an upward trend, growing from a few hundred cases more than a decade ago to a recent high of more than 1800.

These diseases have become more common as deer ticks have spread across the state, since they were first documented in the mid-1980s, says Chuck Lubelczyk. He's a vector ecologist at the Maine Medical Center Research Institute's Vector-Borne Disease Lab.

"Now the expansion of those ticks have gone from York County to covering the lower third of the state, where they’re now established and endemic, to outlying populations in Aroostook County near Houlton, and also in Downeast Maine near Grand Lake Stream, and Calais and Eastport," he says.

The spread of the deer tick in Maine has been made possible by several factors, says Lubelczyk. One is the abundance of deer, the key host for the tick's reproductive stage when females produce up to 3,000 eggs at a time. Maine is also heavily forested, which is prime habitat for ticks. And, changes in climate also favor ticks, says Dr. Susan Elias of the Vector-Borne Disease Lab.

"If you think about the northern tier of the state, it's still colder than the southern tier of the state,” Elias says. “But it has been warming relatively faster. And so that's going to be helpful to ticks."

Earlier ice outs and snow melts favor ticks in the wintertime, says Elias. And higher humidity favors them in the summertime.

Chuck Lubelczyk says these changes in climate also roll out the welcome mat for other species.

"One, which we don't think has reached Maine yet but is potentially on its way, is called the lone star tick." Lone star ticks have been found in Maine, dropped by migratory birds from the south. Historically, they haven't been able to survive the winter, says Lubelczyk. But that's changing.

"This tick is slowly moving its way up the eastern seaboard,” Lubelcuzyk says. “It's now established in Cape Cod, and in southeastern Massachusetts, where it wasn't there a decade ago, and it does seem to be moving up the coast. This tick, if it does arrive and get established in Maine, is going to be a game changer because it is highly aggressive."

Whereas deer ticks are passive pursuers of their blood meal, latching onto whatever delicious-looking creature walks by, Lubelczyk says the lone star tick actually pursues its host.

"I have heard anecdotally from people that have it established in their areas that you can hear the woods rustling with these ticks, they're so abundant," he says.

And they can transmit several diseases. They can even cause a severe allergy to red meat. The lone star is just one of several new ticks and pathogens that researchers are watching out for, says Susan Elias.

"There's just there's just a race on to keep up with the various species of ticks, as their ranges expand and as they move around the globe, and to keep up with the pathogens that they carry," says Elias.

With no indication that these vector-borne diseases will abate, Sara Robinson of the Maine CDC says they pose a challenge to public health.

"They're tricky because there's not a single cure, a single prevention message that's going to prevent people from getting sick,” Robinson says. "So that's our messaging, is that people need to take precautions and they need to protect themselves."

Which means following all the precautions: wearing repellant and protective clothing, doing daily tick checks and, Lubelczyk says, making your property inhospitable to ticks, because most tick-borne diseases are acquired around the home.

"We're not talking about you conquering ticks across the continent. Just take care of it on your property. Which is kind of manageable."

Clean up dead leaves, he says. Remove invasive plant species such as Japanese barberry. When reforesting, plant spruce, a traditional habitat in Maine that isn't conducive to ticks. And remember that ticks are active well into the fall.

This story is part of a week-long reporting project Covering Climate Now by Maine Public and more than 300 other news outlets around the world. The series comes in advance of the United Nations Climate Action Summit on Monday Sept. 23 in New York. More information here.