The number of ticks that carry Lyme disease has climbed in recent years. A recent study by Dartmouth researchers and several other universities found that 50% of adult blacklegged ticks in northeastern United States carry the bacteria that causes Lyme disease.
The study summarized and analyzed existing research on tick abundance and pathogen prevalence across five states — Connecticut, Maine, New Hampshire, New York and Vermont — from 1989 to 2021, according to postdoctoral fellow Lucas Price.
“We had collaborators from five different states … trying to figure out how to manage [blacklegged ticks] on the landscape and how to manage risk to people, and that work is going to continue, including work going on at Dartmouth College,” Price said.
However, Price added that tick abundance in the southern part of the study has become “fairly stable,” while there are still some increases in northern regions.
Biology professor Matthew Ayres, who studies how climate change affects the distribution of insects and was not involved in the study, said that the life cycle of blacklegged ticks is “marvelously complex” because they take blood meals — feeding on a host animal’s blood — at each life stage.
If a tick gets a blood meal from an animal that is carrying Lyme disease, it will then contract the bacteria and pass it on to animals or humans that it bites, Ayres said.
Ticks are more prevalent in fall and spring as they search for blood meals, Ayres added.
“There’s two times during the year when most tick-human encounters happen, and one of them is the time beginning just now — spring,” Ayres said.
Ayres also stated that there has been an increase in tick distribution in the northeastern United States that is responsible for higher rates of Lyme disease in the region. The temperature of the coldest night of the winter has gotten warmer. Since ticks have a “particular lower lethal temperature,” warmer winters mean that more ticks are going to survive.
“We can say with high confidence that it's because the coldest night of the winter has been getting warmer, and it's gotten warmer over the last 60 years by more than four degrees celsius,” Ayres said.
Anabel Agre ’28, who is from Durango, Colorado, where ticks are not very common, said that she didn’t have to seriously worry about ticks before coming to Dartmouth. While she does tick checks after longer backpacking trips back home, concerns about Lyme disease are “not as big of a deal” as they are in New Hampshire.
“Usually when I’m out in the wilderness, we don’t worry quite as much around ticks,” Agre said.
However, she has been taking “more precautions” since coming to Dartmouth, including wearing longer clothing and doing more tick checks after going on hikes.
Kalen Hixson ’28, who is from Camden, Maine, said he was unaware of the percentage of ticks that carry Lyme disease despite coming from a place where ticks are “very common.” However, Hixson said his family always does tick checks on each other and their dogs after being in the woods or tall grass.
“My family has dogs, and it's really common to find ticks on dogs as well,” Hixson. “So we try to remember.“
First Year Trips are a common setting where students from areas with lower rates of Lyme disease are introduced to tick checks. Katherine Gazzini ’25, who has served as a trip leader in the past, said trip leaders receive information about bug spray, tick checks and Lyme disease symptoms to monitor for.
Gazzini, who has experienced severe Lyme disease in the past, said she emphasizes the importance of taking ticks seriously when informing students about safety precautions during First Year Trips.
“It seems like such a non-issue just because it's these small little bugs, but … they should be taken as seriously as mosquitoes carrying viruses,” Gazzini said.
Chief health and wellness officer Estevan Garcia said students can “reduce exposure” to ticks by avoiding grassy areas and treating clothing with insecticide.
Garcia also said it is important for students to do tick checks on themselves at the end of the day, in addition to checking their gear. During tick checks, students should pay special attention to hidden areas, such as their underarms, bellybuttons, behind the ears, waist, between the legs and behind the knees. He also advised students to shower soon after getting back from the outdoors.
Act fast, Garcia continued.
“The quicker you can get the ticks off you, the better off you are,” Garcia said.
Garcia added that an early sign of Lyme disease is a rash that forms a “ring around where the tick would be.”
Students who think they have been exposed to ticks and Lyme disease can get evaluated at Dick’s House, where they can get a referral to get testing at Dartmouth-Hitchcock Medical Center.
