When University of Vermont entomologist Cheryl Frank Sullivan surveyed 585 northern New England crop farmers two years ago, 90 percent reported they'd spotted ticks crawling on their bodies or clothing. Her results confirmed a commonsense assumption: Farmers, whose livelihood requires time in fields and woods, are particularly susceptible to tick bites, and thus to Lyme disease and other debilitating illnesses that ticks spread.
Sullivan is following up this year with a second survey that focuses on agricultural workers in Vermont. At the same time, a scientist in New York State is studying Vermont farmers as she looks for ways to reduce the risk of tick-borne illness on farms.
In recent years, the bloodsucking arachnids have become such a hazard that farmers are changing their behaviors. Many are avoiding areas of dense brush, treating their clothing with tick repellent and trying other tactics.
Five of Vermont's 14 tick species carry pathogens, although the tiny black-legged tick, also known as the deer tick, is responsible for more than 99 percent of all tick-borne disease reports, according to the Vermont Agency of Agriculture, Food and Markets. Those diseases include Lyme, anaplasmosis and babesiosis, which can cause severe and lasting illness.
"The possibility of getting Lyme disease is one of the biggest fears I have in working in the woods," said Mike Farrell, cofounder and general manager of the Forest Farmers, a company that taps thousands of acres of maple and birch trees in Marshfield and the Adirondacks. Farrell, who has worked in the maple industry for 20 years, said the company issues work pants treated with the insecticide permethrin to its crew members, some of whom travel from Jamaica to help out at busy times. Forest Farmers counsels its workers to check for ticks at the end of the day.
"It's just constant vigilance and checking," Farrell said. "Especially if you've been in an area that you know is brushy."
In recent years, the Green Mountain State has become a host for potentially groundbreaking tick research that examines the impact of ticks on agricultural workers, and some potential solutions.
In 2022, Amanda Roome, a researcher at the Northeast Center for Occupational Health and Safety in Cooperstown, N.Y., chose Vermont for her tick study because at that time the Green Mountain State had the nation's highest incidence of Lyme and anaplasmosis. (Rhode Island now has the highest incidence of Lyme.)
Roome's group, which looks for ways to keep workers safer, has targeted southern Vermont farms to test a simple tick control tool.
Her team places tubes containing cotton treated with permethrin near buildings where mice, common carriers of ticks, are found. The rodents take the cotton to use as bedding, and the poison kills the ticks they carry. Some homeowners in Vermont and elsewhere already use the tubes, which are safe for children and pets and can be purchased in hardware stores.
Roome has placed tubes on 46 farms involved in the study. Tubes at only half the farms, chosen at random, contain the pesticide. Ultimately, the study will ask farmers to assess whether tick numbers declined, and after two years, researchers will compare data from the two groups of farms.
Roome and her staff also plan to hold what they call "tick talks" with dairy and livestock workers to learn what prevention measures, if any, they are using now.
"Given the rate of Lyme and other tick-borne illnesses in Vermont, we thought it was the perfect opportunity," Roome said last month. "If this is promising, we would love to expand the research."
Roome is hoping to find a tick-bite prevention strategy that will help on farms like Chester Abbot's 60-cow operation in Randolph. Abbot, 55, has been living with Lyme disease for 20 years. He tried antibiotics without success, then pursued a host of conventional and alternative treatments for the fatigue and flu-like symptoms. He's become extra vigilant as he farms, checking for ticks and urging his three sons to do the same. But he sees ticks moving around on his cows, and he noted that he leans his head on their flanks when he's milking.
"Sometimes I come in from milking, and I've got ticks running all over me," Abbot said. "It's stressful."
At UVM, entomologist and assistant professor Sullivan also studies the impact of ticks and tick-borne illness on farmers. Sullivan focuses on pest-reduction strategies in landscapes, with chemical pesticide considered a last resort. Her 2022 survey asked farmers who grow crops in Maine, New Hampshire and Vermont about their experience with ticks. More than 85 percent said they considered ticks to be an occupational hazard, and nearly all had had to remove ticks from their clothing or bodies.
Most reported that they performed daily tick checks, wore long pants and shirts, treated their clothing with insecticide, and put work clothes in the dryer to kill ticks. Some said they laced flea collars through their boots and shoes.
Last summer, Sullivan created another survey, this one aimed at learning more about tick management, specifically in Vermont agriculture. She said small farms present prime feeding ground, with agricultural spaces nestled next to the forested habitat that tends to harbor ticks.
She is seeking to learn how much information agriculture workers have about ticks and disease risk, asking them to identify the black-legged tick from a lineup of three drawings. She draws out respondents' experiences in spotting ticks and removing embedded ones from themselves, pets and livestock.
Sullivan leads many tick-related projects, and her goal with the survey, which she plans to keep open for two more months, is to hone future research aimed at helping farmers. She wants more farmers to understand there are steps they can take to reduce their risk, such as mowing field perimeters and removing wildlife that hosts ticks. She thinks farmers have received less attention than others who work outdoors.
"There really isn't a lot of information specific to farmers about encountering ticks and having animals encounter ticks," she said. "We need to help them better understand that."
It's not clear why Vermont's illness rates are among the highest in the nation, and scientists don't fully agree on how much tick populations have changed, or why, in recent years. The Northeast Center for Occupational Health and Safety reports that 75 percent of the people diagnosed with Lyme disease do not recall being bitten. Diagnosis can be uncertain because it can take several weeks after the bite for an infection to be detectable by a blood test.
Tick removal has become part of the animal care routine at Dorset Equine Rescue, said barn manager Tiffany Vittum, who cares for about 20 horses. Populations rise and fall from year to year.
"Some years, I'll go riding in the woods and come back, and the horse's legs will just be crawling with ticks," she said, adding that she's been bitten by ticks every year but hasn't contracted a tick-borne illness. "I have to pick them off one by one."
At Fern Bridge Farm in Ferrisburgh, owner Kelly Otty credits the tick-eating possums that raise their litters in her garden, as well as the farm's 50-chicken poultry flock, with keeping down tick numbers. Otty, who raises 60 Shetland sheep, has found ticks embedded in her skin but has dodged tick-borne illness so far.
Many farmers in Vermont swear that their chickens have helped them reduce their tick populations, although scientists say there's no evidence they do.
"We found that there's virtually no science to back up these claims," says TickEncounter, a well-regarded website of the University of Rhode Island. TickEncounter notes that ticks often attach themselves to chickens.
Otty, though, is convinced.
"We brought in chickens early on. They're rotated through different areas, and we allow them to hang out on the lawn," said Otty, who moved to the property 14 years ago. "We noticed a pretty remarkable decrease in ticks after that."