Ticks bite him several times a week from May through November. Some days, he’s removed as many as 60 from each of his two working dogs. “It’s brutal out here,” he said. “You talk to other farmers, and they don’t talk about the weather anymore. They talk about how bad the ticks are that day.”

As the planet warms, tick populations, and the diseases they spread, are exploding. Nine species are linked to illness in the U.S. When ticks bite, they can transmit bacteria, viruses, and parasites that lead to debilitating illnesses like chronic Lyme disease or babesiosis. Some pass allergens that can trigger alpha-gal syndrome, a red meat allergy that is sometimes fatal. Such tick-borne diseases have more than doubled in the U.S. in the past 15 years.

In the East and Upper Midwest, farmland and suburbia with patches of forests—as well as humid weather—favor the spread of tick populations. That’s where the biggest boom of multiple species is happening, though the arachnids are on the march nearly everywhere in the U.S. A western deer tick is gaining ground in California and other Western states, spreading Lyme disease and anaplasmosis.

Farmers, who spend much of their time outdoors, are at an elevated risk for tick-borne illnesses, which can have devastating health and economic consequences. Personal protection measures and farm management changes offer some protection, but ultimately experts say that farmers need to step up efforts to control deer, a primary host for ticks, on their own land.

People too are spending more time outside during winter. “We have more interactions of humans and ticks for a prolonged period because of climate change,” said Gargi Deshpande, an infectious disease epidemiologist at the University of Oklahoma.

Warmer temperatures are also expanding the range of ticks into higher latitudes. “Even five to ten years ago, it really wasn’t much of a concern in Canada, or parts of New York, but now they’re seeing a lot more,” said Mandy Roome, associate director at Binghamton University Tick-Borne Disease Center.

But climate change isn’t the full story. Expanding deer populations are also part of the problem. Though ticks feed on rodents, small mammals, and lizards when early in their life as nymphs, many species rely on deer for the final blood meal that allows them to mate and lay eggs. A single deer tick lays 2,000 eggs after feasting on a deer, while a lone star tick lays 3,000.

Humans have inadvertently created prime deer habitat by abandoning farmland or allowing it to revert to woodlands, said Eli Arnow, forest health task-force lead at the nonprofit Understory, which focuses on ecosystem health in the Hudson Valley. “We’ve created the perfect fragmented habitat for deer, which is what they want. They’re not creatures of the deep dark woods. They’re at the edges.”

“We’ll hit a dry spell, and they’ll go a little bit quiet, but it’s not bookended by the seasons anymore. They’re active all summer. There’s both more nymph ticks, which are tiny and harder to see, and more giant ticks crawling on you.”

Warner’s farm is a mix of woodland and pasture with a lot of edge habitat. He plants native grasses and high-energy forage grasses such as timothy, rye, oats, and peas in his pastures.

“It’s all just tick habitat,” he said. “They’re going to get on me. The most important thing is to get them off as soon as possible. We are in our office bathroom tick checking every time we come out of the fields.”

“We’ve known farmers that have completely had to sell their farm because they were chronically ill and couldn’t keep up with the operation.”

Studies show it generally takes 24 to 48 hours for a deer tick to transmit a disease like Lyme or babesiosis. So, although Warner has been bitten many times, he’s never seen a bullseye rash, the telltale sign for transmission of Lyme disease, nor developed a tick-borne illness.

Lone star ticks, however, are thought to transmit the allergens linked to alpha-gal syndrome almost immediately, said Sam Telford, a professor at the Department of Infectious Disease and Global Health at Tufts University.

Fortunately, Warner has yet to encounter a lone star tick, though as a cattle farmer he is frightened by that prospect. “Getting allergic to my product would be pretty bad,” he said.

Lyme disease causes fever, aches, fatigue, and severe neurological, joint, and heart disorders if left untreated. It is the most common tick-borne illness, with an estimated 476,000 patients diagnosed each year. Farmers interviewed for this story mentioned other farmers so debilitated by Lyme they’ve had days they couldn’t get out of bed, or have suffered worse symptoms, like Lyme carditis or meningitis, and had to relearn how to walk and talk.

“We’ve known farmers that have completely had to sell their farm because they were chronically ill and couldn’t keep up with the operation,” Roome said.

Roome studied tick exposure on 46 Vermont farms over two years and concluded that farmers were at increased risk for tick-borne illness. Farmers reported as many as 70 tick encounters each during a six-month period, and 12 percent had been diagnosed with a tick-borne disease. Though no U.S.-wide study of farmers’ tick exposures has been conducted, the Center for Disease Control warns that all outdoor workers are at a higher risk.

Roome’s research points to fences as hot zones. Fence repair was the activity most associated with ticks, she said. “That’s when you’re at that edge habitat and that’s where ticks thrive.”

Valerie Maben, a 28-year-old farmhand at a vegetable farm in New York, has had Lyme disease three times, with lingering symptoms that include brain fog, anxiety, and confusion; syncope, or fainting episodes from sudden swings in her heart rate; and extreme fatigue.

Maben first got Lyme at 20 while working in an orchard. Like 75 percent of people who develop the disease, she never saw the tick nor a bullseye rash, so her treatment was delayed.

“The first time, I thought I had the flu and then it just was getting worse,” she said. Eventually she got a Lyme test and took a course of antibiotics. “It took me a while to get back into mentally feeling well, remembering stuff, and being able to function,” she said.

Her subsequent bites happened while she was working landscape jobs. The second time she started feeling faint and had to wear a heart monitor because of fluctuations in her heart rate. Again, she never saw the tick.

Getting diagnosed with Lyme the third time was frustrating, she said, “especially when I’m in the throes of the season, and it takes me out for a while.” Maben doesn’t get paid when she doesn’t work. “I go back and forth on whether I should be taking care of my health or exhausting myself.”

Though she’s better now, Maben still experiences occasional bouts of fatigue and joint pain—and more extreme fatigue when she gets a cold or other illness.

The lone star tick, which is fast advancing from the south into the Northeast and Midwest, causes alpha-gal syndrome. The allergy develops when the immune system begins producing an antibody against alpha-gal, a sugar found in most mammals but not humans. Scientists don’t fully know why the reaction arises after a tick bite.

“It’s a big mystery still because it’s a relatively new disease, and we don’t understand what the tick is doing to give us alpha-gal,” Telford said.

For some people who have been bitten, even the smell of meat cooking or contact with livestock fluids can elicit symptoms such as hives, difficulty breathing, or abdominal pain. Some even go into anaphylaxis shock and die. Others never develop the allergy.  The symptoms often abate over time with abstention from meat and dairy.

Kristen Kinser, who has farmed vegetables for 30 years on Martha’s Vineyard, has had Lyme 13 times and alpha-gal syndrome five times.

Kinser first contracted alpha-gal before the Covid pandemic, when no one really knew what it was, she said. An alternative practitioner deduced she’d developed an allergy to some unknown substance and put her on a homeopathic remedy.

“It actually went away,” she said, “and then I got bitten again.” Now Kinser refrains from eating beef or lamb, but says she can still get itchy or feel nerve pain. “Sometimes I feel almost tooth pain in my shoulder.”