Once called Nantucket fever, this nasty tick-borne illness is on the rise

Micheline LeBlanc knew something was up in the summer of 2022. She felt achy and fatigued. “Headaches were a big problem. Night sweats were dramatic,” LeBlanc says.

When she developed throbbing pain in her legs and shortness of breath, her husband took her to the hospital, where she was diagnosed with Lyme disease.

They sent her home with antibiotics. But a few days later her doctor called to tell her a blood test showed she actually had a different tick-borne illness – babesiosis.

The first case of babesiosis in the U.S. was identified on Nantucket Island in 1969. The tick-borne parasitic disease is endemic in New England, and as deer ticks expand their range it’s now found from Virginia to Maine as well as the upper Midwest, from Michigan to Minnesota. The CDC points to a significant increase in incidence over the last decade.

Babesiosis can be treated with drugs, typically a seven to 10 days course of an antibiotic, azithromycin combined with atovaquone, which are both prescription medications. But, sometimes, this isn’t enough to kill off the parasite, and there’s a risk of relapse.

Now, researchers are launching a randomized, controlled clinical trial, slated to begin this month, to test whether the anti-malaria drug — tafenoquine — in combination with the other drugs already used, can speed up recovery and clear the parasite from patients’ bodies faster.

Most younger people who get infected after a tick bite have only mild illness. “A fever that can take a couple of days to a week or two to go away,” says Linden Hu, an infectious disease doctor at Tufts University. Some people have no symptoms. But some people over 50 as well as those with compromised immune systems can become very ill and end up in the hospital.

That’s what happened to LeBlanc, “It was a roller coaster ride,” she says.

LeBlanc lives in New Hampshire, where ticks are common. She would feel better for a few weeks, but then her symptoms would return. She had headaches and fatigue. LeBlanc had her spleen removed in her 20s after an infection and her immune system was compromised from a prior illness which put her at high risk.

“These patients can have many relapses, lasting months or sometimes even years,” explains Dr. Peter Krause, an infectious disease physician and babesiosis expert at the Yale School of Public health. And a small percentage die.

A small case study published last month provides some initial evidence that tafenoquine is beneficial for these patients. The study included five people including LeBlanc, 72.

When doctors added tafenoquine to these patients' regimen, they got better.

“It worked,” Dr. Krause says. “They no longer had symptoms and they no longer had the organism in their blood.”

When LeBlanc went to the hospital for testing after taking the drug, the doctors began to document a significant decline in the parasite within a few weeks. “It went down and down, and then it was not even found in my system,” she says. And she started to feel much better, “I was elated,” LeBlanc says.

Now she's back doing all the things she couldn’t do while she was sick, such as dancing and volunteering. “It’s just great,” LeBlanc says.

Researchers plan to enroll hospitalized patients this summer who are admitted with babesiosis, explains Edouard Vannier of Tufts Medical Center, one of the trial sites. “Now the tick season has started we are going to see patients coming to the hospital,” Vannier says.

He says they will not include patients with mild disease because the existing drug regimen of azithromycin combined with atovaquone already does a good job. He says enrollment should be “up and running very shortly.”

Currently tafenoquine is approved by the FDA for malaria treatment and prevention. For now, doctors are using the drug ‘off-label’ in babesiosis patients, but the ongoing research could pave the way for FDA expanded approval of the drug for the tick-borne disease. “That’s our goal,” says Dr. Geoff Dow, CEO of 60 Degrees Pharma.

Given the rise of babesiosis, there’s also more testing for the disease. It can be diagnosed with a blood test. The FDA recommends blood donation screening for the parasite that causes babesiosis in 15 states.

LeBlanc says she’s now very careful now to avoid tick bites. The CDC advises people to protect themselvesby walking on trails, using repellent, wearing long-sleeve pants and shirts when outdoors, especially in wooded areas and showering soon after being outdoors. And be especially careful in spring, summer and fall when ticks are most active.

Find Allison Aubrey on Instagram at @allison.aubrey and on X @AubreyNPR.

This story was edited by Jane Greenhalgh