Rare type of Lyme disease found for the first time in New York - NBC News

There’s a new type of Lyme disease in New York state.

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Almost all cases of the tick-borne illness in the United States are caused by corkscrew-shaped bacteria called Borrelia burgdorferi. But B. burgdorferi is actually one of two Lyme disease-causing species in the U.S. The other, Borrelia mayonii, is far rarer. Until now, it has ever been detected only in Minnesota and Wisconsin. Both types are spread by deer ticks.

According to a Centers for Disease Control and Prevention report published Thursday, a case of B. mayonii Lyme disease was detected in upstate New York last July.

The novel infection occurred in an adult living in Herkimer County, which stretches from the edge of Utica into the Adirondack Mountains. The person hadn’t recently traveled, according to the report.

The State Health Department found a handful of ticks on the person’s wooded property that tested positive for the bacterium. But a much wider search, of more than 1,500 ticks from 24 New York counties, didn’t find it again.

It’s unclear exactly how the bacterium made its way to Herkimer County.

“While this finding was unexpected, we do know that a range of ticks and tick-borne disease can change geographically over time,” a spokesperson from the New York State Health Department said in an email.

Douglas Norris, a professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health in Baltimore, said the bacterium has most likely been present in New York ticks for a couple of years, though it appears to be contained to a very small area.

Same disease, different symptoms

Researchers know much less about B. mayonii than they do about B. burgdorferi. There have been far fewer infections from the former to study, and the bacterium was discovered by Rochester, Minnesota-based Mayo Clinic researchers only in 2016 — 35 years after B. burgdorferi. Both species can cause debilitating disease.

Both infections can begin with a fever and headache, but Lyme disease caused by B. mayonii is likelier to cause nausea and vomiting.

People infected with the less common species may also forgo the disease’s hallmark bullseye rash that surrounds the tick bite, Norris said. Instead, they may have a more widespread rash, which could look like tiny red spots over a part of their body, rather than just over the bite.

“People also have more neurological symptoms,” said Dr. Bobbi Pritt, a pathologist at the Mayo Clinic. Pritt was one of the scientists who discovered the B. mayonii bacterium. “There could be more broad symptoms that we haven’t seen yet.”

The health department would not disclose what symptoms the New Yorker infected with B. mayonii last year had.

Rising cases of Lyme disease

Lyme disease cases have skyrocketed across the Northeast in recent years. From 2020 to 2024, the incidence of Lyme disease in New York state increased by nearly 450%, from about 37 cases per 100,000 people in 2020 to nearly 165 cases per 100,000 in 2024, Health Department statistics show.

Although more B. mayonii cases are likely to show up throughout the Northeast, these infections are expected to remain rare, Pritt said.

“I think Borrelia burgdorferi will remain the most common form of Lyme in the U.S. We know Borrelia mayonii is not the primary cause of Lyme disease to start with,” she said.

Even in the Upper Midwest, where B. mayonii have been detected in the past, the bacterium causes a minority of Lyme disease cases. B. mayonii causes only about 2 of the nearly 3,000 cases of Lyme disease cases detected in Minnesota every year, according to the Minnesota Health Department.

Just 0.2% of nymphs, or young ticks, collected throughout New York carried B. mayonii, compared with about 1% of adult ticks, the Health Department found. On the other hand, B. burgdorferi infects about one-quarter of nymphs in the Northeast and half of all adult ticks.

Ticks have to be attached to a person for 24 to 48 hours before they can pass on infectious bacteria, so stealth is key. For this reason, nymphs, which are about the size of a poppy seed, are typically the ticks that spread Lyme disease, Norris said.

“A big tick a human will usually notice, but those little guys not so much,” Norris said.

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