A new strain of Lyme disease has emerged in New York State, raising public health concerns.

Most tick-borne diseases in the United States are caused by Borrelia burgdorferi, a corkscrew-shaped bacterium. However, there is another rarer species called Borrelia mayonii, which has thus far only been found in Minnesota and Wisconsin, both spread via deer ticks.

Recent CDC reports indicate that cases of B. mayonii Lyme disease were identified in upstate New York as of last July.

This infection was diagnosed in an adult from Herkimer County, extending from Utica to the Adirondack Mountains, who had not traveled recently.

The state health department found several infected ticks on the person’s property; however, a broader study of over 1,500 ticks across 24 New York counties yielded no bacteria.

The exact origin of the bacteria in Herkimer County remains unclear.

“Although this discovery was unexpected, tick species and tick-borne diseases can fluctuate geographically,” stated a spokesperson from the New York State Department of Health.

Douglas Norris, a molecular microbiology and immunology professor at Johns Hopkins Bloomberg School of Public Health, suspects that the bacterium has been present in New York ticks for several years but remains tightly contained.

Different Symptoms, Same Disease

Research on B. mayonii is limited compared to B. burgdorferi, having been discovered only in 2016 by Mayo Clinic researchers. Both species can lead to severe illness.

Symptoms can start with fever and headache. However, Lyme disease caused by B. mayonii is more likely to result in nausea and vomiting.

Norris noted that individuals infected with this less common species may not develop the rash typically seen around the tick bite. Instead, they may exhibit a rash of small red spots over a broader area.

Dr. Bobby Pruitt of the Mayo Clinic emphasized the potential for a range of neurological symptoms. “Many broader symptoms might still be unrecognized,” he noted.

The health department did not specify the symptoms exhibited by New Yorkers infected with B. mayonii last year.

Rising Lyme Disease Cases

Cases of Lyme disease have been rapidly increasing in New York. From 2020 to 2024, the incidence rose nearly 450%, soaring from about 37 cases per 100,000 people to 165 cases per 100,000. According to Department of Health statistics.

Potential occurrences of B. mayonii may rise across the Northeast, but infections remain rare, according to Pruitt.

Norris adds, “Borrelia burgdorferi will likely remain the predominant cause of Lyme disease in the U.S. and B. mayonii is not primarily responsible for it.”

Even in areas where B. mayonii has been previously documented, like the upper Midwest, cases are few. For instance, out of Minnesota’s roughly 3,000 annual Lyme disease cases, only about 2 are attributed to B. mayonii, according to the Minnesota Department of Health.

A study revealed that only 0.2% of larval ticks in New York carried B. mayonii, while around 1% of adult ticks did. In contrast, approximately 25% of nymphs and 50% of adult ticks are infected with B. burgdorferi in the Northeast.

Timing is crucial, as it takes 24 to 48 hours for ticks to transmit infectious bacteria after attachment. Therefore, the smaller nymphs are typically the responsible vectors for Lyme disease.

“People often see larger ticks, but these smaller ones typically go unnoticed,” Norris explained.

Impact of Climate Change on Lyme Disease

Norris stated that while tick-borne diseases are evolving due to climate change, this is likely not the reason for the emergence of B. mayonii in New York.

“Unfortunately, it was introduced right where it could thrive,” he noted.

Experts speculate that the bacteria may have been transported by infected ticks on migratory birds from Minnesota or Wisconsin.

New York has a climate conducive to tick reproduction and the survival of Lyme disease pathogens, creating a “sweet spot” that is shifting northward due to climate change, resulting in increased Lyme disease cases in areas previously known for their endemic status.

To minimize the risk of tick bites, experts recommend staying in the center of trails during hikes and avoiding tall grass. Wearing long sleeves and tucking pants into socks can provide additional protection. Using a repellent with 30% DEET or lemon eucalyptus oil is also advised. Regular tick checks after outdoor activities are essential, as is showering to remove ticks after being in tick-prone areas.

“We aim to encourage outdoor activities while ensuring people take necessary precautions against tick bites,” experts say. “Ticks can transmit various pathogens and diseases, so awareness is crucial.”