A rare strain of Lyme disease is emerging in the United States.
Recently, researchers and health officials from New York reported a case of Lyme disease caused by the bacterium Borrelia mayonii. This is the first instance detected in the state. Although the patient received antibiotics and recovered well, the finding raises concerns about the spread of this pathogen, which was previously confined to the Midwest.
“This study offers the first evidence of B. mayonii in New York ticks and a locally acquired infection,” the authors mentioned in their paper, published in the Morbidity and Mortality Weekly Report (MMWR) from the Centers for Disease Control and Prevention.
A different type of Lyme
Lyme disease is caused by several Borrelia bacteria, transmitted mainly through various tick species. The predominant type causing Lyme in the U.S. is B. burgdorferi. However, in 2016, researchers at the Mayo Clinic in Minnesota identified another species, B. mayonii, capable of causing Lyme disease.
Both Borrelia types are generally spread by the bite of the blacklegged or deer tick (Ixodes scapularis) and respond to the same antibiotics, yet they can lead to differing symptoms. Individuals infected with B. mayonii are more likely to see rashes all over their bodies rather than a single bullseye rash usually linked to B. burgdorferi. They may also experience additional symptoms like nausea and vomiting, not to mention higher levels of B. mayonii in their bloodstream, potentially leading to more severe illness.
This specific case was discovered last summer in a resident of Herkimer County, Central New York. The person began experiencing tickborne infection symptoms in late June, which led to testing. A commercial lab subsequently informed the New York State Department of Health about a positive result for B. mayonii in early July.
Until now, cases of B. mayonii were only reported in Minnesota and Wisconsin. The patient mentioned spending time outdoors but had no recent travel history, suggesting infection likely came from local ticks. Following this, health officials collected and tested ticks from the person’s yard and local hiking trails.
During one tick collection effort, they found one nymph that tested positive for B. mayonii, leading to another collection in October, where they discovered nine adult ticks, all from the same property. Interestingly, when testing tick samples from other New York counties dating back to 2021, researchers found no instances of B. mayonii, hinting that it might have only recently appeared in the area.
To make matters worse for the patient, they also tested positive for another tickborne illness at the same time, anaplasmosis. Fortunately, treatment with doxycycline resulted in a full recovery.
The future of B. mayonii
While B. mayonii could potentially lead to more severe illnesses on average, it has remained a relatively rare cause of Lyme disease since its discovery. Thus, it’s unlikely to surpass B. burgdorferi, which is the most frequently reported tickborne disease in the United States.
Nonetheless, its unexpected emergence in New York—far from Minnesota and Wisconsin—is concerning and somewhat baffling. The higher prevalence of the bacterium in adult ticks suggests an established animal reservoir in the area, possibly mice or squirrels, rather than a one-time introduction via migratory birds.
Regrettably, B. mayonii is just one of many tickborne diseases potentially becoming more frequent in the U.S. as tick populations grow with climate change. Therefore, monitoring the spread of these infections is crucial, according to the researchers.
“We need ongoing surveillance in entomology, molecular biology, and human tickborne diseases to understand how emerging tickborne pathogens are spreading and their public health impact in New York,” they stated.
