Rare Lyme disease strain Borrelia mayonii found in upstate New York

A rare case of Borrelia mayonii—a bacterium linked to Lyme disease—was confirmed in upstate New York last July. The infected individual, a resident of Herkimer County, had not travelled outside the area before falling ill. Health officials now warn that the region’s climate is creating ideal conditions for tick-borne illnesses to spread. The case emerged after ticks collected from the person’s wooded property tested positive for Borrelia mayonii. This strain, though uncommon in New York, has previously been found in the Midwest. A follow-up investigation examined over 1,500 ticks from 24 counties across the state, but no further traces of the bacterium were detected.

New York and the broader Northeast have seen Lyme disease cases surge in recent years. State records show a nearly 450% increase in reported infections between 2020 and 2024. Experts attribute the rise to warmer temperatures and shifting weather patterns, which allow ticks to thrive in areas once considered low-risk. To reduce exposure, health authorities advise using repellents containing at least 30% DEET or oil of lemon eucalyptus. These measures are particularly important for those living near or visiting wooded and grassy areas, where ticks are most active.

The discovery of Borrelia mayonii in Herkimer County highlights how tick-borne diseases are expanding into new regions. While no additional cases were found in the wider survey, officials continue to monitor the situation closely. Residents are urged to take precautions as Lyme disease remains a growing concern across the Northeast.