A New Cause of Lyme Disease Has Been Discovered

Lyme disease is an infection caused by a bacteria passed to humans from infected blacklegged ticks, and according to a new report from United States health authorities, there’s now a new culprit.

In a new study published in the journal Lancet Infectious Diseases researchers at U.S. Centers for Disease Control and Prevention (CDC) as well as experts in Minnesota, Wisconsin, and North Dakota report that a newly discovered species of bacteria called Borrelia mayonii causes Lyme disease. The new bacteria is related to a strain that has long been linked to the disease and was thought to be the only cause of lyme in the U.S. Researchers came across the new bacteria after lab tests from six people with suspected Lyme came back unusual. The bacteria was genetically distinct from the usual suspect.

Like the more well-known Borrelia burgdorferi, Borrelia mayonii causes symptoms like fever, rash, headache, and neck pain, and as the disease progresses it can cause arthritis. Unlike the original strain, though, Borrelia mayonii can also cause vomiting and nausea. The initial bacteria was also characterized by a rash that looked like a bull’s eye, but an infection with Borrelia mayonii can cause a more widespread rash on the body.

Currently, the study authors note that the new strain appears to be limited to the upper midwest United States. People with Lyme disease caused by Borrelia mayonii also responded well to the same antibiotics used to treat the usual bacteria.

“CDC is working closely with state health departments in Minnesota, North Dakota, and Wisconsin to better understand B. mayonii and to plan future investigations, including better descriptions about the clinical aspects of the illness and the geographic extent of the infected ticks,” the agency said in a statement.