The Centers for Disease Control and Prevention (CDC) announced the discovery of a new species of Borrelia mayonii that causes Lyme disease. Prior to this report, Borrelia burgdorferi was the only species of bacteria believed to cause Lyme disease in North America. 

The findings, published in Lancet Infectious Diseases, showed unusual lab test results from 6 out of 9,000 people infected with suspected Lyme disease between 2012-2014. Analysis of the bacteria’s DNA sequences revealed a previously unrecognized Borrelia species. Researchers at the Mayo Clinic in Rochester, MN, reported that additional genetic testing showed that the new bacteria B. mayonii was closely related to B. burgdorferi.

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B. mayonii causes fever, headache, rash, and neck pain in the early stages of infection, and arthritis in later stages of infection like the illness caused by B. burgdorferi. However, B. mayonii also causes nausea, vomiting, diffuse rashes (instead of the single “bull’s-eye” rash), and a higher concentration of bacteria in the blood. 

The newly discovered bacteria is thought to be transmitted to humans by the bite of an infected blacklegged “deer” tick. B. mayonii has been detected in blacklegged ticks in at least 2 counties in northwestern Wisconsin with likely patient exposure sites in north central Minnesota and western Wisconsin. Currently available evidence suggests that B. mayonii is limited to the upper midwestern U.S; it was not identified in any of the >25,000 samples from residents of 43 other states with suspected tickborne diseases taken during the same study period. The CDC informed that specific identification of B. mayonii can be done by using polymerase chain reaction (PCR) assays. The bacteria may also be seen on a blood smear in some cases. 

The infected patients included in the report were successfully treated with common antibiotics for Lyme disease caused by B. burgdorferi. Healthcare providers are recommended to follow the regimen described by the Infectious Diseases Society of America when treating patients infected with B. mayonii

In general, the CDC recommends the following to reduce the risk of tick bites and tickborne diseases:

  • Avoid wooded and brushy areas with high grass and leaf litter;
  • Use insect repellent when outdoors;
  • Use products that contain permethrin on clothing;
  • Bathe or shower as soon as possible after coming indoors to wash off and more easily find ticks;
  • Conduct a full-body tick check after spending time outdoors; and
  • Examine gear and pets, as ticks can come into the home on these and later attach to people.

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