New bacterial species that causes Lyme disease discovered

Researchers in the US have discovered a new bacterial species that causes the infectious Lyme disease in people.

The new species, provisionally named Borrelia mayonii, is related to a strain called Borrelia burgdorferi which has long been linked to the disease.

Prior to this finding, the only species believed to cause Lyme disease in North America was Borrelia burgdorferi, the researchers said.

As with B. burgdorferi, researchers believe that B. mayonii is transmitted to humans by the bite of an infected black-legged tick (otherwise known as the deer tick).

Typical symptoms of Lyme disease include fever, headache, rash, neck pain and arthritis in later stages.

Unlike B. burgdorferi, however, B. mayonii causes an illness that appears to be associated with nausea and vomiting, diffuse rashes (rather than a single bull's-eye rash), and a higher concentration of bacteria in the blood, the researchers said.

In a paper published in the journal The Lancet Infectious Diseases, the scientists tested samples from US patients from 2003 to 2014 for evidence of Lyme disease using a method called polymerase chain reaction (PCR).

From 2012 to 2014, the researchers noticed unusual test results from six of 9,000 samples from residents of Minnesota, North Dakota and Wisconsin.

"Using a laboratory-developed test with a method called 'melting temperature analysis,' we detected six specimens that produced a PCR result that was clearly different from B. burgdorferi," said first author of the study Bobbi Pritt from Mayo Clinic in Minnesota.

Based on these findings, the researchers detected the new culprit for the Lyme disease.

They believe that the organism may have only recently emerged in the upper Midwestern US.

"It is possible that this species has been present for even longer but at such low levels that it escaped detection," Pritt noted.

For treatment, the patients described in the study fully recovered using antibiotics commonly used to treat Lyme disease caused by B. burgdorferi.