Lyme disease is the most commonly reported vector-borne malady in the US. Caused by the bacterium Borrelia burgdorferi, it is passed to humans through the bites of infected blacklegged ticks, also called deer ticks. But health officials are now reporting the discovery of a new species of bacteria that also leads to Lyme disease in humans.

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The blacklegged tick – or deer tick – transmits Lyme disease to humans when bacteria are transferred through their bites. A new type of Lyme disease-causing bacteria has been discovered.

Scientists from the Mayo Clinic in Minnesota first identified the new bacterium from six people infected with Lyme disease whose lab tests produced unexpected results.

They report their findings in the journal Lancet Infectious Diseases.

In collaboration with the Centers for Disease Control and Prevention (CDC), the scientists ran genetic testing and found that the new bacterium is closely related to B. burgdorferi.

They named the new type of bacteria Borellia mayonii after Dr. William Mayo, founder of the Mayo Clinic.

From the information the scientists were able to gather on B. mayonii, they have found that the illnesses caused by it are similar to that caused by B. burgdorferi.

For example, like B. burgdorferi, the new bacterium causes fever, headache, rash and neck pain in early stages of infection and arthritis in later stages.

However, the new bacterium is also associated with nausea and vomiting, as well as diffuse rashes, which differ from the recognizable “bull’s-eye” rash typically associated with Lyme disease. Additionally, the scientists observed a higher blood concentration of bacteria in the patients.

“This discovery adds another important piece of information to the complex picture of tick-borne diseases in the US,” says CDC microbiologist Dr. Jeannine Peterson.

Scientists discovered the new species when six samples – from around 9,000 that were drawn between 2012-2014 from residents of Minnesota, Wisconsin and North Dakota who had suspected Lyme disease – contained bacteria that were genetically different from B. burgdorferi.

Fast facts about Lyme disease
  • It is the most commonly reported vector-borne illness in the US
  • It does not occur nationwide; it is concentrated in the Northeast and upper Midwest
  • Untreated Lyme disease can result in fever, rash, facial paralysis and arthritis.

Learn more about Lyme disease

After analyzing the DNA sequences, the researchers discovered that they were from a previously unidentified species.

The researchers say the new bacterium has been found in blacklegged ticks in northwestern Wisconsin, and the likely exposure sites are in north central Minnesota and western Wisconsin.

However, Dr. Bobbi Pritt, director of the Clinical Parasitology Laboratory at the Mayo Clinic, says that although the new bacterium has only just emerged in the upper Midwest, it “is possible that this species has been present for even longer but at such low levels that it escaped detection.”

In blood samples taken from around 25,000 residents of 43 other states, the new bacterium was not identified, and this includes states in the Northeast that are common sites for Lyme disease transmission.

As such, the researchers say B. mayonii is likely limited to the upper Midwest of the US.

In the video below, Dr. Pritt further explains the new findings:

The current tests that detect the DNA of Lyme disease bacteria – called polymerase chain reaction assays (PCR) – also work for B. mayonii, and the antibiotics typically used to treat Lyme disease caused by B. burgdorferi have successfully worked against the new bacterium.

CDC officials recommend that health care professionals who treat people infected with the new species follow the antibiotic guidance issued by the Infectious Diseases Society of America.

Dr. Pritt says “the public should continue to take the recommended precautions against tick bites, as Lyme disease and other tick-borne diseases are well-established in much of the Northeast.”

Ways of preventing Lyme disease include using insect repellent, removing ticks straight away and using pesticides.

The CDC are currently working with state departments in Minnesota, North Dakota and Wisconsin to gain a better understanding of the new bacterium.

Medical News Today previously investigated how worried we should be about Lyme disease.