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Mayo Clinic identifies new Lyme disease culprit

New York Times

Mosquitoes may be receiving all the attention amid the Zika virus epidemic, but they are hardly the only disease vectors to worry about. Researchers at the Mayo Clinic in Rochester, Minn., have discovered a new species of tick-borne bacteria that causes Lyme disease.

The new species, provisionally named Borrelia mayonii, after the clinic, been found only in the upper Midwest but may be present elsewhere.

Six patients with the infection were identified. The patients had symptoms similar to, but not precisely the same as, those caused by Borrelia burgdorferi, until now the only species known to cause Lyme disease in North America.

Lyme disease was diagnosed in the patients with available tests. But available diagnostic screens may be missing others infected with the newly discovered bacteria, the scientists said.

Dr. Bobbi Pritt, the medical director of the microbiology lab at Mayo, where the strain was first detected, recommended that patients with exposure to ticks get antibody and polymerase chain reaction testing for B. mayonii if they are concerned about infection but do not have the bull’s-eye rash.

Because the symptoms vary slightly from those normally seen in B. burgdorferi infection, doctors may not even think to test for Lyme disease, she said.

Only one of six patients had the bull’s-eye rash that is Lyme’s signature — present in up to 80 percent of cases. Three patients had a difused rash, Pritt said.

The new strain adds vomiting to the list of typical Lyme symptoms, which include fever, headache and neck pain. B. mayonii patients also had a higher-thanexpected concentration of bacteria in their blood.

The antibiotic treatment used to treat Lyme disease appears effective against B. mayonii, Pritt said.

In the summer of 2013, a technician in Pritt’s lab noticed some unusual results from a genetic screen of a patient’s bacterial infection. The test suggested Lyme disease, but a closer analysis found a new species of bacteria causing the condition.

It is unclear where B. mayonii came from, Pritt said, though it doesn’t seem to have diverged recently from B. burgdorferi. It may be that the species has always been present, but was picked up only with better detection tools or that the new bacteria are increasing.

“We hope to be able to answer that with more studies,” Pritt said. In Europe, Lyme disease is caused by multiple pathogenic species of Borrelia, said Per-Eric Lindgren, a professor of medical microbiology at Linkoping University in Sweden.

The discovery of the first Borrelia species in more than a decade is “really exciting,” said Lindgren, who wrote a commentary accompanying the report in the Lancet Infectious Diseases.

Although the six patients at Mayo got their diagnoses with typical tests, he said, “normally you’re only able to detect what you are looking for.” Other cases probably are being missed, Lindgren added: “It’s very likely you could make the diagnostic tools better.”

Field studies in Minnesota have shown that one-third to one-half of adult ticks, and one in five young ticks, called nymphs, carry B. burgdorferi, the previously known bacteria. Only 1 percent to 4 percent carry B. mayonii, said Dave Neitzel, the supervisor of the vector-borne disease unit at the state health department.

“This is just another great reason to protect yourself against ticks,” he said.

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