Borrelia miyamotoi, a distant cousin of B. bergdorferi, was first identified in Japan in the mid-1990s. It has a distinct molecular "fingerprint," and seldom produces the characteristic target-shaped erythema multiforme rash seen with B. bergdorferi. It is, however, carried by deer ticks, and can cause a spectrum of non-specific symptoms including high-fever, muscle and joint pain.
Over the last decade, there has been a surge of research and clinical experience showing that B. bergdorferi often has "help" in producing the Lyme syndrome. Ticks may carry several pathogens simultaneously, including Bartonella, Babesia, Ehrlichia, and Mycoplasma, each of which may contribute to the symptom cascade.
B. miyamotoi was identified in a Russian outbreak of severe fevers in 2011, roughly 16 years after it was initially identified in Japan. While the organism was found in US ticks as early as 2001, there were no North American reports of human infection.
That changed earlier this month, with the first published US case in the New England Journal of Medicine, on Jan. 17 (Krause PJ, et al. N Engl J Med. 2013;368(3):291-3). The new pathogen has also been detected in 18 in people in New England, New York and New Jersey who'd been hospitalized with acute fevers and symptoms suggestive of Lyme, but who tested negative for B. bergdorferi.
The new bug was identified using a test developed by Imugen in collaboration with researchers at Tufts University.
Peter J Krause, MD, an epidemiologist at Yale School of Public Health who published the NEJM report believes the syndrome caused by B. miyamotoi is distinct from Lyme disease, mainly in that it often presents with a recurring fever. Patients, "have a fever for a few days, they get better and it goes away for maybe a week or two, and then it comes back again," he said in an interview on the Yale website.
Dr. Krause's team has studied human blood specimens from Lyme-endemic areas archived from 1999-2010, testing for the presence of GlpQ antigen which is reactive to B. miyamotoi (and other relapsing fever spirochetes) but not B. burgdorferi.
They found that 21% (n=3) of 14 patients investigated for a late spring or summer viral-like illness tested positive for this antigen. They also detected the antigen in 3% of 273 patients with Lyme disease or suspected Lyme disease, and 1% of 584 healthy people living in areas where Lyme disease is endemic.
B. miyamotoi has been found in deer ticks throughout New England, the Midwest, and also the far western states. So far, there have been no reports of human infections west of the Rockies, but Dr. Krause expects that will change sooner or later.
That said, he stressed that "people shouldn't panic about this." B. miyamotoi should be treated with the same antibiotic protocols as would be used against B. bergdorferi.