A newly discovered disease-causing bacteria

In addition to cataloging Borrelia burgdorferi infection rates among ticks in the Bay Area, the Bay Area Tick Study revealed the presence of Borrelia miyamotoi in local tick populations. B. miyamotoi is a relatively newly discovered tick-borne parasite related to the Lyme-causing Borrelia burgdorferi (Bb) bacteria, only recently linked to disease in humans.

Like Borrelia burgdorferi, Borrelia miyamotoi is a spirochete or corkscrew-shaped bacteria that travels directly into cell tissue. The first case of human infection by Borrelia miyamotoi was documented in Russia in 2011, and in the US in 2013, though studies showing presence of the bacteria in the ticks in Connecticut date back to 2001 (Krause, Narasimhan, et. al., New England Journal of Medicine, 2013) and the bacteria was first identified in 1995 in ticks from Japan (CDC).  Recently, cases of B. miyamotoi human infection have been reported in Massachusetts and New Jersey.

Lyme-like symptoms

Infection by this bacteria tends to produce symptoms similar to Lyme disease, including fever, headache, fatigue, joint and muscle pain, loss of appetite, disorientation or memory loss, and lack of coordination, as well as more severe conditions of neurological disease.

Borrelia miyamotoi appears to be a common co-infection with the Bb bacteria (see Other Tick-Borne Diseases for more information on co-infections).  B. miyamotoi infrequently produces erythema migrans or skin rash so patients need to be alert to other symptoms.

Common serological tests for Lyme do not detect the B. miyamotoi spirochete, and there is no commercially available test for B. miyamotoi as of yet. Treatment commonly prescribed for Lyme (antibiotics like doxycycline or amoxicillin) is thought to be effective combating B. miyamotoi, though the course and duration of treatment may vary.

More research needed

Recent studies in the US have shown incidence of B. miyamotoi throughout the US, particularly in areas where Lyme disease is endemic, including coastal California (see Bay Area Tick Study).

More research is needed to determine the bacteria’s prevalence, its effects, and how best to treat the infection.

For more information, also see:

Human Borrelia miyamotoi infection in the United States
Correspondence submitted to the editor of the New England Journal of Medicine describing recent studies indicating that Borrelia miyamotoi, a close relation of Borrelia burgdorferi, can be transferred to humans.