Doctors face challenges in diagnosing Borrelia miyamotoi
Life seemed simpler for doctors treating Lyme disease before the discovery of numerous pathogens in ticks. The Centers for Disease Control and Prevention (CDC) now reports that “a single tick can transmit multiple pathogens, including bacteria, viruses, and parasites.”  In fact, between 2004 and 2016, the CDC identified 7 new tick-borne microbes capable of infecting humans.
by Daniel J. Cameron, MD, MPH
Borrelia miyamotoi, the bacteria which causes relapsing fever, is one of the latest threats. The disease was first reported in the United States in 2013 but has become increasingly more common. B. miyamotoi is carried by black-legged ticks, the same ticks that can transmit Lyme disease. One study found that 2% of nymphal ticks collected in 11 states endemic for Lyme disease were infected with B. miyamotoi.
A recent review by Shapiro and Wormser in the Journal of the American Medical Association, points out the concerns associated with this particular tick-borne disease and how its unique presentation can make it challenging to diagnose.
- “This bacterium can be transmitted within the first 24 hours of tick attachment.”
- “The probability of transmission increases with every day an infected tick is allowed to remain attached.”
- While some patients with Lyme disease may exhibit a rash, “patients infected with B. miyamotoi in the United States typically do not have a rash.” But they may present with “a fever in conjunction with headache (96%), myalgia (84%), arthralgia (76%), and malaise/fatigue (82%).”
- There are no diagnostic tests for B. miyamotoi infection that have been approved by the US Food and Drug Administration.
- The fever may be relapsing. [Editor’s note: Fevers often do not relapse.]
- “Laboratory abnormalities include leukopenia (51%) and thrombocytopenia (60%), which are rarely seen in Lyme disease.” [Editor’s note: These are seen in Ehrlichia and Anaplasmosis.]
- “Severely immunocompromised patients may develop chronic meningitis.”
Fortunately, doxycycline and amoxicillin have been shown to effectively treat B. miyamotoi infection in patients, including those who are immunocompromised. [Editor’s note: Long-term outcome studies are needed.)
- CDC Vital Signs, Weekly / May 4, 2018 / 67(17);496–501. https://www.cdc.gov/mmwr/volumes/67/wr/mm6717e1.htm
- Shapiro ED, Wormser GP. Lyme Disease in 2018: What Is New (and What Is Not). Jama. 2018;320(7):635-636.