Widespread Borrelia miyamotoi Tick-borne Fever Found in US
Janis C. Kelly
June 12, 2015
Borrelia miyamotoi disease (BMD), a tick-borne infection that can cause more severe symptoms than Lyme disease, was first reported in the northeastern United States in 2013 but is becoming more common and should be considered in all areas where deer tick–transmitted infections are endemic, according to a case-series published online June 9 in the Annals of Internal Medicine.
The researchers suggest that BMD might be almost as common as human anaplasmosis among tick-exposed patients who present with fevers in the endemic areas, and they recommend that it be included in routine differential diagnosis protocols.
The timing of BMD peak incidence suggests that, unlike the transmission of Lyme disease pathogen Borrelia burgdorferi, the new infection might be transmitted by unfed larval ticks, who acquire it by transovarial transmission from the infected female tick. This has immediate clinical and public health implications.
In an accompanying editorial, Peter J. Krause, MD, from the Yale School of Public Health and Yale School of Medicine, New Haven, Connecticut, and Alan G. Barbour, MD, from the University of California, Irvine, write, "Bites from larval deer ticks have not been considered as a health threat, but this needs to be reevaluated. Larval transmission of B. miyamotoi has implications for checking for ticks and continuing tick precautions even after the risk for Lyme disease has abated."
Patients Appeared "Toxic," Were Suspected of Having Sepsis
Presenting symptoms typically included fever, myalgia, influenza-like illness, headache, or rash. The authors write, "Patients presented with acute headache, fever, and chills and were often found to have leukopenia, thrombocytopenia, and elevated aminotransferase levels, mimicking human anaplasmosis infection. Patients were commonly described as appearing 'toxic'; more than 50% were suspected of having sepsis, and 24% required hospitalization. The headaches were most commonly described as severe, resulting in head computed tomography scans and spinal taps in 5 patients."
Laboratory investigations showed that 14% of the patients with BMD were coinfected with B burgdorferi. The study authors comment that although sera from patients with acute BMD often show reactivity to B burgdorferi on enzyme immunoassay testing, this is rarely confirmed by immunoblot. They write, "This finding is clinically relevant because a patient presenting with an acute 'summer fever' and no rash and testing positive by whole cell antigen serologic test for Lyme disease could actually be infected with B. burgdorferi, B. miyamotoi, or both. However, sera from patients with BMD generally do not react to B. burgdorferi antigens in [immunoglobulin G or immunoglobulin A] tests, which is partly consistent with what has been previously reported for a small number of case patients with BMD."