Patients from Massachusetts, Rhode Island, New Jersey, and New York who presented to primary care or urgent care clinics or emergency departments during 2013 and 2014 with fever and whose physicians had suspicion for tick-borne illness had whole blood samples submitted to IMUGEN laboratories for assessment of infection due to various tick-borne pathogens (B. burgdorferi, B. miyamotoi, Babesia microti, Anaplasma phagocytophilum) using real-time PCR. In addition, serologic assessment of antibodies to B. miyamotoi and B. burdorferi was performed.
Ninety-seven patients (0.8% of total tested) with positive PCR for B. miyamotoi DNA were identified. (By comparison, 3.1% contained B. microti DNA, 1.4% A. phagocytophilum DNA, and 1.7% B. burgdorferi DNA.) The majority of cases of B. miyamotoi infection occurred in May-September of both years. Of the patients with positive B. miyamotoi PCR results, 51 had sufficient medical records available for review. The mean age of patients was 55 years. Ninety-six percent presented with fever, 96% with severe headache, 84% with myalgia, 76% arthralgia, 82% malaise/fatigue, 8% rash, 6% gastrointestinal symptoms, 6% cardiac/respiratory symptoms, and 8% neurologic symptoms. Approximately one half of the patients had leukopenia, thrombocytopenia, elevated ALT/AST, or various combinations of these abnormalities. Twenty-four percent of patients required hospital admission. All patients responded clinically to empiric treatment with doxycycline.
An EIA to detect antibodies to a B. miyamotoi recombinant glycophosphodiester phosphodiesterase (rGlpQ) antigen was developed. At initial presentation, only 16% of patients had IgM or IgG antibodies present, and this increased to 78% of convalescent phase samples. Interestingly, only 20% of patients demonstrated IgG or IgA class antibodies, even in convalescent samples. B. miyamotoi patients commonly demonstrated antibody reactivity to B. burgdorferi in the EIA test, but only 10% of patients demonstrated diagnostic reactivity in B. burgdorferi immunoblot assays (suggesting that some of these patients may have been co-infected with both B. miyamotoi and B. burgdorferi).
COMMENTARY
Since the original description of human cases of B. miyamotoi infection in Russia in 2011,1 sporadic cases have been identified in the Netherlands and Japan, and beginning in 2013, cases have been identified in New England.2,3 The current study suggests that B. miyamotoi not uncommonly causes a febrile illness in the Northeastern United States, with similar clinical features as A. phagocytophilum (formerly known as granulocytic Ehrlichiosis) and may be almost as common.
One minor criticism of this study is that it was retrospective and included only symptomatic patients with high pretest probability of having a tick-borne illness. Further studies will be of interest to characterize the prevalence of this disease in the population and to determine the frequency of less severe illness and asymptomatic infection. It is of note that the deer tick (Ixodes dammini) and the black-legged tick (Ixodes scapularis) are the vectors for B. burgdorferi, B. microti, and A. phagocytophilum, as well as the Powassan deer tick virus. Apparent co-infection with B. burgdorferi and B. miyamotoi was seen in this study, and it is likely that co-infection with B. miyamotoi and these other tick-borne pathogens will likely be increasingly recognized. Since molecular diagnostic tests for most pathogens are not generally available with a short turn-around time, prompt empirical administration of doxycycline remains important in the management of these patients.
REFERENCES
- Platonov AE, et al. Humans infected with relapsing fever spirochete, Borrelia miyamotoi, Russia. Emerg Infect Dis 2011;17:1816-1823.
- Chowdri HR, et al. Borrelia miyamotoi infection presenting as human granulocytic anaplasmosis: A case report. Ann Intern Med 2013;159:21-27.
- Krause PJ, et al. Human Borrelia miyamotoi infection in the United States (letter). N Engl J Med 2013;368:291-293.
ABSTRACT & COMMENTARY: It often goes undetected by physicians. Here are the reasons.
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