https://immattersacp.org/weekly/archives/2013/07/02/4.htm

New tickborne illness may present as human granulocytic anaplasmosis

Two patients originally diagnosed with human granulocytic anaplasmosis (HGA) were found to have Borrelia miyamotoi infection instead, according to a new case report.


Two patients originally diagnosed with human granulocytic anaplasmosis (HGA) were found to have Borrelia miyamotoi infection instead, according to a new case report.

Researchers in Massachusetts and New Jersey detailed their findings on two patients, one from each state, who presented to primary care outpatient facilities with fever and were subsequently diagnosed with HGA, a tickborne illness. Both patients were eventually hospitalized due to the severity of their symptoms but failed to respond to doxycycline therapy after 24 hours. In addition, no molecular evidence of Anaplasma phagocytophilum, the causative agent of HGA, or of seroconversion to its antibodies was found in either patient. These findings led to further investigation with polymerase chain reaction (PCR), which identified B. miyamotoi. The case report was published in the July 2 Annals of Internal Medicine.

The authors cautioned that co-infection with B. burgdorferi could not be ruled out in one of the patients. However, they concluded that B. miyamotoi infection should be considered in patients who are thought to have HGA but do not respond to treatment with doxycycline, and they noted that such cases involving fever, myalgia, and elevated aminotransferase levels are probably being misdiagnosed and erroneously reported to the Department of Public Health.

“In North American sites, and indeed globally across the Holarctic where Lyme disease and HGA are commonly zoonotic, clinicians need to be aware of this newly recognized pathogen and include B. miyamotoi infection in the differential diagnosis of tick-exposed patients presenting with fever, myalgia, and elevated aminotransferase levels,” they wrote.

The authors of an accompanying editorial urged caution in transitioning agent-specific PCR and serologic tests from the research setting to the clinical laboratory, noting that it seemed most appropriate for public health laboratories, both local and regional, to first work with investigators to develop and offer diagnostic testing to study the disease. However, they said, “In the meantime, B. miyamotoi infection should be included in the differential diagnosis of patients presenting in Lyme disease-endemic areas with unexplained fever, headache, myalgia, elevated hepatic aminotransferase levels, and leukopenia or thrombocytopenia during the summer months, and empirical doxycycline should be considered in severely ill patients.”