A tick-borne illness that presents with undifferentiated flu-like symptoms similar to those seen in patients with Lyme disease and other such ailments is cropping up in the Northeastern United States.
According to a recent Annals of Internal Medicine article(annals.org), two patients -- one a 61-year-old man in Massachusetts and the other an 87-year-old New Jersey man -- presented with signs and symptoms suggesting human granulocytic anaplasmosis (HGA), which is caused by the rickettsia-like bacterium Anaplasma phagocytophilum carried by deer ticks in that region.
The presumptive diagnosis proved false, however, when both patients failed to respond within 24 hours to conventional doxycycline treatment -- as would be expected with HGA -- and tested negative for A. phagocytophilum. Eventually, investigators detected Borrelia miyamotoi.
"The presence of B. miyamotoi DNA in the peripheral blood and the patients' eventual therapeutic response to doxycycline are consistent with the hypothesis that their illness was due to this newly recognized spirochete," the authors concluded. "Samples from tick-exposed patients acutely presenting with signs of HGA, but who have a delayed response to doxycycline therapy or negative confirmatory test results for HGA, should be analyzed carefully for evidence of B. miyamotoi infection."
- A tick-borne illness that presents with undifferentiated flu-like symptoms similar to those seen in patients with Lyme disease is cropping up in the Northeastern United States.
- Patients present with what appears to be to be human granulocytic anaplasmosis (HGA), but after a delayed response to conventional doxycycline treatment, further evaluation reveals Borrelia miyamotoi infection.
- Samples from tick-exposed patients who present with signs of HGA but who have a delayed response to doxycycline therapy or negative confirmatory test results for HGA should be analyzed carefully for evidence of B. miyamotoi infection.
Patient No. 1 -- the Massachusetts man -- presented in 2012 with acute-onset fever and shaking chills for 48 hours before admission, followed by worsening severe frontal headaches, photophobia, myalgia and arthralgia. Although he had no frank gastrointestinal symptoms, he had anorexia and was unable to consume adequate fluids. He also reported chest pain that was not associated with cough, dizziness or syncope. The patient was admitted and his chest pain resolved the following day; however, he continued to experience drenching sweats, as well as episodes of fever with shaking chills and headache. After four days of intravenous doxycycline, his fever broke and he was released on an oral regimen of the antibiotic. At his one-week follow-up, his symptoms had resolved.
Patient No. 2 was admitted in June of 2011 after two days of "severe fatigue, malaise, and (fever) associated with profound prostration." Although he became unsteady on his feet and also had chills, he did not experience chest pain or headache. The patient -- who was treated for babesiosis in 2010 -- "responded within 48 hours to intravenous fluids, bed rest and doxycycline loading with 200 mg intravenously every 12 hours" and was discharged from the hospital on the same oral doxycycline regimen as patient No. 1. He, too, made a full recovery.
According to the study authors, physicians and other health care professionals in the Northeastern United States, where Lyme disease is endemic and Rocky Mountain spotted fever and other tick-borne issues are rare, often diagnose HGA in such patients.
"Similar cases of fever, myalgia and elevated aminotransferase levels have probably occurred elsewhere in the United States where deer ticks are common and are attributed to HGA even with a delayed response to doxycycline treatment but never confirmed by specific laboratory assays," said the authors. "The prominent laboratory finding of elevated hepatic aminotransferase levels … suggests that, unlike the agent of Lyme disease (Borrelia burgdorferi), B. miyamotoi may have a predilection for the liver.
"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."
In accompanying editorial(annals.org), John Branda, M.D., and Eric Rosenberg, M.D., noted that similar U.S. and Russian cases further delineate the clinical syndrome associated with B. miyamotoi infection in immunocompetent adults. However, several questions remain to be answered, they said.
"In particular, the full spectrum of illness needs to be defined," said the two authors. "To date, the description of B. miyamotoi infection is based on the presentation of severely ill hospitalized patients, and whether severe illness is typical remains to be determined."
The authors also pointed out that as the body of literature describing the infection grows, increased demand for diagnostic tests can be expected from patients and clinicians, especially considering that effective therapy may be available.
"It seems most appropriate for local and regional public health laboratories, along with investigators, to develop and offer diagnostic testing for the purpose of studying the disease," they said. "Once the infection is better understood, diagnostic testing can transition to the clinical laboratory to support the care of individual patients.
"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."