New Report Describes Rare Case of Transfusion-Transmitted Anaplasmosis

A Maine woman developed a rare case of transfusion-transmitted human granulocytic anaplasmosis (TT-HGA) after receiving a transfusion with a leukoreduced red blood cell (RBC) unit, according to a new case report in Transfusion.

HGA is caused by the bacterium Anaplasma phagocytophilum and is transmitted to humans through the bite of infected black-legged ticks (Ixodes scapularis) and western black-legged ticks (Ixodes pacificus). Symptoms can include fever, headache, muscle aches, fatigue, nausea, abdominal pain and cough. They typically appear within 1–2 weeks after a tick bite.

In this case, the 64-year-old patient received weekly RBC transfusions to treat severe anemia secondary to multiple myeloma, chronic kidney disease and gastric adenocarcinoma with gastrointestinal bleeding. Nine days after the recipient’s last transfusion, her physician reported the possible infection. The patient was tested for tick-borne illnesses due to persistent fevers, new and worsening thrombocytopenia and transaminitis. After testing a blood sample by PCR for Ehrlichia and Anaplasma species, clinicians identified A. phagocytophilum and the patient was treated with doxycycline to resolve the infection. The recipient died from complications of known advanced malignancies a month later.

A lookback investigation identified the implicated donor: a female in her 70s, healthy and physically active, with no underlying medical issues. The donor provided post-donation information and stated that she removed a non-engorged tick from her body approximately one week before the donation. One week after donation, she began experiencing fatigue. Two weeks later, she visited her doctor with increasing achiness and headaches. A blood sample collected from the donor and tested for a tick panel identified A. phagocytophilum by PCR while testing negative for Babesia microti PCR and Borrelia burgdorferi serology. The donor was prescribed two weeks of doxycycline treatment.

Investigators collected a follow-up sample about two months after donation of the implicated unit and 42 days after the donor completed the antibiotic treatment. The sample tested positive for A. phagocytophilum IgM (1:80) and equivocal for IgG (1:64), suggesting a recent infection. The donor was deferred from blood donation for three months after the completion of antibiotic treatment.

The authors emphasized that while blood transfusion is a regulated process with multiple safety measures, pathogens like A. phagocytophilum may still pose a risk due to limitations in screening tests and the potential for subclinical manifestations. Post-donation monitoring of donors for symptoms and subsequent infections is essential to promptly identify and address potential risks associated with transfused blood units, they said.

Moving forward, the authors believe that targeted testing for Anaplasma in endemic areas, akin to screening for Babesia, could enhance blood safety by identifying potential donors with recent infections. Moreover, they emphasized that continued surveillance and adherence to reporting regulations are crucial for tracking cases and assessing the evolving risk of TT-HGA, particularly considering its potential severity in immunocompromised patients.

Additional information about Anaplasma phagocytophilum is available in AABB’s Emerging Infectious Diseases (EID) Fact Sheets. The recently updated EID Fact Sheets assist blood collectors, hospital transfusion services and prescribing clinicians understand and investigate possible transfusion-transmitted infections.