Development of Warm-Antibody Autoimmune Hemolytic Anemia in Babesiosis

HealthDay News — Warm autoimmune hemolytic anemia (WAHA) develops in some patients after babesiosis, with patients with asplenia at increased risk, according to a study published in the New England Journal of Medicine.

Anne E. Woolley, MD, from Harvard Medical School in Boston, and colleagues conducted a retrospective cohort study of all patients with babesiosis from a single center from January 2009 to June 2016. Data were extracted on covariates of interest, including any hematologic complications occurring within 3 months after diagnosis and treatment of babesiosis.

The researchers found that 18 of the 86 patients with a babesiosis diagnosis were asplenic. Six patients developed WAHA at 2 to 4 weeks after babesiosis diagnosis, by which time all patients had experienced clinical and laboratory responses to antimicrobial babesiosis treatment, which included clearance of Babesia microti parasitemia. All 6 patients were asplenic (<.001), and positive direct antiglobulin tests for immunoglobulin G and complement component 3 were seen for them; all these patients had warm autoantibodies. There was no alternative explanation for clinical hemolysis. In 4 of the 6 patients WAHA required immunosuppressive treatment.

“We documented post-babesiosis WAHA in patients who did not have a history of autoimmunity; asplenic patients appeared to be particularly at risk,” the researchers write.

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Woolley AE, Montgomery MW, Savage WJ, et al. Post-babesiosis warm autoimmune hemolytic anemia [published online March 9, 2017]. N Engl J Med. 2017; 376:939-946. doi: 10.1056/NEJMoa1612165