Transfusion-associated transmission of babesiosis in New York State.

BACKGROUND: Babesiosis can be life-threatening in immunocompromised individuals. Although the disease is usually transmitted by tick bite, more than 20 cases have been reported of infection transmitted by transfusion of blood or blood components obtained from apparently healthy donors from endemic areas in the United States. This report describes several recent cases of transfusion-transmitted babesiosis in New York State.

STUDY DESIGN AND METHODS: Transfusion-associated incidents of babesiosis infection were identified and investigated. Seroprevalence of babesiosis in healthy blood donors in a highly endemic area was ascertained.

RESULTS: In three incidents, babesiosis was diagnosed in five of eight patients given infected blood: two premature infants, an elderly patient with gastrointestinal bleeding, and two patients with thalassemia. Seroprevalence in blood donors on Shelter Island (Suffolk County, eastern Long Island), a highly endemic area, was 4.3 percent in May 1998.

CONCLUSIONS: Infected donors lived in endemic areas and were asymptomatic with no history of tick bite. Blood collected in January 1997 from one donor was infectious. Those transfusion recipients who were infected were neonatal, elderly, or chronically transfused patients. Babesiosis should be included in the differential diagnosis of febrile illness in immunocompromised recipients of blood transfusion, particularly in the Northeastern United States.