Transfusion-related babesiosis of concern in the U.S., study finds

Rates of babesiosis related to blood transfusions are of concern in the U.S., according to a recent study from the Centers for Disease Control and Prevention.

Babesiosis is transmissible through tick bite or blood transfusion. While tickborne transmission mainly occurs in seven states in the Northeast and upper Midwest, transfusion-associated cases can occur anywhere. Depending on a patient's age and general health, Babesia infection can range from asymptomatic to severe, leading to nonspecific flu-like symptoms, hemolytic anemia, and complications such as multiorgan dysfunction and death. No screening test is currently approved for blood donors, and donors without symptoms may not know they have the infection.

To examine rates of transfusion-associated Babesia infection in the U.S. since 1979, the authors reviewed data from the CDC, health departments, blood collection and transfusion services, other health professionals, and the medical literature. One hundred fifty-nine cases of Babesia infection were identified, 139 of which (86%) were found to be transfusion-related. These infections occurred during all four seasons of the year in 19 states, with a mean patient age of 65 years (range, 1 to 94 years). Eighty-seven percent of the cases occurred in the seven main babesiosis-endemic states, and 77% of cases occurred between 2000 and 2009.

The authors acknowledged that they had no follow-up data on the identified cases, and that some of the cases may have been related to tickborne transmission. However, they concluded that babesiosis should be considered in patients with unexplained fever or hemolytic anemia, regardless of region or time of year, and that donor-screening strategies should be developed to decrease the risk for transfusion-related transmission.

“The increasing recognition of transfusion cases strengthens the impetus for screening strategies that mitigate the transmission risk, including testing approaches implemented under FDA-approved protocols and longer-term strategies with development of a high-throughput Babesia screening assay,” the authors wrote. Their findings were published early online Sept. 5 by Annals of Internal Medicine.