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First Tests to Screen for Tick-borne Parasite in Whole Blood and Plasma Approved by FDA

For use as donor screening tests on samples from individual human donors, the tests will identify antibodies to Babesia microti in human plasma samples and B. microti DNA in human whole blood samples.

Two tests able to detect antibodies to Babesia microti (B. microti) in human plasma samples and B. microti DNA in human whole blood samples were just approved by the US Food and Drug Administration (FDA). The first test, Imugen Babesia microtiArrayed Fluorescent Immunoassay (AFIA) is able to detect the antibodies in human plasma samples, and the Imugen Babesia microtiNucleic Acid Test (NAT) is able to detect B. microti DNA in human whole blood samples. Both tests are "intended to be used as donor screening tests on samples from individual human donors, including volunteer donors of whole blood and blood components, as well as living organ and tissue donors," according to a statement from the FDA.

Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research explained the importance of the tests in the statement, remarking, "The US blood supply remains the safest in the world thanks in part to the FDA’s ongoing work to enforce standards for blood collection and to identify and respond to potential threats to the nation’s blood supply. While babesiosis is both preventable and treatable, until today, there was no way to screen for infections amongst blood donors. Today’s actions represent the first approvals of Babesia detection tests for use in screening donors of whole blood and blood components, and other living donors.”

Spread by the blacklegged tick, Babesia parasites cause babesiosis, which does not commonly cause symptoms in most individuals who are infected, but can be devastating for some individuals who suffer from severe infection. Although transmission of the virus through blood transfusion is rare, the FDA reports that "it is the most frequently reported transfusion-transmitted parasitic infection in the United States and remains an important concern."

Between 1000 and 2000 cases of babesiosis are reported in the United States each year. Most of these infections occur in the Northeast or upper Midwest portions of the United States.

According the FDA statement, "The investigational use of Babesia donor testing has been in place since August 2012 in selected Babesia-endemic areas under investigational new drug applications. The use of the investigational tests has resulted in the removal of a significant number of infected units from the blood supply. The data collected from this testing and from additional studies performed by the manufacturer prevented the release of hundreds of potentially infectious donations and demonstrated that the tests are effective in screening donors for B. microti infection."

Of note, these tests are not intended for use in the diagnosis of babesiosis infections.

Although no FDA guidance for the testing of donor samples for Babesia currently exists, draft guidance with recommendations for reducing the risk of transfusion-transmitted babesiosis will be released by the FDA later this year.

The approval of the Imugen Babesia microti AFIA and NAT tests was granted to Oxford Immunotec, Inc. Both assays are in-house tests that can only be performed at the Norwood, Massachusetts facility.