FDA OKs First Tests to Detect Tickborne Parasite in Whole Blood and Plasma

Megan Brooks

March 07, 2018

The first screening tests for antibodies to Babesia microti in human plasma samples and B microti DNA in human whole blood samples have been approved by the US Food and Drug Administration (FDA).

The Imugen B microti Arrayed Fluorescent Immunoassay (AFIA) detects the antibodies in human plasma samples, and the Imugen B microti Nucleic Acid Test (NAT) detects 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," the FDA noted in a news release.

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

"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," Peter Marks, MD, PhD, director of the FDA's Center for Biologics Evaluation and Research, said in the release. 

"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," Marks added.

Babesiosis is caused by Babesia parasites transmitted by Ixodes scapularis ticks, also known as blacklegged or deer ticks. B microti is the main species that causes infection in the United States. According to the FDA, about 1000 to 2000 cases of babesiosis are reported in the United States each year, mostly in the Northeast and upper Midwest during warm months.

Babesia can also be transmitted by transfusion of blood or blood components collected from an infected donor. According to the US Centers for Disease Control and Prevention, while bloodborne transmission of babesiosis is thought to be uncommon, it is the most frequently reported transfusion-transmitted parasitic infection in the United States.

The FDA says blood donor testing for Babesia has been used on an investigational basis since August 2012 in selected Babesia-endemic areas under investigational new drug applications and has led to 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," the agency said. 

The new Imugen tests are not intended for use in the diagnosis of babesiosis.

The FDA granted priority review for the Imugen B microti tests. Priority review status is granted to applications for products that, if approved, would be a significant improvement in the safety or effectiveness of treating, diagnosing, or preventing a serious condition.

There currently is no FDA guidance for testing donor samples for Babesia. However, the agency said it will issue draft guidance with recommendations for reducing the risk for transfusion-transmitted babesiosis later this year.

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