The US Food and Drug Administration (FDA) on Tuesday finalized guidance on the use of serological tests to reduce the risk of transmission of T. cruzi, a parasite that causes Chagas disease, in blood and blood components.

This guidance supersedes 2010 guidance and finalizes a draft from 2016 that amended the 2010 guidance by expanding its scope to include the collection of blood and blood components for use in manufacturing a product, including donations intended as a component of, or used to manufacture, a medical device; removing the recommendation to ask donors about their Chagas disease histories; and providing a recommendation for a reentry algorithm for certain donors deferred on the basis of screening test results or because they answered "yes" to the Chagas screening question.

Background

Chagas disease, caused by the protozoan parasite T. cruzi, is endemic in Mexico and Central and South Americe. Experts estimate that about 300,000 people unknowingly infected with the parasite reside in the US.

FDA said it received two comments on the 2016 draft, and those comments were considered in finalizing the guidance.

Guidance

The 18-page guidance features recommendations on donor testing, donor deferral, further testing, notification and the reentry algorithm for donors deferred based on screening test results for antibodies of T. cruzi or pre-donation screening questions.

The guidance also notes that it removed the recommendation on asking blood donors about a history of Chagas based on "the low sensitivity and specificity of the donor question, the significant clinical sensitivity of the two currently licensed screening tests (Refs. 13 and 14), the low (0.8%) risk of transfusion-transmitted T. cruzi infection from a seropositive donor (Ref. 11), and the observation that T. cruzi RIPA positive donors are likely not aware of their infection."

FDA instead recommends "that one-time testing alone, without donor questioning for history of Chagas disease, is adequate and appropriate to identify donors at risk for transmission of Chagas disease."

Use of Serological Tests to Reduce the Risk of Transmission of Trypanosoma cruzi Infection in Blood and Blood Components