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February 12, 1982

Posttreatment Serological Response of Biologic False-Positive Reactors

JAMA. 1982;247(6):817-818. doi:10.1001/jama.1982.03320310065035

IN 1980, there were 27,204 reported cases of primary and secondary syphilis in the United States, an increase of 33.4% during the last three years.1 It is well known that certain diseases, immunizations, and febrile states may produce a reaction to a reagin blood test for syphilis in the absence of this disease. In the United States, approximately 45 million persons are tested for syphilis and about 1.4 million have a reaction to reagin test.2 How many have biologic false-positive reactions is unknown. However, in Massachusetts, slightly more than 160,000 blood samples were sent to the state laboratory for the rapid plasma reagin circle-card test (RPR-CT) for syphilis. Approximately 7% were found to be reactive. Further testing of the reactive blood tests with the fluorescent treponemal antibody absorption (FTA-ABS) test disclosed that about 25% had a nonreactive FTA-ABS test, indicating that the patient has a biologic falsepositive reaction.