Of 206 leprosy patients, 40% (82) were found to have reactive nontreponemal tests for syphilis. Forty percent of these patients (33 of 82) were found to have reactive treponemal tests, either fluorescent treponemal antibody absorption test (FTA-ABS), Treponema pallidum immobilization test (TPI), or both. It was concluded that at least 16% of the leprosy patients studied had some serologic evidence suggestive of a treponemal infection either in the past or at present. Treponemal diseases may be common among leprosy patients, and may account for some of the reactive serologic tests usually called biologic false positive BFP. The FTA-ABS test was found to be more frequently reactive than the TPI among those leprosy patients studied. The rapid plasma reagin (RPR) card test was rather insensitive but seemed more specific than the venereal disease research laboratory test for syphilis (VDRL). Question of false-positive FTA-ABS tests in some of these patients could be neither established nor disproved.
Scotti AT, Mackey DM, Trautman JR. Syphilis and Biologic False Positive Reactors Among Leprosy Patients. Arch Dermatol. 1970;101(3):328-330. doi:10.1001/archderm.1970.04000030072011