Unusual behaviour of serological tests for syphilis in Ugandan Africans.

The fluorescent treponemal antibody (FTA) test developed by Deacon, Falcone, and Harris (1957) and later modified with the absorption procedure by Hunter, Deacon, and Meyer (1964) has contributed much to the better diagnosis and control of syphilis in many parts of the world (WHO Scientific Group Report, 1970). The test combines the sensitivity and specificity of immunofluorescence with easy reproducibility (Mora, 1969) and is now the most popular treponemal test for syphilis (Sparling, 1971). Compared with other serological tests, it is highly sensitive at all stages of the disease (Atwood, Miller, Stout, and Norins, 1968; Gamer, Grantham, Collins, and Roeder, 1968; Knox, Short, Wende, and Glicksman, 1966; Lassus, Mustakallio, Aho, and Putkonen, 1967) and nearly equals the Treponema pallidum immobilization test in specificity (Deacon, Lucas, and Price, 1966; Garner and others, 1968; Goldman and Lantz, 1971). In Uganda and probably the whole of tropical Africa, the FTA-ABS test is not yet available. Reagin screening tests, either the VDRL slide test or the PPR, and the RPCF test for confirmation of treponemal antibodies, are the only tests available. They are cheap and easy to perform, but are not very specific and are less sensitive in late or inadequately treated cases of syphilis (Gillespie and Brown, 1964; Nicholas and Beerman, 1965; Sparling, 1971). This communication reports a comparative assessment of the FTA-ABS, RPCF, Kolmer, and VDRL slide tests in 402 indigenous African subjects with verified or suspected syphilis or miscellaneous conditions. In addition, 163 controls were tested with the FTA-ABS, TPI, and VDRL slide tests.