Treponema pallidum haemagglutination assay in the routine serodiagnosis of treponemal disease.

A passive haemagglutination test using sheep erythrocytes sensitised with Treponema pallidum extract was introduced into syphilis serology by Rathlev (1965, 1967). Shortly afterwards, Tomizawa and Kasamatsu (1966) and Tomizawa, Kasamatsu, and Yamaya (1969) described a similar test, the Treponema pallidum haemagglutination assay (TPHA), and this was further developed as an automated quantitative microtechnique by Cox, Logan, and Norins (1969). An alternative technique in which sensitized fowl erythrocytes are used has been introduced by Sequeira (1973). Evaluation of the TPHA as a confirmatory test for syphilis has shown it to be about equal in sensitivity and specificity to the fluorescent treponemal antibody absorption (FTA-ABS) test, but much simpler to perform. (Logan and Cox, 1970; Garner, Backhouse, Daskalopoulos, and Walsh, 1972; Johnston, 1972). The simplicity of the TPHA makes it attractive as a screening test. We describe here a microtechnique which is convenient for large-scale screening by TPHA and which we have used so far on over 17,000 sera. This report summarizes our experience with the technique, and discusses the place of the TPHA in the serodiagnosis of treponemal disease.