[Passive hemagglutination test in the serodiagnosis of syphilis]

Passive haemagglutination test with pathogenic Treponema pallidum antigen in the serodiagnosis of syphilis, carried out on 752 sera (518 syphilitic patients and 234 subjects without evidence of syphilis) showed a greater general sensitivity as compared the cardiolipin tests and complement fixation test with Reiter protein antigen, and lower, to immunofluorescence (FTA--ABS). Its specificity is relatively lower than that of the cardiolopin and treponemal tests. Associated with the cardiolipin test it may be preferably used for the detection of syphilis, and moreover, passive haemagglutination may confirm the diagnosis in case of weak positive results with the FTA--ABS test. The latter is, however, essential for problem cases.