[IgM diagnosis in syphilis serology].

The methods in use for the detection of T pallidum-specific antibodies in human sera are the 19S-(IgM-)FTA-ABS and the IgM-SPHA test. Encouraging results have been obtained with the IgM-ELISA-TP technique using new antigens. The development of the different methods up to the present time are described. The margin of error is low, 3.4% of the 19S-(IgM-)-FTA-ABS results are false-positive and 3.6% false-negative, the respective figures for the IgM-SPAH test are 1% (false-positive) and 8% (false-negative). The agreement with the clinical diagnosis is excellent in the secondary stage (94 to 95% reactivity), the reasons for lower rates in the primary and late phases are discussed. The half-life period of reactivity after adequate treatment amounts to 2 to 6 months in all stages except for the IgM-SPHA test in neurosyphilis, where reactivity remains for 24 months (mean value) due to the production of autoantibodies.