Enzyme immunoassay for anti-treponemal IgG: screening or confirmatory test?
OBJECTIVE
To review the performance of the Venereal Diseases Research Laboratory (VDRL) test and the Treponema pallidum haemagglutination assay (TPHA) as a combined screen for syphilis to provide a baseline for assessing screening by anti-treponemal IGG EIA.


METHODS
Between 1980 and 1987 all serum samples were screened by both VDRL and TPHA tests. The FTA-ABS test was also used in suspected early primary syphilis, or when one of the other tests was positive. A positive result in a screening test was confirmed by quantitative testing. From 1988 all specimens were screened with an enzyme immunoassay (Captia Syph G) as a single screening test.


RESULTS
Of the 44 primary, 47 secondary, and 38 early latent cases of syphilis, the VDRL and TPHA detected 32 (73%) and 31 (71%) of the primary cases; the combination detected 37 (84%). All 85 cases of cases of secondary and early latent infection were reactive in the TPHA test, whereas the VDRL was reactive in only 68 (80%). EIA had a reported sensitivity of 82% for primary infection.


CONCLUSIONS
EIA can be used as a single screening test for detecting early syphilis because its results are comparable with those of the combined VDRL and TPHA tests. The conventional VDRL test should not be used as a single screening test.
Young
H
H
Department of Medical Microbiology, University Medical School, Edinburgh.
Moyes
A
A
McMillan
A
A
Patterson
J
J
D000907:Antibodies, Bacterial / Q000032:analysis*; D006386:Hemagglutination Tests; D006801:Humans; D007124:Immunoenzyme Techniques; D007074:Immunoglobulin G / Q000032:analysis*; D012680:Sensitivity and Specificity; D013587:Syphilis / Q000276:immunology; D013588:Syphilis Serodiagnosis / Q000379:methods*; D014210:Treponema pallidum / Q000276:immunology*
D000907:Antibodies, Bacterial; D007074:Immunoglobulin G