Serological tests in cerebrospinal fluid for congenital syphilis in Central Africa

Serological tests were performed in the cerebrospinal fluid (CSF) of 13 children with active congenital syphilis (presence of specific IgM FTA-ABS antibodies) and of seven seropositive children with no active syphilis (FTA-ABS IgM-negative) born to syphilitic treated mothers in Libreville, Gabon. Antibodies against treponema were measured by the Venereal Disease Research Laboratory test (VDRL), the Treponema pallidum haemagglutination assay (TPHA) and the fluorescent treponema antibody absorption tests (FTA-ABS IgG and IgM). Of the 13 children with active syphilis, seven had a positive FTA-ABS IgG in the CSF. The result of this test was not correlated with the severity of clinical features, CSF protein levels or number of CSF white blood cells. The CSF-TPHA test was positive in four out of 12 children, and the CSF-VDRL test was negative in all the children with active congenital syphilis. One of the seven newborns with mother-transmitted antibodies had a positive FTA-ABS and TPHA in the CSF. These data show that the VDRL is not sensitive enough to diagnose congenital neurosyphilis, and that FTA-ABS or, at least, TPHA are convenient, sometimes with false-positive results, when a sophisticated method of detecting specific IgM in CSF is not available.