An increasing incidence of VDRL serononreactors in an eldery, T. pallidum infected population

Changes in the proportion of VDRL nonreactors among the people who had come into contact with Treponema pallidum in the course of their lifetime were assessed within the frame of the Diagnostic Proficiency Program covering serologic laboratories for the detection of syphilis in Croatia. Based on the analysis of the CNIPH serologic laboratory records the paper shows a clear increase in the above share over the past 22 years. Data on 491 infected persons (those reactive to the reference TPHA test), mean age 52.87 years, were analyzed. During 22 years of observation (1976-1998), this proportion rose from 21.92% (1976-1979) through 51.79% (1980-1989) to 64.86% (1990-1998). At the same time, this tendency reveals a considerable decrease in the number of infected persons exhibiting VDRL reaction (i.e. with potentially active late syphilis), which could be ascribed to the ever more effective detection of the infected and to their ever earlier and more efficient treatment.