Prevalence, incidence, and determinants of syphilis in female commercial sex workers in Mexico City.

Abstract

To determine the prevalence and the incidence of serologic markers for syphilis, and the characteristics associated with the risk of infection in female commercial sex workers in Mexico City. To identify female commercial sex workers at greater risk of infection with syphilis. The authors performed a cross-sectional study of 3,100 female commercial sex workers who sought human immunodeficiency virus testing at a National Council on AIDS clinic between January 1992 and April 1993. The authors collected information about socioeconomic and demographic characteristics, history of sexually transmitted diseases, sexual practices, and preventive measures against such diseases. All of the women provided a blood sample for identification of infection markers and in a subgroup of 1,802 women, repeat samples were obtained to estimate the rate of seroconversion to syphilis. Prevalence of syphilis was 8.2%, with an incidence of 2.4 per 100 person years. A positive linear relation between age and time working in commercial sex and prevalence of infection markers was observed. Women with less education, born in states other than Mexico City, and who worked on the street had significantly greater risks of infection with syphilis. Frequency of infection by both estimators is relatively low in the women studied. Characteristics related with periods of exposure such as age and time working in commercial sex, as well as socioeconomic and demographic characteristics, such as place of birth, education, and type of work site, were significantly related to the frequency of infection.