Background Syphilis and other STIs are prevalent in sub-Saharan Africa, perhaps due to lack of effective curative services. Estimates among pregnant women and in the general population in Zambia range from 6% to 18%, with maternal syphilis contributing to a high number of mid-trimester abortions, still births, prematurity, and morbidity and mortality of the child. Existing evidence suggests that control of syphilis and other ulcerative and non-ulcerative STIs remains one of the key strategies for HIV control. There are no recent studies from Zambia comparing syphilis prevalence with HIV trends.

Objectives To investigate trends in syphilis prevalence using Antenatal Clinic (ANC) sentinel surveillance data, and to validate the findings with population-based data.

Methods The analyses are based on ANC data from 1994 to 2008 from 22 sites. Estimates are compared with data from Zambia Demographic and Health Surveys (ZDHS) 2001/2002 and 2007. Analyses were restricted to women aged 15–49 years and 15–24 years. ORs with 95% CIs were used to test whether the prevalence trends were significant.

Results The overall syphilis prevalence dropped during the period 1994–2008 among both urban and rural women aged 15–49 years from 9.8% to 2.8% and 7.5% to 3.2%, respectively. Provincial variation was observed with a tendency towards a reduction. A sharper decline in syphilis prevalence was observed among women with more years in school than among those with fewer schooling years. A declining trend was also seen among young primi gravid women aged 15–19 years. A comparison of ZDHS 2001/2002 and 2007 findings also showed an overall reduction in syphilis prevalence in the general population.

Conclusions There was an overall reduction in syphilis prevalence and this decline was sharper than the decline in HIV during the same period. In part this could be attributed to the revamping of STI services in the country. Reduction in both HIV and syphilis prevalence could also suggest a reduction in the disease incidence and is likely to partially reflect positive sexual behaviour changes. Provincial variations were striking and need to be further studied to better guide specific STI prevention and control programmes in different geographical settings