Sero-conversion rate of Syphilis and HIV among pregnant women attending antenatal clinic in Tanzania: a need for re-screening at delivery

BACKGROUND: Despite the available cost effective antenatal testing and treatment, syphilis and human immunodeficiency virus (HIV) are still among common infections affecting pregnant women especially in developing countries. In Tanzania, pregnant women are tested only once for syphilis and HIV during antenatal clinic (ANC) visits. Therefore, there are missed opportunities for syphilis and HIV screening among those who were not tested during ANC visits and those acquiring infections during the course of pregnancy. This study was designed to determine the syphilis and HIV seroprevalence at delivery and seroconversion rate among pregnant women delivering at Bugando Medical Centre (BMC). METHODS: A cross sectional, hospital-based study involving pregnant women attending Bugando Medical Centre (BMC) antenatal clinic was done from January to March 2012. Serum samples were collected and tested for HIV and syphilis using HIV and syphilis rapid tests. Demographic and clinical data were collected using a standardized data collection tool and analysed using STATA version 11. RESULTS: A total of 331 and 408 women were screened for syphilis and HIV during antenatal respectively. Of 331 women who screened negative for syphilis at ANC, nine (2.7%) were seropositive at delivery while of 391who tested negative for HIV during ANC eight (2%) were found to be positive at delivery. Six (1.8%) and 23 (9%) of women who did not screen for syphilis and HIV at ANC were seropositive for syphilis and HIV at delivery respectively. There was significant difference of seroprevalence for HIV, among women who tested negative at ANC and those who did not test at ANC (2% vs.9%, P,<0.001). The overall prevalence of syphilis and HIV at delivery was 15 (2.3%) and 48 (7.2%) respectively. Syphilis seropositivity at delivery was significantly associated with HIV co-infection (p < 0.001), male partner circumcision (p = 0.011) and alcohol use among women (p < 0.001). CONCLUSIONS: The current protocol of screening for syphilis and HIV only once during pregnancy as practiced in Tanzania may miss women who get re-infected and seroconvert during pregnancy. Re-screening for syphilis and HIV during the course of pregnancy and at delivery is recommended in Tanzania as it can help to identify such women and institute appropriate treatment.