Highlighting a population-based re-emergence of Syphilis infection and assessing associated risk factors among pregnant women in Cameroon: Evidence from the 2009, 2012 and 2017 national sentinel surveillance surveys of HIV and syphilis

BACKGROUND: Syphilis and HIV can be transmitted from pregnant women to their children and they remain a public health problem in Africa. Our study aimed to determine the trends of seroprevalence of HIV/syphilis co-infection and syphilis infection overtime through the national surveillance system in Cameroon and to explore associated risk factors. METHODS: We conducted cross-sectional studies of HIV and syphilis, targeting each year 7000 first antenatal care (ANC-1) attendees at the same sites during the 2009, 2012 and 2017 sentinel surveillance surveys. Pregnant women were enrolled at their ANC-1, sociodemographic and clinical information were collected. HIV and Syphilis test were performed by serial algorithm as per the national guidelines. Trends were assessed for HIV, syphilis and HIV/syphilis by estimating seroprevalence from cross-sectional studies. Associated risk factors were explored using multinomial logistic regression with 4 outcomes: HIV/syphilis co-infection, HIV infection only, syphilis infection only and no infection. RESULTS: Overall, 6 632, 6 521 and 6 859 pregnant women were enrolled in 2009, 2012 and 2017 respectively. In 2017, a total of 3 901 pregnant women enrolled were tested for syphilis. Almost half of them (47.9%) were living in urban area and were aged less than 25 years (44.7%). While HIV epidemic was on a decline (from 7.6% (95% CI: 6.99–8.28) in 2009 to 5.7% (95% CI: 4.93–6.4) in 2017), a huge significant increase of syphilis prevalence was observed (from 0.6% (95% CI:0.40–0.80) in 2009 to 5.7% (95% CI:4.93–6.40) in 2017). Pregnant women residing in rural areas were more likely to be infected with syphilis than those living in the urban area (aOR = 1.8 [95% CI: 1.3–2.4]). Unmarried pregnant women were three time more likely to be infected by HIV/Syphilis Co-infection than married, cohabiting, widow or divorced pregnant women (aOR = 2.8 [95% CI: 1.3–2.4]). Furthermore; living in Northern region was associated with a lower risk of being infected with HIV (aOR = 0.6 [95% CI: 0.5–0.9]) and Syphilis infection (aOR = 0.6 [95% CI: 0.4–0.9]). CONCLUSION: The epidemiological dynamics of syphilis suggests a growing burden of syphilis infection in the general population of Cameroon. Our findings support the fact that while emphasizing strategies to fight HIV, huge efforts should also be made for strategies to prevent and fight syphilis infection especially among HIV positive women, in rural area, and southern regions.