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Title
Prevalence and correlates of active syphilis and HIV co-Infection among persons aged 15 - 59 in Zambia: Results from the Zambia population-based HIV impact assessment (ZAMPHIA) 2016
Presenter
Lloyd Mulenga
Authors
H. Solomon1,2, A. Moraes1,3, D.B. Williams4, A.S. Fotso5,6, C.B. Ndongmo7, L. Mulenga1,8,9, ZAMPHIA Project Team
Institutions
1Ministry of Health Zambia, Lusaka, Zambia, 2National Health Research Authority, Lusaka, Zambia, 3Zambia National Public Health Institute, Lusaka, Zambia, 4Centers for Disease Control and Prevention, Atlanta, United States, 5ICAP at Columbia University, New York, United States, 6DPS University of the Witwatersrand, Johannesburg, South Africa, 7Centers for Disease Control and Prevention, Lusaka, Zambia, 8University Teaching Hospital, Lusaka, Zambia, 9University of Zambia, School of Medicine, Lusaka, Zambia

Background: Prior studies have suggested sexually transmitted infections, such as syphilis, are associated with an increased risk of transmission of the HIV virus. However, no study has measured the population-level prevalence and predictors of co-infection in Zambia.
Methods: We use data from the 2016 ZAMPHIA, a national household survey that included the DPP® Syphilis Screen & Confirm Assay (Chembio) for active syphilis and Alere Determine? and Uni-Gold? rapid HIV tests, per national algorithm. Bivariate and multivariate logistic regression models were developed to assess associations between co-infection and selected socio-demographic and sexual behavior variables. For the multivariate analysis, those infected with both active syphilis and HIV were classified as co-infected, and the comparison group is those who had no infection. Due to the complex survey design, all reported figures account for the survey design and are weighted.
Results: A total of 19,114 individuals aged 15-59 responded to the individual interview and had a valid syphilis and HIV test. Among this sample were 10, 972 females and 8, 142 males. The national prevalence of active syphilis was 3.0%. Prevalence of active syphilis was highest among females (3.4%), those ≥25 years of age (3.9%), and respondents who reported ≥2 sexual partners in the last 12 months (5.3%). Sexually active HIV-positive persons had a higher prevalence of active syphilis compared to those who were HIV-negative (9.6% vs. 2.1%). The national prevalence of HIV/syphilis co-infection was 1.3% (95% CI 1.1, 1.5). Co-infection was higher among females living in urban areas (aOR =3.1, 95% CI=1.9, 5.0) and females who had an early sexual debut (before age 15 years) (aOR =1.7, 95% CI=1.0, 3.0). Co-infection was also high among both men and women who engaged in transactional sex in the past 12 months (aOR=2.3 (95% CI= 1.1, 5.2) and 4.1 (95% CI= 1.7, 9.8), respectively).
Conclusions: These findings show high prevalence of HIV/syphilis co-infection in Zambia and the need for the scale up of syphilis screening and treatment, particularly among HIV-infected adults. Additionally, these results can be used by syphilis and HIV prevention programs to target populations most at risk for co-infection, specifically those engaging in transactional sex.


Table 1. Active Syphilis Infection and HIV and Syphilis Co-infection among ZAMPHIA 2016 respondents aged 15-59
[Table 1. Active Syphilis Infection and HIV and Syphilis Co-infection among ZAMPHIA 2016 respondents aged 15-59 ]