The prevalence of gestational syphilis in Malawi between 2014 and 2022: spatiotemporal modeling of population-level factors

Chirombo, J., Majamanda, A., Gunsaru, V., Yosefe, S., Ozituosauka, W., Mchoma, C., Morroni, C., Chipeta, E., MacPherson, P. and Freyne, B. (2024) The prevalence of gestational syphilis in Malawi between 2014 and 2022: spatiotemporal modeling of population-level factors. Frontiers in Public Health, 11, 1242870. (doi: 10.3389/fpubh.2023.1242870)

Abstract

Background: Mother-to-child transmission of syphilis remains high especially in the WHO AFRO region with a prevalence of 1.62% resulting in congenital syphilis rate of 1,119/100,000 live births. Elimination efforts can be supported by an understanding of the spatial and temporal changes in disease over time, which can identify priority areas for targeted interventions aimed at reducing transmission.We collated routine surveillance data from health facilities and covariate data from demographic and health surveys done in Malawi between 2014 and 2022. We fitted a Bayesian hierarchical mixed model with spatial and temporally structured random effects to model the Districtlevel monthly counts of maternal syphilis notifications as a function of individual-and District-level predictors. We then generated District-level spatio-temporally explicit risk profiles to estimate the effect of individual-and district-level covariates on maternal syphilis notifications and to identify hotspot areas.Results: Overall, the national prevalence of maternal syphilis increased from 0.28% (95% CI: 0.27 -0.29%) in 2014 peaking in 2021 at 1.92% (95% CI: 1.89-1.96%). Between 2020 and 2022, there was a decline in prevalence, with the greatest decline seen in Zomba District (1.40%, 95% CI: 1.12-1.66%). In regression models, a one percentage point increase in District-level antenatal HIV prevalence was associated with increased maternal syphilis (prevalence ratio [PR]: 1.15, 95% [credible interval] CrI: 1.10-1.21). There was also an increased prevalence of maternal syphilis associated with an increased District-level mean number of sex partners (PR: 1.05, 95% CrI: 0.80-1.37). The number of Districts with high prevalence of maternal syphilis also increased between 2014-2022, especially in the Southern Region, where most had a high probability (approaching 100%) of having high maternal syphilis (defined as relative risk > 1 compared to the standard population of women aged 15-49 years) in 2022.Maternal syphilis prevalence in Malawi shows an increasing upward trend, with an estimated six times relative increase between 2014 and 2022 (0.28% to 1.73%), and strong associations with higher District-level HIV prevalence. Controlling syphilis depends on reaching vulnerable populations at sub-national level which may be disproportionately affected. Our findings support the move to integrate EMTCT of syphilis programs with existing PMTCT of HIV programs.

• Item Type: Articles
• Keywords: maternal syphilis, EMTCT, syphilis prevalence, spatio-temporal model, HIV.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacPherson, Professor Peter
• Authors: Chirombo, J., Majamanda, A., Gunsaru, V., Yosefe, S., Ozituosauka, W., Mchoma, C., Morroni, C., Chipeta, E., MacPherson, P., and Freyne, B.
• College/School: College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Public Health
• Journal Name: Frontiers in Public Health
• Publisher: Frontiers Media
• ISSN: 2296-2565
• ISSN (Online): 2296-2565
• Copyright Holders: Copyright © 2024 Chirombo, Majamanda, Gunsaru, Yosefe, Ozituosauka, Mchoma, M
• First Published: First published in Frontiers in Public Health 11:1242870
• Publisher Policy: Reproduced under a Creative Commons license