Re-emergence of syphilis in women of reproductive age and its association with the increase in congenital syphilis in Mexico during 2010–2019: an ecological study

BACKGROUND: Syphilis is a sexually transmitted infection that is re-emerging in different parts of the world. This infection can be transmitted during pregnancy, causing neonatal syphilis. The objective of this study was to examine trend in syphilis, congenital syphilis, and neonatal deaths among the Mexican population during 2010-2019. METHODS: An ecological study was carried out to collect information about the incidence of syphilis, the incidence of congenital syphilis, and the incidence of neonatal death from congenital syphilis. The variables were described considering age, sex, Mexican state, and year. Trends across time (calendar year) were analyzed using linear regression, increases were estimated with 95% confidence intervals, and p < 0.05 was considered statistically significant. RESULTS: The incidence of syphilis increased by an average of 0.336 cases/100,000 per year and was higher among women aged 15-19 years (0.693 cases). Cases of congenital syphilis increased from 62 cases in 2010 to 372 cases in 2019; furthermore, the increase in syphilis cases among women aged 20 to 24 years was associated with an increase in cases of congenital syphilis. In 2010, 50% of Mexican states did not report cases of congenital syphilis, but in 2018, only 10% did not report cases of congenital syphilis. Between 2010 and 2018, 83 neonatal deaths were reported, with the highest incidence in 2018 (0.88 deaths/100,000 newborns). CONCLUSION: The incidence of congenital syphilis is increasing in Mexico. As a consequence of the reemergence of syphilis among the population of reproductive age, it is necessary to address and treat syphilis in various population groups.