Analysis of Trends and Factors Associated with the Prevalence of Syphilis in Brazil, 2018–2023

Abstract Introduction Sexually Transmitted Infections (STIs), primarily transmitted through unprotected sexual contact, can be influenced by factors such as age. The notification of these cases may have been affected by the COVID-19 pandemic, including a reduction in the demand for healthcare services and underreporting. Methods This observational study analyzed notification data for HIV, syphilis, and viral hepatitis in Brazil between 2018 and 2023, obtained from the Ministry of Health's Notifiable Diseases Information System (SINAN). The objective was to describe temporal trends and the distribution by age, sex, race/skin color, and geographic regions, with an emphasis on underreporting during the pandemic. Results Between 2018 and 2023, Brazil recorded 77,004 HIV cases, with a significant drop in 2020. Acquired syphilis totaled 949,739 cases, with an increase until 2022 and a decrease in 2023. Gestational syphilis peaked in 2022 (83,033 cases) and declined in 2023 (35,741). Congenital syphilis recorded 142,115 cases between 2011 and 2023, with the highest incidence in children up to 6 days old. Viral hepatitis showed a similar pattern. The highest incidence rates were observed among men, people of mixed race/skin color, in the Southeast and Northeast regions, and in the 20-29 age group. Conclusions The pandemic hindered access to healthcare services, contributing to the underreporting of STI cases. Health access disparities are evident, particularly between the Southeast and Northeast regions. Although both are the most populous in the country, they differ in infrastructure and access to healthcare services, with the Southeast being better equipped. The most affected age group was young adults, with higher incidence among men and people of mixed race/skin color, highlighting the urgent need for public policies to address these inequalities and expand access to healthcare. Key messages • Syphilis cases rose until 2022, then dropped in 2023, likely due to underreporting during COVID-19. Young adults, men, and mixed-race people were most affected. • Health disparities and pandemic-related barriers limited STI reporting, stressing the need for equitable policies and expanded access to care across regions.