Surge in Syphilis Cases Attributed Solely to Change in Investigation Method

Reports recently claimed a surge in syphilis cases, but experts argue that this reflects a change in statistical methodology rather than a sudden actual increase in patients. The Korea Disease Control and Prevention Agency (KDCA) managed syphilis through a sample surveillance system, receiving reports only from selected monitoring institutions, but switched to a comprehensive surveillance system in 2024 where all medical institutions report cases. The reporting targets were also expanded to include tertiary syphilis and early latent syphilis, whereas previously only primary, secondary, and congenital syphilis were tracked. On the 19th, the KDCA noted that "cases from the sample surveillance period (2020–2023) and those reported in 2024 and onwards cannot be simply compared."

If only the original criteria—primary, secondary, and congenital syphilis—are compared, figures for 2024 and 2025 stand at 1,519 and 1,182 cases, respectively. These numbers represent a decrease of 13.3% and 32.6%, respectively, compared to 2019 (1,753 cases), which also utilized a comprehensive surveillance system.

A closer look at the total of 2,790 cases in 2024 reveals a similar story. According to the '2024 Syphilis Epidemiological Characteristics' published by the KDCA, the incidence rate was 5.4 per 100,000 people. Of these, early latent syphilis, which shows no actual symptoms, accounted for 1,220 cases (43.7%), nearly half the total. The inclusion of early latent syphilis in the reporting criteria effectively inflated the overall figures.

There is also a misconception that syphilis is a disease imported from abroad and spreading. Based on the '2024 Syphilis Epidemiological Characteristics', infections from abroad totaled only 117 (4.2%).