Infectious Patients Surge 4.5 Times... The Truth Behind the Syphilis Epidemic, a Sexually Transmitted Infection [News Seolcham]

(37) 'Statistical Trap' Arising from Changed Reporting Criteria
New Infection Cases Fewer than in 2019
Sample Surveillance in 2020 Led to an 81% Sharp Decline
Syphilis Epidemic in US, Japan, etc... "Be Careful During Vacation Season"

Editor's Note'Seolcham' is a newly coined term meaning to refer to detailed explanations. In [News Seolcham], we aim to pinpoint and explain in more detail the parts of the news that require fact-checking or further explanation.

As the vacation season approaches, fear of syphilis is spreading domestically. This is due to statistics showing a surge in the number of syphilis infection patients. However, the sharp increase in patient numbers is more of a statistical trap caused by changes in the reporting criteria for syphilis patients this year.

The controversial statistic is that syphilis infections have increased '4.5 times' this year compared to last year. According to data confirmed by Seo Mi-hwa, a member of the Democratic Party of Korea, from the Korea Disease Control and Prevention Agency, the number of reported syphilis infection patients from January to August this year reached 1,881. Compared to last year's total number of syphilis patients (416), it appears to have increased sharply.

However, this alone does not mean that syphilis patients have increased 4.5 times. The rapid change in syphilis statistics is largely due to two changes: ① sample surveillance → full surveillance ② changed reporting targets (previously only primary, secondary, and congenital syphilis were reported → currently all primary, secondary, tertiary, latent, and congenital syphilis are reported).

Originally, syphilis was subject to full surveillance, but from 2020 to 2023, it was under sample surveillance for four years and returned to full surveillance this year. This decision was based on the understanding that syphilis can be transmitted over a long period and, if not treated timely, can progress to severe complications. Under full surveillance, all medical institutions diagnosing or detecting syphilis must report within 24 hours. In contrast, under sample surveillance, only designated medical institutions need to report within 7 days, so cases from non-designated institutions are not included in the statistics.

Compared to 2019, when syphilis was also under full surveillance like this year, the number of new infections this year is actually lower. Breaking down the 1,881 syphilis infection patients reported from January to August this year by stage: 679 primary, 316 secondary, 39 tertiary, 9 congenital, and 838 latent cases. In 2019, latent and tertiary syphilis were not reportable, so comparing only the sum of primary, secondary, and congenital cases, the number of syphilis infection patients from January to August 2019 was 1,222, which is higher than this year's 1,004.

During the years 2020 to 2023, when syphilis shifted from full surveillance to sample surveillance, the number of reported syphilis patients sharply decreased. According to the Korea Disease Control and Prevention Agency's annual infectious disease surveillance reports, the number of syphilis patient reports dropped dramatically from 1,753 in 2019 to 330 in 2020, an approximately 81% decrease. Other years recorded 339 in 2021, 401 in 2022, and 416 in 2023.

The Korea Disease Control and Prevention Agency also states, "The increase in syphilis reports in 2024 is due to the change from a sample surveillance system to a full surveillance system, making simple comparisons with previous years difficult."

However, since syphilis is spreading worldwide, caution regarding infection is necessary. Japan, a popular tourist destination visited by 7 million Koreans last year alone, is experiencing a severe syphilis epidemic. The number of syphilis infections exceeded 5,000 in 2017 and reached 13,228 in 2022. The United States also reported 207,255 syphilis patients in 2022.

In South Korea, hospital visits due to syphilis have increased over the past three years. According to the Health Insurance Review and Assessment Service, the number of patients receiving hospital treatment for early syphilis (primary and secondary stages) within one year of infection was 5,954 in 2019, 6,099 in 2020, and 6,293 in 2021, showing an increasing trend.

Regarding syphilis patients by gender, males account for about 78%, which is very high. According to the Korea Disease Control and Prevention Agency's monthly syphilis report for the recent six months (March to August 2024), out of 1,495 total syphilis reports, 1,163 (77.8%) were male. The remaining 22.2% (332) were female. By age group, the highest proportion is among young people: 446 cases (31.2%) in their 20s, followed by 398 cases (27.8%) in their 30s, and 218 cases (15.2%) in their 40s.

Syphilis, a sexually transmitted infection, is mainly transmitted through sexual contact. If not treated early during the primary and secondary stages, when symptoms such as skin ulcers and rashes appear, the disease can progress. Without timely treatment, the syphilis bacterium can invade the eyes, heart, bones, joints, and even the central nervous system, potentially leading to severe cardiovascular complications and death. Pregnant women infected with syphilis can transmit it to the fetus, resulting in miscarriage or stillbirth. Surviving infants with congenital syphilis may suffer from visual or hearing impairments and severe developmental delays.