Epidemiology
Syphilis is a common STI. There were an estimated 8 million cases of syphilis worldwide in 2022.[10] Although there are four stages of syphilis infection, the primary and secondary stages are the earliest, symptomatic stages and are therefore indicators of incident infection.
Syphilis in the US:
In 2023, the incidence rate of primary and secondary syphilis was 15.8 cases in 100,000 population (53,007 new cases).[11] This represents a 10.7% decrease during 2022-2023. In 2023, almost one-third (32.7%) of all reported cases of primary and secondary syphilis occurred in men who have sex with men, which was a 13.4% reduction in cases compared with 2022.[11] This was the first significant decrease in cases of primary and secondary syphilis among men who have sex with men in more than 15 years. The incidence rate of primary and secondary syphilis was 23.6 cases in 100,000 men and 8.1 cases in 100,000 women.[11] Although the case rates are lower in women, they have increased significantly since 2014 (636.4%), with an increase in incidence of 55.3% during 2020 to 2021.[11] In men, the incidence rate was highest in the age group 30-34 years, followed by the age group 25-29 years (incidence was similar in these two age groups).[11] In women, the highest rate was in the age group 25-29 years.[11]
There were no increases in the rate of primary and secondary syphilis among any race or Hispanic ethnicity group during 2022-2023. However, since 2017, incidence rates have increased among all race/ethnicity groups. The greatest increase is observed among non-Hispanic American Indian/Alaska Native people, who had the highest rate in 2023 (58.2 cases in 100,000 population), followed by non-Hispanic black and African American people (39.7 cases in 100,000 population), Native Hawaiian people and other Pacific Islanders (24.3 cases in 100,000 population), those who identified as multiracial (23.5 cases in 100,000 population), Hispanic and Latino people (16.9 cases in 100,000 population), white people (9.1 cases in 100,000 population), and Asian people (4.4 cases in 100,000 population).[11]
In 2023, there were 3882 cases of congenital syphilis; a 2.9% increase from 2020 (from 102.8 to 105.8 cases in 100,000 live births).[11] Since 2014, the number of cases of congenital syphilis has increased 740.3% (from 462 to 3882 cases). These increases are similar to those seen in women of reproductive age (15-44 years).
Between 2020 and 2021 the collection of surveillance data was affected by the COVID-19 pandemic, so short-term trends should be interpreted cautiously.
Syphilis in other countries:
Syphilis has been increasing in Europe since 2011, particularly among MSM.[11] In 2018, there were 33,927 new cases reported across the 29 countries in the European Union (EU) (7.0 cases in 100,000 population). The highest rate was in Malta (17.9 cases per 100,000 population), followed by Luxembourg (17.1), the UK (12.6) and Spain (10.3). The lowest rates (<3 cases in 100,000 population) were in Croatia, Estonia, Italy, Portugal and Slovenia. The incidence rate was 8 times higher in men (12.1 cases in 100,000 population) than in women (1.4 cases in 100,000 population). The highest age and sex-specific rate was in men aged 25 to 34 years (29 cases in 100,000 population).[12]
In London, UK, the number of syphilis diagnoses reported in 2018 (3435), was an increase of 44% since 2014.[13]
In 2018, 60 congenital syphilis cases were reported in 23 EU/European Economic Area Member States.[12] This represents a crude rate of 1.6 cases in 100,000 live births.
In China, where syphilis was virtually eradicated in the 1950s, both the incidence and prevalence of the disease have more than quadrupled from the 1990s to the 2010s.[14] The increases have been attributed to migration from rural communities to urban environments, limited screening for the presence of the disease, lack of adequate partner notification, and a reluctance by the general population to access STI healthcare services.[15]
Use of this content is subject to our disclaimer