Syphilis remains a significant public health issue in Chile, and in 2025, it reached its highest epidemiological level of the last decade.
According to the Abridged Annual Epidemiological Report: Syphilis, Chile 2025, from the Ministry of Health’s Department of Epidemiology, shows that the country reached a historic high of 11,155 diagnoses that year, with a national notification rate of 55.2 cases per 100,000 inhabitants, reinforcing an upward trend that had intensified following the COVID-19 pandemic.
The observed patterns confirm that syphilis remains a priority sexually transmitted infection (STI) for epidemiological surveillance in Chile.
The 2025 increase must be interpreted within the context of a long-term trend. National records had shown a decline in 2020, coinciding with disruptions in access to health services, a drop in medical consultations, and changes in social behavior caused by the pandemic. Subsequently, there was a sustained recovery in case notifications. An analysis of records from the Public Health Surveillance Information System (EPIVIGILA) for the 2018–2022 period had already documented a rise in incidence from 33.6 cases per 100,000 inhabitants in 2020 to 47.9 in 2022. During that period, 38,467 cases were reported, with early-stage syphilis predominating, accounting for 51.6% of the records.
Bacterial vaginosis (BV) and the increased risk of sexually transmitted infection (STI) coinfections
The 2025 report highlights that the disease burden is concentrated primarily among young adults. The 20-to-39 age group accounted for approximately 58% of the cases, and its rate reached 111.3 cases per 100,000 inhabitants—more than double the national rate. Within this segment, individuals aged 30 to 39 also showed a particularly high incidence, at around 103.5 cases per 100,000 inhabitants. These results confirm that Treponema pallidum transmission particularly affects the young, sexually active population, although the infection is not limited to these groups. A rapid increase in cases is observed among adults over the age of 60: 13.9% of total cases involved individuals in this age group, which has shown one of the largest increases in recent years.
The distribution by sex shows a marked male predominance. Approximately two out of every three cases involve men, although trends among women warrant special attention due to the increase recorded in 2025. The rate among women rose by approximately 16% during the year, reaching 38.4 cases per 100,000 inhabitants. This increase is epidemiologically and obstetrically significant because infection during pregnancy can lead to congenital syphilis, miscarriage, stillbirth, preterm birth, and other serious complications for the newborn. Therefore, controlling syphilis in women of reproductive age is a fundamental component of prevention strategies.
The geographical breakdown reveals significant differences among Chilean regions. Tarapacá and Aysén recorded the highest rates in 2025, with approximately 90.3 and 90.1 cases per 100,000 inhabitants, respectively. In the case of Aysén, the increase was especially pronounced: the rate rose from 10.2 in 2021 to 90.1 in 2025. The Metropolitan Region also experienced a considerable increase, going from 41.9 cases per 100,000 inhabitants in 2021 to 54.3 in 2025. Overall, most regions recorded increases during the 2021–2025 period, although exceptions were observed, including Antofagasta and Los Lagos.
These geographic differences are epidemiologically significant because they show that the rise in syphilis is not a phenomenon confined to a specific area of the country.
High rates in northern regions, alongside significant increases in central and southern areas, suggest widespread transmission driven by demographic, social, and behavioral factors, as well as by access to diagnostic and treatment services. Regional variations may also reflect differences in the intensity of screening and reporting; therefore, rates must be interpreted with regard to the functioning of local surveillance systems.
The trends observed during 2025 must also be analyzed within the broader context of STIs. Chile maintains universal surveillance for syphilis and gonorrhea, both of which are notifiable diseases. Ministry of Health guidelines set a goal of reducing the incidence of syphilis and gonorrhea relative to the 2018 baseline and maintaining or lowering the incidence of congenital syphilis—including stillbirths—to 0.5 cases per 1,000 live births.
The rise in syphilis thus presents a challenge that extends beyond individual diagnosis. While the availability of diagnostic tests and effective penicillin treatment makes it possible to prevent many of the disease’s complications, the population-level impact depends on early detection, timely treatment, patient follow-up, and the management of sexual partners. The high proportion of cases among young adults underscores the need for prevention strategies specifically targeting this group.
Overall, the report indicates that 2025 marked a point of major concern regarding the epidemiology of syphilis in Chile. The national rate of 55.2 per 100,000 inhabitants, the prevalence among young adults, the high rates among men, the rise in cases among women, and significant regional disparities create a scenario that demands the simultaneous strengthening of surveillance, early diagnosis, treatment, contact tracing and management, and STI prevention interventions. The trend also highlights the importance of maintaining accessible testing and healthcare services, reinforcing sex education, and promoting proper condom use. Experience from recent years shows that disruptions or reductions in healthcare activity can significantly alter the detection of these infections; therefore, the restoration of surveillance must be accompanied by sustained prevention and control policies.
Ultimately, data from 2025 indicate that syphilis is no longer a problem confined to specific groups but has become an epidemiological challenge of national scope. The sustained rise in rates and their concentration among the young population make it particularly important to intervene before new chains of transmission emerge and, at the same time, to strengthen screening during pregnancy to prevent the increase in sexually transmitted cases from leading to a rise in congenital syphilis.
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