Syphilis cases surge across Latin America as PAHO reports 4.2 million new infections

Congenital syphilis reaches ‘alarming’ levels in Uruguay, Brazil

More than 40% of the world’s syphilis cases are now recorded in the Americas, according to the Pan American Health Organization. The region is also seeing increases in HIV and gonorrhea infections, health authorities said.

In Chile, a Health Ministry epidemiological surveillance report released Thursday found that the syphilis rate increased 2.4 times between 2016 and 2025, reaching 55.2 cases per 100,000 people. Cases are concentrated among men ages 15 to 39. Chile’s Public Health Undersecretariat said poor awareness of the risks associated with sexually transmitted infections and low condom use have contributed to the trend. Authorities have also expanded screening and case detection, identifying infections that previously went unreported.

Argentina has recorded a sharp increase. According to the Health Ministry’s latest National Epidemiological Bulletin, 46,779 syphilis cases were reported in 2025, a 75.6% increase from 2022, representing a record rate of 117.2 cases per 100,000 people. The first report of 2026 showed syphilis cases increased 109% compared with previous years, reinforcing a trend that has been rising for more than a decade.

Uruguay’s Public Health Ministry considers syphilis an epidemiological problem that has required nationwide measures. Cases of congenital syphilis, in which the infection is transmitted from mother to fetus, have reached an “alarming” level, according to health authorities. Official data for the first half of 2026 show a 40% increase in reported cases compared with the same period a year earlier. The cumulative incidence rose from 75.17 to 105.19 cases per 100,000 people.

Brazilian Health Ministry officials have raised particular concern about an increase in vertical transmission, when an infection passes from a pregnant woman to the fetus. According to ministry reports, more than 810,000 cases of syphilis among pregnant women were recorded between 2005 and 2025. Experts classify the disease as a persistent epidemic, characterized by consistently high case numbers over time.

Mexico is following a similar trend. The country recorded 18,384 cases in 2024 and 21,617 in 2025.

One of the main challenges in controlling syphilis is that the infection can be asymptomatic. Initial lesions are often painless and may disappear without treatment, creating a false impression that the infection has cleared. Without a diagnosis, an infected person can continue to transmit the disease. Low condom use and the failure to properly treat all sexual partners also contribute directly to the spread of the infection.

The increase in infections coincides with a decline in prevention measures worldwide. According to UNAIDS’ Global AIDS Update 2025, international condom procurement declined 30% between 2016 and 2022 compared with the 2010-2016 period. The agency also reported that government campaigns promoting condom use have declined by as much as 50% since 2010.

Analysts say the rise in syphilis has multiple causes, including lower risk perception among young people, advances in HIV diagnosis and treatment and declining condom use.

“They use it only at the end of intercourse, not throughout the entire sexual encounter, or they use it only on certain occasions or with certain people,” Romina Bustos, a professor of midwifery at Diego Portales University’s School of Midwifery in Chile, told UPI.

Bustos said major advances in HIV diagnosis and treatment have reduced fear of sexually transmitted infections, contributing to a decline in consistent condom use.

David Torres, an epidemiologist and professor in the Department of Public Health at the University of the Andes School of Medicine, said the current trend also reflects a return to levels seen before the COVID-19 pandemic.

“It may also reflect an increase in reporting, greater access to healthcare and people seeking medical attention earlier,” Torres said.

Torres noted that people with syphilis may delay seeking medical care and treatment because symptoms can take time to appear.

“A person can infect multiple sexual partners before developing symptoms, especially if the infection is asymptomatic. When it is not detected in time, it facilitates transmission to others and can even be passed from a mother to a newborn during vaginal delivery,” he said.

Bustos emphasized that the situation is concerning because an untreated sexually transmitted infection can cause serious complications.

“If it is not diagnosed in time, the disease can progress and affect different organs, including the central nervous system, the cardiovascular system and the bones, among others,” she said.

“This problem is already urgent throughout Latin America and the Caribbean. Therefore, we should not wait until the figures become even more serious to implement permanent public policies,” Bustos said.