Tracking — and Tackling — the Recent Resurgence of Syphilis

This notorious sexually transmitted infection (STI) with a long and inglorious history is seeing a new surge in cases. What’s behind the rise and how can healthcare providers help stem the spread?

Since first reported in Europe during the 15th century, syphilis has carried with it significant health risks and social stigma. Speculation and assumptions about its origins and nature of transmission created long-standing associations and questions about personal morality and issues of public health. Today, the epidemiology of syphilis is well understood by the medical community. However, the social implications of this infamous STI remain deeply rooted and continue to create barriers to testing and treatment. This article will explore the recent surge in worldwide syphilis cases, and discuss new opportunities to reduce risks and reverse the trend.

Most often spread through direct, person-to-person sexual contact, syphilis is a preventable and treatable infection caused by the Treponema pallidum (TP) bacterium. There are four stages of syphilis—primary, secondary, latent, and tertiary—each with its own clinical presentations. At the primary stage, the disease first appears as an often-painless sore at the location where the bacteria entered the body. Left untreated, many patients progress to the secondary stage with more visible rashes and symptoms such as fever, fatigue, sore throat, weight loss, hair loss, and headache. Treatment with the antibiotic benzathine penicillin G during the primary and secondary stages is essential to halting the progression of the disease and to achieve a cure.

The latent stage of syphilis can last for years without showing clinical symptoms. Additionally, latent syphilis is not transmitted sexually but can be vertically transmitted to a fetus. Thus, it’s critical that latent syphilis be treated to prevent vertical transmission and complications. If left untreated, syphilis may progress to the tertiary stage, putting people at risk of permanent damage to multiple organs, such as heart and blood vessels, eyes, as well as the brain and nervous system. Tertiary syphilis can take 10-30 years to develop after initial infection, and the damage can be fatal. 

Syphilis was well controlled and close to elimination in the United States during the 1990s. However, according to the US Centers for Disease Control and Prevention (CDC) report, Sexually Transmitted Infections Surveillance, 2022, there was a nearly 80% increase in syphilis cases during the five years spanning 2018-2022. In addition, the 207,255 cases of syphilis in 2022 were the highest number of reported infections in 70 years. Perhaps most alarming is the increase in the number of reported congenital syphilis cases identified in newborns. With more than 3,700 congenital syphilis cases reported in United States in 2022, the rate of increase in the past decade has skyrocketed 937%. 

Worldwide, there were 8 million new cases of syphilis reported in 2022, according to the World Health Organization, including 700,000 cases of congenital syphilis. Country by country, the data shows similar concerning trends to those seen in the United States. Key indicators of the growth of syphilis cases include:

• In 2022, reported cases of syphilis in the United Kingdom reached their highest level since 1948
• 14 of 29 European Union countries reporting cases in 2022 experienced a 25% increase from 2021
• Malta had the highest rate worldwide in 2022 with 24.2 cases per 100,000 people
• Canada experienced a 389% increase in syphilis cases between 2011 and 2019
• Rates of infection in Australia more than doubled between 2015 and 2022

Given the serious nature of the disease, its highly contagious nature, and that carriers are not often aware of their infection status in the primary and latent stages, syphilis is a growing global threat that demands the attention and vigilance of healthcare professionals and individuals alike. 

The stigma surrounding syphilis has long been among the top reasons why people do not seek testing and treatment, as well as the lack of specific symptoms. However, more recently, socioeconomic factors such as inadequate access to healthcare, limited routine screenings, and less inclusion of general education and understanding about the disease have all played a part. In the United States specifically, government funding for STD prevention and education has been reduced or remained stagnant over the past 20 years, further contributing to the lack of awareness. 

Many socioeconomic factors were also exacerbated by the COVID-19 pandemic, making healthcare and regular screening even more difficult to attain for at-risk populations. The healthcare system has yet to fully recover from the impacts, and so the same challenges these groups faced before the pandemic continue to plague the system. 

In addition, the decrease of safe sexual practices and the increase in substance abuse are linked to the rise of syphilis rates.  Another possible factor in the increase of syphilis cases is the recent US shortages of the antibiotic penicillin; the supply could not meet the demand for syphilis treatment.  

While there are several possible factors contributing to the newly rising rates of syphilis, the solutions to stemming the spread are well known to the healthcare community. Testing, treatment, and prevention are still our best defense for regaining control of syphilis worldwide. This is also why the CDC recommends screening all asymptomatic men and women who are at increased risk of STI, as well as all pregnant women at the first prenatal visit. The CDC also recommends additional testing for at-risk populations based on sexual history, HIV status, and other factors.

In early 2024, the CDC updated the Laboratory Recommendations for Syphilis Testing and provided recommendations for tests that can support a diagnosis of syphilis, particularly for serologic tests. The CDC recommends that treponemal tests and nontreponemal tests must be used in conjunction for the diagnosis of syphilis following either the traditional or the reverse algorithm.

Recently, QuidelOrtho™ Corporation received US Food and Drug Administration (FDA) clearance for its VITROS syphilis assay (a treponemal test)—which is run on the Vitros® platforms to detect the presence of antibodies to Treponema pallidum-specific antigens. This test can be used together with a nontreponemal test to aid in the diagnosis of syphilis infection. The VITROS syphilis assay offers healthcare providers a fully automated test that can improve workflow efficiency, minimize human errors, and offer high throughput testing, especially for laboratories with high testing volumes. 

Adding another tool in the fight to reduce syphilis, the FDA also recently authorized the First To Know® syphilis test, a new at-home syphilis test for consumer use, from NOWDiagnostics. This test may help increase initial screenings for individuals suspected of syphilis, as well as overcome some of the privacy issues and stigmas associated with the disease. Positive test results by this assay must be followed by additional laboratory testing through a healthcare provider to confirm a diagnosis of syphilis.  

With greater awareness and preventive measures, expanded testing options, and improved access to healthcare, the world can once again regain control over the scourge of syphilis and stem the rise of infection. It’s a challenge the system has faced before, and, unlike the recent COVID-19 pandemic, the solutions are already available and have proven to be effective in the past. Bringing together the resources of public and private interests, global and community health organizations, and laboratory and clinical care professionals is an essential step to uniting behind this important mission to create a healthier future for all. 

For more information, go to www.quidelortho.com.