Surreal illustration of the resurgence of syphilis.

Syphilis: Understanding Its Resurgence and Prevention

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Nico Varela in Health & Wellness November 2026 • 3 min read.

"Explore the reasons behind the re-emergence of this old foe and what you can do to protect yourself and others."


Syphilis, caused by the bacterium Treponema pallidum, is a sexually transmitted infection (STI) that has seen a troubling resurgence in recent years. Once thought to be under control, this 'old foe' is back, posing a significant public health challenge globally. Understanding syphilis, its transmission, and prevention is more crucial than ever.

The World Health Organization (WHO) estimates that millions of new cases occur each year. Syphilis can have devastating consequences if left untreated, including damage to the cardiovascular and central nervous systems, and can even be fatal. Pregnant women with untreated syphilis can transmit the infection to their fetuses, leading to congenital syphilis, which causes significant health problems and infant mortality.

This article provides a detailed overview of syphilis, from its causes and symptoms to its treatment and prevention strategies. We'll explore the factors driving its re-emergence, particularly among high-risk groups, and discuss the latest approaches to combatting this infectious disease.

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The Continuing Syphilis Burden

The CDC identifies chlamydia, syphilis, and gonorrhea as reportable sexually transmitted infections for which it provides the most recent national data. The World Health Organization describes syphilis as a curable infection caused by Treponema pallidum that can be transmitted through oral, vaginal, and anal sex, during pregnancy, and through unsafe blood transfusions. If untreated, it can persist for many years and cause serious health problems, while untreated, late-treated, or inadequately treated maternal syphilis can result in adverse birth outcomes.

What Causes Syphilis and How Is It Transmitted?

Surreal illustration of the resurgence of syphilis.

Treponema pallidum is typically transmitted through sexual contact with an infected individual. The bacterium enters the body through minor cuts or abrasions in the skin or mucous membranes. Syphilis can also be transmitted from a pregnant woman to her fetus during pregnancy or childbirth.

It's important to know that syphilis is not spread through casual contact, such as sharing utensils, toilet seats, or touching doorknobs. The primary modes of transmission are:

  • Sexual contact (vaginal, anal, or oral sex)
  • Mother-to-child transmission (MTCT) during pregnancy
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Expanding Clinical Evidence

Recent research includes a narrative review that analyzed Centers for Disease Control and Prevention data from 2020 through 2024 using the National Notifiable Sexually Transmitted Infections Surveillance System to evaluate syphilis trends in the United States. A systematic review of nodular secondary syphilis searched PubMed and Embase through Elsevier and collected 144 published cases of nodular syphilis. A separate case report described syphilitic Charcot arthropathy involving the foot in an Asian patient, whose cerebrospinal fluid showed a VDRL titer of 1:8 and a positive syphilis CSF immunoglobulin G test.

Limits of Prevention and Diagnosis

Syphilis prevention remains constrained by the absence of a vaccine. Historical experience also shows that prevention strategies can depend on broader conditions: a review reports that changes in sexual behavior were more achievable in the 1980s because of the impact of HIV infection and the lack of an effective treatment. Current diagnostic reviews emphasize both the advantages and limitations of testing technologies for adults and newborns, alongside the need to update screening recommendations to reduce or eliminate transmission.

Stages, Follow-Up, and Treatment Options

Syphilis is a systemic disease caused by Treponema pallidum, and its stages are defined by clinical findings that guide treatment and follow-up. One clinical review reports that titers should decline fourfold within six months after treatment of primary or secondary syphilis, and within 12 to 24 months after treatment of latent or late syphilis. Treatment research is also examining alternatives to benzathine penicillin G: NIAID convened a workshop in February 2024 on alternative therapies for adult syphilis, neurosyphilis, and syphilis in pregnant persons and infants.

There is currently no vaccine available to prevent syphilis, making education and awareness about transmission risks essential for prevention.

What Can We Do to Stop the Spread of Syphilis?

Syphilis remains a significant public health challenge, but with increased awareness, timely testing, and effective treatment, its spread can be controlled. By focusing on prevention, early detection, and comprehensive care, we can work towards a future where syphilis is no longer a threat to individual and public health.

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Screening and Emerging Risk Assessment

A 2026 study is reevaluating the clinical utility of three syphilis testing algorithms amid increasing incidence and persistent prevalence. It examines cases from a large hospital in China with concurrent Treponema pallidum electrochemiluminescence immunoassay, T. pallidum particle agglutination, and toluidine red unheated serum test results. Research on machine learning has also identified a gap: previous reviews had not provided a comprehensive synthesis of machine-learning performance across HIV, syphilis, gonorrhea, and chlamydia or included a meta-analysis of machine-learning approaches for STIs.

Burden and Diagnostic Complexity

A study published in 2023 assessed the global, regional, and national burden of syphilis from 1990 to 2019 using disability-adjusted life-years and prevalence. Broader perspectives on sexually transmitted infections emphasize that case studies and real-world examples can show the lived experiences of people dealing with these diseases and the factors shaping their journeys. A clinical dual-case report further illustrates how syphilis can create diagnostic challenges because of its diverse clinical manifestations.

What the historical trend shows

The U.S. trend reversed after a period of decline: the earliest, most infectious stages fell sharply during the 1990s, then increased in the following decade. The figures describe primary and secondary syphilis rates, not all infections or every setting.[1]

The China figures tell a distinct regional history: cases rose after an earlier period when the disease was nearly eliminated. They do not by themselves explain why the increase occurred.[1]

The paper describes a window during incubation in which transmission to sexual contacts may be interrupted through prophylactic treatment. This is a finding about a possible intervention opportunity, not evidence here of its measured impact.[1]

What constrains interpretation of the resurgence

  • The paper notes that migrants may face barriers to insurance, medical facilities, and social welfare, which can affect access to care.[1]
  • The paper argues that surveillance is needed to detect outbreaks and assess intervention strategies; its discussion does not establish which strategies work best.[1]

The review's focus on people with syphilis and higher-risk groups

PopulationPeople with syphilis and groups at high risk for syphilis[2]
Times cited164[2]

How the reported patterns compare across settings

The U.S. history in the paper is a reversal from a low rate around 2000 to a higher rate by 2013, while China’s account describes a rise after near elimination earlier in its history.[1]

Questions a follow-up could resolve

  • How do barriers to health services shape the observed patterns among migrants and other groups identified as being at high risk?[1] [2]

Sources

  1. Syphilis: Re-emergence of an old foe (Europe PMC, 2016)
  2. Syphilis: Re-emergence of an old foe (Shared Science Publishers OG, 2016)

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.15698/mic2016.09.523, Alternate LINK

Title: Syphilis: Re-Emergence Of An Old Foe

Subject: Biochemistry, Genetics and Molecular Biology (miscellaneous)

Journal: Microbial Cell

Publisher: Shared Science Publishers OG

Authors: Lola V. Stamm

Published: 2016-09-05

Everything You Need To Know

1

What exactly causes syphilis, and how does it spread from one person to another?

Syphilis is caused by the bacterium *Treponema pallidum*. It's primarily transmitted through sexual contact with an infected person via small cuts or abrasions on the skin or mucous membranes. Mother-to-child transmission (MTCT) can also occur during pregnancy or childbirth. It's crucial to understand that syphilis isn't spread through casual contact like sharing utensils or touching doorknobs.

2

Why is the resurgence of syphilis considered a major public health issue?

The resurgence of syphilis is a significant public health concern because, if left untreated, it can lead to severe health complications. These include damage to the cardiovascular and central nervous systems. In pregnant women, untreated syphilis can result in congenital syphilis in their babies, causing significant health issues and even infant mortality. The World Health Organization estimates millions of new cases each year, highlighting the urgent need for increased awareness, testing, and treatment.

3

Is there a vaccine available to prevent syphilis, and if not, what are the best ways to protect myself?

Unfortunately, there is currently no vaccine available to prevent syphilis infection. Prevention relies heavily on education and awareness regarding transmission risks. Safe sex practices, such as consistent condom use, and regular testing, especially for high-risk groups, are essential for controlling the spread. Early detection through screening and prompt treatment with antibiotics are the most effective strategies available.

4

What are the major factors that are contributing to the continued spread of syphilis?

Several factors contribute to the ongoing spread, including a lack of awareness about the disease and its symptoms, insufficient access to testing and treatment, and risky sexual behaviors. Certain populations, such as men who have sex with men (MSM), may be disproportionately affected. Addressing these factors requires a multi-faceted approach involving public health campaigns, increased funding for testing and treatment programs, and targeted interventions for high-risk groups. Further research into the social determinants of health and behavior is also needed.

5

What steps can be taken to effectively control and reduce the spread of syphilis?

Controlling syphilis requires a comprehensive approach focused on prevention, early detection, and effective treatment. This includes promoting safe sexual practices, increasing access to testing, ensuring prompt treatment for those infected, and implementing public health campaigns to raise awareness. Focusing on high-risk populations, such as through targeted outreach and screening programs, is also crucial. Continuous monitoring of syphilis rates and trends is necessary to adapt and refine prevention strategies.

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