Early diagnostics are a vital tool in slowing the rise of syphilis

First recorded in the 15th century in Europe, syphilis has been a significant public health crisis and major stigma for hundreds of years. Caused by the bacterium Treponema pallidum, today syphilis is a preventable and treatable disease most often spread through direct sexual contact.¹ In the 1990s, syphilis was almost eliminated in the United States, but unfortunately, since 2011, the rate of syphilis has increased every year.² 

In fact, in 2024, close to 190,000 cases of syphilis were reported in the U.S., according to the U.S. Centers for Disease Control and Prevention (CDC). The World Health Organization estimates that 8 million adults between 15 and 49 years old acquired syphilis in 2022.^3,4 Cases of congenital syphilis, where a mother passes on her infection to her baby, have more than tripled in the U.S. in recent years, with nearly 4,000 cases reported in 2024 alone. This is the highest number reported in one year since 1994.³ Many people with syphilis do not have symptoms or do not notice the disease, making early diagnosis one of the most effective tools we have in stopping the growing spread of syphilis.⁴ 

Why syphilis cases are increasing

Syphilis is a highly contagious, growing public health threat that needs attention. Patients with the infection are often not aware they have syphilis, because symptoms are often absent or nonspecific. Additionally, there has long been a stigma surrounding syphilis, which has contributed to people avoiding testing or treatment.⁵ Recently, however, other factors, such as inadequate access to healthcare, limited routine screenings, and limited inclusion of general education and disease awareness, have also contributed to the rise in syphilis cases.⁵ 

As with many other sexually transmitted infections (STIs), controlling the spread of syphilis can be challenging. Syphilis commonly enters a latent stage, where a patient experiences no symptoms despite carrying the infection. This stage can last for years without any symptoms, often leading a person to believe they are no longer infected.⁶ Without regular screening, these hidden infections can cause severe health crises, including serious complications for patients and increased spread of the disease.

The most susceptible populations

Any sexually active person can contract syphilis through vaginal, anal, or oral sex without a condom and with a partner who has syphilis. However, syphilis may be more common in certain populations.⁶ For instance, gay and bisexual men are disproportionately impacted by syphilis. People with human immunodeficiency virus (HIV) and certain racial and ethnic minorities may also have a higher incidence of syphilis. These disparities are often due to socioeconomic factors that can make it difficult for sexually active people to stay healthy.⁶ According to the CDC, rates of adult and congenital syphilis among American Indian/Alaska Native (AI/AN) people in 2023 were the highest of any racial or ethnic group. There has also been an alarming increase in rates of congenital syphilis among AI/AN of 5,250% from 2014 to 2023.^7,8 For all populations, though, early diagnosis and treatment are essential.

Why early detection is critical

Syphilis is curable with the right antibiotics, most commonly penicillin. Earlier diagnosis of syphilis can lead to faster treatment, ultimately leading to a decrease in transmission.¹ It can also prevent severe complications associated with untreated syphilis. Without treatment, syphilis can spread to the brain and nervous system (neurosyphilis), the eye (ocular syphilis), or the ear (otosyphilis). The most severe stage of syphilis, tertiary syphilis, occurs between 10 and 30 years after infection and can affect different organ systems, including the heart and blood vessels, the brain, and the nervous system. While most people with untreated syphilis do not develop tertiary syphilis, the damage to internal organs can be life-threatening and can result in death.⁶ 

Additionally, pregnant women with syphilis can spread the infection to their babies, which can have serious risks, including a low-birth-weight baby, a premature birth, or even a stillbirth. At birth, a baby with a syphilis infection may not have signs or symptoms of the disease. Still, if the baby does not receive treatment right away, they may develop serious problems, such as cataracts, deafness, seizures, or even death.¹ Prenatal syphilis screening is vitally important in reducing congenital syphilis. Finally, early diagnosis plays a critical role in curbing antibiotic resistance. By enabling timely and accurate treatment, rapid testing reduces the misuse of antibiotics that can accelerate the spread of drug-resistant syphilis, which is a growing concern.^5,7,9

Advances in syphilis diagnostics

Today, syphilis is primarily diagnosed using serological tests performed on serum or plasma, which fall into two categories: non-treponemal and treponemal tests.¹ Non-treponemal tests measure anti-lipid antibodies produced in response to damaged host cells and lipids on the surface of Treponema pallidum. Because these antibodies are not necessarily specific to the bacterium, their presence can indicate active syphilis or other conditions, including autoimmune diseases such as lupus.¹⁰ Treponemal tests detect antibodies specific to Treponema pallidum antigens. However, these antibodies can persist after treatment, making it challenging to distinguish active infection from latent disease or past, resolved infection.¹⁰ The CDC recommends using both test types together to accurately diagnose syphilis and differentiate active, untreated infections from previously treated cases.¹⁰

Recent advances in these diagnostics include fully automated tests that improve efficiency, minimize human error, and enable high-throughput testing.¹⁰ There are also now at-home tests available for syphilis screening, which can help mitigate some of the stigma associated with syphilis testing. Patients should still, however, consult their healthcare providers if they think they have a syphilis infection.¹⁰ Among the tools available to curb the global rise of syphilis, early diagnosis remains the most critical. Prompt detection enables timely treatment, limits transmission, and helps prevent severe health complications. 

Additionally, comprehensive sexual education, affordable and accessible testing services, and routine screening protocols for high-risk groups can help reduce undiagnosed cases and reduce the stigma. As syphilis rates continue to climb, expanding access to testing, raising awareness and adopting new diagnostic technologies will be essential to reversing this public health trend.

References

1. Salomè S, Cambriglia MD, Montesano G, Capasso L, Raimondi F. Congenital syphilis: A re-emerging but preventable infection. Pathogens. 2024;13(6):481. https://doi.org/10.3390/pathogens13060481. 
2. Sexually Transmitted Infection Surveillance 2022. Centers for Disease Control and Prevention (CDC). Published 2023. Accessed February 6, 2026. https://www.cdc.gov/sti-statistics/media/pdfs/2025/09/2023_STI_Surveillance_Report_FINAL_508.pdf.   
3. Sexually Transmitted Infections Surveillance, 2024 (Provisional). Centers for Disease Control and Prevention. September 24, 2025. Accessed February 6, 2026. https://www.cdc.gov/sti-statistics/annual/index.html.
4. Syphilis Fact Sheet. World Health Organization. May 29, 2025. Accessed February 6, 2026. https://www.who.int/news-room/fact-sheets/detail/syphilis.
5. Zheng Y, Ye K, Ying M, et al. Syphilis epidemic among men who have sex with men: A global systematic review and meta-analysis of prevalence, incidence, and associated factors. J Glob Health. 2024;14:04004. doi:10.7189/jogh.14.04004.
6. Hufstetler K, Llata E, Miele K, Quilter LAS. Clinical updates in sexually transmitted infections, 2024. J Womens Health (Larchmt). 2024;33(6):827-837. doi:10.1089/jwh.2024.0367.
7. About Syphilis. Centers for Disease Control and Prevention. January 30, 2025. Accessed February 6, 2026. https://www.cdc.gov/syphilis/about/index.html.
8. Reilley B, Hoover A, Leston J. Hidden in plain sight: Syphilis inequities among American Indian and Alaska Native people, 2022-2023. Am J Med. 2025;138(7):1106-1109. doi:10.1016/j.amjmed.2025.02.037.
9. Lieberman NAP, Reid TB, Cannon CA, et al. Near‑universal resistance to macrolides of Treponema pallidum in North America. N Engl J Med. 2024;390(22):2127-2128. doi:10.1056/NEJMc2314441.
10. Papp JR, Park IU, Fakile Y, et al. CDC laboratory recommendations for syphilis testing, United States, 2024. MMWR Recomm Rep. 2024;73(1):1-32. doi:10.15585/mmwr.rr7301a1.