Understanding syphilis: a curable yet rising threat
09 Dec 2024
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Syphilis
Syphilis has affected the global population for centuries with the first epidemic reported in Naples, Italy in 1495. From very early on, syphilis has been stigmatised. Joseph Grünpeck (1473-1532), a German physician contracted syphilis in the early 1500s, and provided the following description.
So cruel, so distressing, so appalling that until now nothing more terrible or disgusting has ever been known on this earth.
Fast-forward 400 years, and syphilis is curable. However, the devastating effects of syphilis on the foetus of a pregnant woman, known ascongenital syphilis, has become a significant public health issue, as rates of syphilis continue to increase globally.
The bacterium
Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum (T. pallidum) subspecies pallidum. There are three other human diseases caused by different subspecies of T. pallidum. T. pallidum subspecies pertenue is the causative agent of yaws, T. pallidum subspecies carateum causes pinta and T. pallidum subspecies endemicum is the bacterium that causes bejel.
Transmission
Syphilis is the only sexually transmitted infection, with yaws, pinta and bejel transmitted via direct contact with a lesion in an infected individual.
Syphilis is predominantly transmitted through direct contact with the lesion or mucous membrane of an infected individual during vaginal, anal or oral intercourse. Although less common, syphilis can be transmitted by infected blood or non-sexual contact with a person who has an infected lesion.
The transmission of syphilis to a foetus can occur at any time during pregnancy, although syphilis is not transmitted via breast milk.
Incubation period
The incubation period of syphilis ranges from 10 to 90 days, with an average period of three weeks.
Infectious period
Syphilis occurs in multiple stages (described in Clinical Presentation below). It is most infectious during the primary and secondary stages when lesions are present. During this period, the risk of transmission can be up to 50% via sexual contact.
If left untreated, syphilis us the most infectious during the first two years after the initial infection, with the highest period of infectivity occurring in the first 12 months. After two years, transmission via sexual contact becomes uncommon.
The unborn baby of a pregnant woman with untreated primary or secondary syphilis has a risk of infection close to 100%. If a syphilis infection is left untreated for more than one to two years prior to a pregnancy, there is a 77% chance of giving birth to an uninfected infant; however it can still lead to a 12% risk of a stillbirth, a 9% risk of neonatal death, a 2% risk of giving birth to an infected infant.
Epidemiology
Globally syphilis cases have been on the rise, with 8 million people infected in 2022, an increase from 7.1 million in 2020. There were 700,000 cases of congenital syphilis in 2022, equating to 523 per 100,000 live births. Since 2016, there has been an increase in incidence and prevalence of active syphilis in males and females between the ages of 15 to 49 years of age.
Australia has been battling a rise of syphilis cases since 2011. Cases of syphilis with a duration of less than two years have increased (excluding 2020 and 2021). This year, 5,130 cases have been diagnosed in Australia. In 2023, 6552 cases were diagnosed compared to just 1332 diagnosed cases in 2011.
Aboriginal and Torres Strait Islander people are disproportionately represented in syphilis notifications, with rates seven times higher than those of non-Indigenous people over the past 12 months. However, the greatest proportion of syphilis cases have been reported in non-Indigenous men, predominately living in urban areas, within the same period.
Australia has seen a steady increase in reported cases of congenital syphilis. From just six cases reported in 2011, the number rose to 20 cases in 2023, the highest record since national surveillance began in 1991. To date, nine cases of congenital syphilis have been recorded in 2024.
Clinical Presentation
The clinical presentation of syphilis is categorised into three stages, primary, secondary and tertiary.
Primary
Primary syphilis typically presents with a lesion, known as chancre. It appears 2-3 weeks after exposure as a hard painless ulcer that weeps and occurs at the site of initial exposure. Lesions usually resolve spontaneously, even if untreated.
Secondary
The next stage is known as the secondary stage, which begins 4-6 weeks after infection in untreated patients. Most patients feel unwell and develop a generalised rash over the body, that classically also involves the palms of the hands and soles of the feet.
During this stage, patients can present symptoms such as headache, fatigue, swollen lymph nodes (lymphadenopathy), low-grade fever, sore throat, rash, whitish or grey flat-topped lesions in warm moist areas (condylomata lata) and hair loss (alopecia).
If left untreated, these symptoms can last for up to three months or more. After this stage, the patient enters the early latent phase, characterised by an infection acquired within two years that no longer causes symptoms. The majority of untreated patients remain in this stage for the rest of their lives.
Tertiary
Tertiary syphilis occurs in approximately one-third of patients who have had untreated syphilis. This stage can occur 5-20 years after the initial infection and some patients can develop skin cardiovascular or central nervous system disease.
Congenital syphilis
Congenital syphilis occurs when the syphilis bacteria crosses the placenta during pregnancy and infects the foetus. This can occur at any time during pregnancy. Congenital syphilis can result in intrauterine foetal death, stillbirth, neonatal death or a premature baby.
HIV and syphilis
Infection with Human Immunodeficiency Virus (HIV) can change the behaviour and appearance of primary and secondary syphilis and increase the risk of central nervous system disease.
Testing
It is recommended that individuals be tested for syphilis during asymptomatic STI checks, and during pregnancy,
There are multiple steps involved to diagnose an individual with syphilis.
Blood test
Firstly a blood (serology) test is undertaken to screen for specific antibodies, which are proteins produced by the immune system against T. pallidum.
If the screening test is positive, a second T. pallidum specific antibody test, the Treponema pallidum haemagglutination (THPA) test, is performed. A positive result on the second test almost certainly indicates that a patient been exposed to T. Pallidum at some point.
To determine whether the infection is active or current, a rapid plasma reagin (RPR) test is performed. This test measures the amount or quantity of antibodies (RPR) in the blood, and this RPR titre reflects the activity of syphilis-causing bacteria.
Swab
A polymerase chain reaction (PCR) test can also be undertaken by swabbing a patient’s lesion to detect genetic material from the bacteria. If a swab returns a positive result, bloods tests would then be conducted to help determine if this is a new case of primary syphilis or a reinfection.
Point-of-care (POC) testing
The Determine Syphilis TP™ test is currently the only syphilis point-of-care (POC) test registered by the Therapeutic Goods Administration (TGA) in Australia. It involves collecting a small sample of blood via a finger prick to check for infection. This test cannot differentiate between an active or past infection. However, the advantages of the POC tests are that it uses only a small volume of blood; it does not need specialised skills to perform the test, and only takes a few minutes to set up. They also provide a rapid turnaround time of 15 minutes for results. For these reasons, POC tests are very useful in field settings with transient patient populations, enabling syphilis to be diagnosed and treated or at least flagged for follow-up during the patient’s first visit.
Self-testing
Syphilis self-test kits are available overseas, allowing patients to test themselves at home. However, no self-test kits for syphilis are currently approved by the TGA in Australia.
Currently, the routine serology or PCR testing that is available cannot differentiate between syphilis, yaws or pinta, as all are caused by different subspecies of T. Pallidum. Clinical history, presentation and epidemiological history need to be reviewed when interpreting test results to distinguish the different disease entities.
Management
Long acting benzathine penicillin is the medication for the treatment of syphilis. The preparation, dose and length of treatment is dependent on the stage of syphilis at the time of clinical presentation. Early referral or discussion with a specialist is recommended.
Other management advice for patients include the following:
- No sexual contact for seven days after treatment has commenced, or until the treatment course is completed and symptoms have resolved, whichever is later
- No sexual contact with partners from the last three months (primary syphilis), six months (secondary syphilis) or 12 months (early latent) until the partners have been tested and treated if necessary
- Contact tracing and presumptive treatment of partners will be required for partners whose last contact was within three months and
- Notify public health unit if required as per national notifiable disease guidelines.
Test of cure
It is recommended that all patients undergo a follow-up review, including a repeat RPR testing 6-8 weeks after completing treatment. Retesting is recommended if reinfection is suspected.
Public Health
Syphilis and congenital syphilis are preventable, making it crucial to maintain a low threshold for testing. Cases of congenital syphilis reflect a failure of the health system. It is essential that pregnant women be tested for syphilis during their pregnancy, treatment provided if diagnosed, as well as testing, and treatment of partners.
There is also concern about the interaction between HIV and syphilis, due to the shared transmission routes and syphilis enhancing the transmission and acquisition of HIV.
Prevention
Prevention of syphilis encompasses education, screening, treatment and partner notification.
It is recommended that individuals:
- Always use condoms with condom-safe lubricants (for example water or silicone based) during vaginal and anal sex
- Always use dental dams during oral sex
- Avoid sexual activity if you or your sexual partner are unwell, especially if they have symptoms of syphilis
- Syphilis is included in all STI check-ups, with additional to testing recommended for high-risk groups.
Pregnant women should be tested for syphilis as least twice during pregnancy, at the first antenatal visit and again at 26-28 weeks gestation. For women in outbreak areas in Australia or who are at high risk, testing is recommended up to five times during pregnancy.
Global Initiatives
Multiple national and global initiatives are underway to eliminate syphilis. A framework has been developed by the World Health Organization (WHO) to implement triple elimination of mother-to-child transmission of HIV, syphilis and hepatitis B. This framework aims to guide efforts in expanding service delivery from eliminating mother-to-child transmission of HIV, to triple elimination of HIV, syphilis and Hepatitis B.
The Global Health Sector Strategies (GHSS) for HIV, viral hepatitis and STIs for the period 2022-2030 has outlined six strategic directions for STIs. These include indicators and targets for reducing new cases of syphilis and congenital syphilis, increasing the percentage of pregnant women attending antenatal care and ensuring treatment for those who test positive, particularly in priority populations.
It is the responsibility of everyone to protect our future generations and ensure that syphilis is eliminated.
References
- CDNA Series of National Guidelines | Syphilis – CDNA National Guidelines for Public Health Units
- CDC STI treatment guidelines | Syphilis - STI Treatment Guidelines (cdc.gov)
- WHO | Global health Observatory | Data on syphilis (who.int)
- Science Museum, London |The history of Syphilis Part One: cause and symptoms | Science Museum
- Australian STI Management Guidelines for use in Primary Care | STI Guidelines Australia | Australian STI Guidelines website
- National Communicable Disease Surveillance Dashboard | Dashboard NINDSS Portal (health.gov.au)
- World Health Organisation |
- Introducing a framework for implementing triple elimination of mother-to-child transmission of HIV, syphilis and hepatitis B virus
- World Health Organisation | Global Health Sector Strategies on, respectively, HIV, viral hepatitis and sexually transmitted infections for the period 2022-2030 (GHSS)
- Library of Congress | Home | Library of Congress (loc.gov)
- American Public Health Association |Control of Communicable Diseases Manual 20th Edition
