Syphilis is a bacterial sexually transmitted infection (STI) caused by Treponema pallidum which results in substantial morbidity and mortality, and it is curable. Syphilis is transmitted through sexual contact with the infectious lesions, via blood transfusion or from a pregnant woman to her fetus. Mother-to-child transmission of syphilis is usually devastating to the fetus in cases that were not detected or treated sufficiently early in pregnancy. Maternal syphilis, when untreated, treated late or not treated with penicillin, results in adverse birth outcomes (ABOs) estimated in 50−80% of cases, depending on the stage of syphilis. These ABOs are often severe and include stillbirth (most commonly), neonatal death, prematurity, low birth weight, and congenitally infected infants.
Syphilis can be prevented through safer sex practices including the correct and consistent use of condoms. Many people with syphilis do not have any symptoms or have only minor symptoms that go unnoticed. Identifying infection through laboratory tests and treatment of positive cases will prevent further transmission and adverse pregnancy outcomes including congenital syphilis. Screening can be done using rapid tests that can provide results in less than 20 minutes, allowing for immediate treatment.
When untreated, syphilis lasts many years and goes through different stages. Treatment for syphilis is done with injectable penicillin benzathine, with 1 to 3 doses depending on the stage of the disease. Only penicillin can prevent congenital syphilis. Treatment with penicillin has been hampered by periodic and prolonged shortages of benzathine penicillin in numerous countries, including high-, low- and middle-income countries.
Many people with syphilis do not present symptoms or do not perceive them. Untreated, syphilis lasts many years and is characterized into different stages. Sexual transmission typically occurs during early stages, i.e., up to 2 years after infection.
During the initial phase (primary syphilis), which lasts on average 21 days, a solitary, painless, usually hard and round sore (chancre) appears at the site of inoculation (contact), often in the vagina, penis or anus (but it may also be extra-genital) and may go unnoticed. The chancre heals with or without treatment within 3 to 10 weeks. If untreated, the disease progresses to the secondary stage.
Secondary syphilis is characterized by a rash that can vary widely and mimic other infectious or non-infectious conditions, but characteristically affects the palms and soles. The rash is non-itchy and can be minimal enough to be overlooked. In warm and moist areas of the body, such as the anus and labia, large white or grey raised lesions may develop at the location of the primary chancre (condyloma lata). The symptoms and signs of secondary syphilis spontaneously resolve, even without treatment. Without treatment, the latent stage starts.
Latent syphilis presents no clinical symptoms or signs and the treatment is different from the early phase. After years or decades without treatment, neurological and cardiovascular diseases among others may occur.
Syphilis diagnosis is based on the person’s history, physical examination, laboratory testing and sometimes radiology, as symptoms are not common or noticeable. Identifying asymptomatic infection through laboratory tests and treatment of positive cases will prevent further transmission and adverse pregnancy outcomes, including congenital syphilis. Laboratory tests for syphilis include direct detection of T. pallidum or indirect methods such as serology. Rapid screening and diagnostic tests are also available and can provide results in less than 20 minutes, facilitating immediate treatment initiation.
WHO recommends syphilis to be treated with injectable penicillin (benzathine penicillin G) with 1 or 3 doses, depending on the stage of the disease. WHO has detailed treatment guidelines for syphilis, and one specifically for the screening and treatment of syphilis in pregnancy.
There are currently no diagnostic tests for congenital syphilis. All live or stillborn infants of women with syphilis should be examined for evidence of congenital syphilis. Live-born infants should be examined and tested at birth to define treatment requirement. When indicated, also at monthly intervals for 3 months until the infant’s serology are, and remain, negative, as maternal antibodies can be passively transmitted to the baby during pregnancy.