Syphilis is a bacterial infection caused by Treponema pallidum that results in substantial morbidity and mortality. Syphilis is a sexually transmitted infection (STI) usually spread through contact with infectious sores on the genitals, anus, rectum, lips or mouth, via blood transfusion, or through mother-to-child transmission during pregnancy.

Correct and consistent use of condoms significantly decreases the risk of infection. Mother-to-child transmission of syphilis (congenital syphilis) is preventable and can be achieved through early screening and treatment.

Congenital syphilis can be easily prevented by early detection, prompt and adequate treatment of infected pregnant women.

Syphilis diagnosis is usually based on medical history, physical examination, and laboratory testing. Uncomplicated syphilis can be easily cured with antibiotics, however if left untreated, the disease last for years and cause serious health problems.

Key facts
  • Symptoms vary depending on the different stages of syphilis. Symptoms usually begin 21 days after infection but can range from 9 to 90 days.
  • Key populations are disproportionally affected, and continue to exhibit a high burden of syphilis, which ranges from 1% to 27% in the case of gay men and other men who have sex with men (MSM), and from 0.5% to 14% in female sex workers (2017 data).
  • Mother-to-child transmission may occur if the expectant mother has syphilis. Mother-to-child transmission of syphilis (congenital syphilis) is usually devastating to the fetus in cases where maternal infection is not detected and treated sufficiently early in pregnancy.
  • Approximately 40% of babies born to pregnant women with untreated syphilis can be stillborn or die from the infection.
  • Syphilis can in most cases be easily cured with antibiotics (penicillin). A fetus can also be easily cured with treatment, and the risk of adverse outcomes to the fetus is minimal if the mother receives adequate treatment during early pregnancy – ideally before the second trimester.
PAHO Response

Untreated syphilis increases the risk of transmitting or acquiring HIV by two or three times in some populations.