Syphilis is a bacterial infection caused by the organism Treponema pallidum that, if left untreated, can lead to serious health complications. Classified as a sexually transmitted infection (STI), it progresses through several distinct stages. Since the infection can manifest with sores on or around the mouth, many people wonder about the possibility of acquiring syphilis through casual contact such as kissing.
Transmission Risk from Oral Contact
Transmission of syphilis through kissing is generally rare. The bacterium Treponema pallidum requires direct contact with an active, infectious lesion to enter the body through mucous membranes or compromised skin. Transmission occurs only if one person has an open sore on their lips, inside their mouth, or throat, and the kiss involves direct contact with that lesion.
These infectious sores are typically manifestations of primary or secondary stage syphilis. In the primary stage, the lesion is called a chancre, which is usually a firm, round, and painless ulcer. Secondary syphilis can involve flat, whitish, wart-like lesions, known as mucous patches, which are highly infectious and may appear in the mouth. Both chancres and mucous patches contain a high concentration of the bacteria, facilitating transmission.
The risk depends on the type of physical contact and the presence of these lesions. A casual kiss on the cheek or closed-mouth kissing without active oral sores carries virtually no risk. Deep or intimate kissing that involves contact with an active, moist lesion can allow the bacteria to spread.
Primary Modes of Syphilis Transmission
While oral transmission through kissing is possible, most syphilis cases are acquired through other routes. Syphilis is primarily transmitted through direct contact with an infectious sore during vaginal, anal, or oral sexual activity. The bacteria easily pass through the thin lining of the mucous membranes in the mouth, genitals, or rectum.
The probability of transmission is high during the primary and secondary stages when infectious lesions are present. Exposure to a partner with primary or secondary syphilis carries a significant risk of infection. Syphilis can also be transmitted vertically from a pregnant person to their baby during gestation, known as congenital syphilis. This vertical transmission poses a serious threat, highlighting the importance of routine prenatal screening.
Recognizing Symptoms and Testing
Recognizing the signs of syphilis is necessary because the infection can be subtle or mistaken for other conditions. The first sign, the chancre, typically appears between 10 and 90 days after exposure. Because the chancre is usually painless, it can be easily missed, particularly if located inside the mouth or rectum.
If the infection progresses without treatment, the secondary stage begins. This stage is characterized by a non-itchy rash that may appear anywhere on the body, frequently including the palms and soles. Other secondary symptoms include fever, swollen lymph nodes, and mucous patches in the mouth. These symptoms can resolve, leading to the latent stage where the person has no visible symptoms, but the infection remains.
Anyone who suspects exposure or notices an unexplained sore should seek medical attention immediately. Diagnosis is performed using blood tests, which look for antibodies against the T. pallidum bacteria. Syphilis is curable, and the preferred treatment for early-stage infection is a single injection of long-acting Penicillin G.