Syphilis is a bacterial infection caused by the organism Treponema pallidum. While often associated with genital lesions, the infection can readily manifest in the mouth and throat, particularly following oral sexual exposure. The presence of these oral lesions can be an early indicator of the disease, which, if left untreated, progresses through distinct stages. Understanding the specific appearance of these signs is important for early identification, as the disease is preventable and curable with modern medical intervention.
Oral Manifestations of Primary and Secondary Syphilis
The first noticeable sign of syphilis in the mouth occurs during the primary stage as a lesion known as a chancre. This chancre develops at the site where the bacteria first entered the body, frequently on the lips, tongue, or tonsils. The lesion is a round, firm, and often painless ulceration, making it easy to overlook.
The chancre’s lack of pain is a distinguishing feature that often prevents seeking prompt medical attention. Although it heals spontaneously within three to six weeks, the bacteria remain active in the body, and the chancre is commonly accompanied by swollen lymph nodes in the neck region.
When the infection progresses to the secondary stage, about ten weeks after the initial infection, the most common oral manifestation is the formation of “mucous patches.” These patches present as slightly raised, grayish-white lesions surrounded by a reddish border.
Mucous patches are highly infectious and often appear on the inner cheek, the soft palate, or the tongue. These lesions are usually multiple, unlike the singular chancre. Secondary syphilis may also manifest as maculopapular lesions or split papules at the corners of the lips.
Transmission Routes and Risk Factors
Syphilis is primarily transmitted through direct contact with an active infectious lesion, such as a chancre or mucous patch, during sexual activity. The bacterium enters the body through minor cuts, abrasions, or the moist mucous membranes of the mouth, genitals, or anus. Transmission occurs during oral, vaginal, or anal sex when one partner has an active sore.
Transmission is particularly associated with oral sex, as the bacteria can enter the body through the lining of the lips or mouth, leading to an oral chancre at the point of entry. While less common, the infection can also be spread through close contact like kissing if an active oral lesion is present.
Risk factors include engaging in barrierless sexual activity involving contact with oral, genital, or anal mucosa. Having multiple sexual partners or having sexual contact with a person known to have syphilis increases the probability of exposure. Syphilis is not spread through casual, non-sexual contact, such as sharing eating utensils or using the same toilet seat.
Diagnosis and Medical Management
The diagnosis of syphilis is not solely based on the visual inspection of oral lesions, as these can be confused with other conditions. Initial suspicion based on the characteristic appearance of a chancre or mucous patch is followed by laboratory confirmation. If a lesion is present, a healthcare provider may perform a darkfield microscopic examination of fluid from the sore to directly observe the Treponema pallidum bacteria.
Confirmation relies on a combination of serologic blood tests, divided into nontreponemal and treponemal types. Nontreponemal tests, such as the Rapid Plasma Reagin (RPR) or Venereal Disease Research Laboratory (VDRL) tests, are used for initial screening and to monitor treatment response.
If a screening test is reactive, a treponemal test, like the Fluorescent Treponemal Antibody Absorption (FTA-ABS) or T. pallidum Particle Agglutination (TP-PA) test, is used for confirmation. Treponemal test results remain reactive for life, even after successful treatment.
Nontreponemal test titers decrease significantly following therapy; a fourfold decrease indicates an adequate response to treatment.
The standard medical management for early syphilis, including the primary and secondary stages, is the administration of antibiotics. Benzathine penicillin G is the preferred medication for all stages of the disease. For early syphilis, a single intramuscular injection of 2.4 million units is curative.
Patients with a documented penicillin allergy may be treated with alternative antibiotics, such as doxycycline or tetracycline. Following treatment, patients undergo follow-up testing with RPR or VDRL to ensure the infection has been eradicated. Individuals must abstain from sexual contact until their sores are completely healed and confirmed clear by a doctor.