Syphilis is caused by the spirochete Treponema pallidum. It is solely a human pathogen. Transmission is primarily from sexual activity and occurs via penetration through mucous membranes and abrasions on epithelial surfaces. It can also be acquired via placental transmission and blood transfusions.31 The average incubation time is about 3 weeks but ranges from 10 to 90 days. It is more common in men, particularly men who have sex with other men. In 2011, 72% of primary and secondary syphilis occurred among men who have sex with men.32 Tertiary syphilis develops in 8% to 40% of untreated patients over several decades following primary infection.3
Syphilis continues to cause considerable morbidity and facilitates HIV transmission.33 The primary lesion of syphilis is the chancre developing within 3 weeks after contact. Symptoms of syphilis in adults can be divided into stages.34 Chancres are usually round, painless, and firm ulcerations. These are seen primarily on the genitals, anus, or lips of affected individuals. Since they are painless they usually go unrecognized especially if they occur in the anus or vagina. During this primary stage, spirochetes can be isolated from the surface of the ulcer. Whether treated or not, healing of the chancre lesion occurs in 3 to 12 weeks. Commonly nontender bilateral inguinal/regional lymphadenopathy may be present.10 Figure 88-4 demonstrates a primary syphilitic penile chancre. Latent syphilis, defined as those patients without clinical manifestations, is detected by serological testing.3
Primary syphilitic penile chancre. (Reproduced with permission from Centers for Disease Control Public Health Image Library.)
Secondary syphilis occurs anywhere from the time of the primary lesion healing to months after its resolution. It is characterized by the development of a rash and lymphadenopathy (Fig. 88-5). The rash is usually generalized, nonpruritic, maculopapular beginning on the trunk/arms and spreading to the palms and soles.35 Mucous membrane involvement includes oral lesions and condyloma lata (cauliflower-like growths that are infectious) usually occurring in the anogenital region (Fig. 88-6). Patchy alopecia may develop. Systemic symptoms of fever, malaise, anorexia, arthralgias, hepatitis, and generalized lymphadenopathy are described.32 As with primary syphilis, this stage will resolve with or without treatment. Without appropriate treatment, the infection will progress to the latent and possibly late stages of the disease.
Exanthem of secondary syphilis. (Reproduced with permission from Centers for Disease Control Public Health Image Library.)
Vaginal ulcer from secondary syphilis. (Reproduced with permission from Centers for Disease Control Public Health Image Library.)
The latent, or asymptomatic phase, may last from a few years to as many as 25 years. Affected patients may recall symptoms of primary and secondary syphilis. They are asymptomatic during the latent phase, and the disease is detected only by serologic tests.
Latent syphilis is divided into early and late. The early latent period is the first year after the resolution of primary or secondary syphilis. During this time, individuals are asymptomatic but still considered infectious. Late latency syphilis is generally not considered infectious; however, women in this stage can spread the disease in utero leading to congenital syphilis. These individuals are only identifiable by serologic testing. If untreated, patients may progress to the more destructive tertiary phase of syphilis.
Tertiary (late) syphilis is slowly progressive and may affect any organ. It is thought that about 15% of untreated individuals will progress to this stage.32 The disease is generally not thought to be infectious at this stage. Tertiary syphilis can affect virtually any organ including the skin, lungs, cardiovascular, central nervous system, ocular, and musculoskeletal.31,32 When the nervous system is affected it is referred to as neurosyphilis. Clinical manifestations include headache, dementia, problems with coordination, altered behavior, and movement disorders.
Congenital syphilis is transmitted vertically, from a pregnant woman to her fetus. It is relatively rare with 377 cases reported in 2010.4 Infection results in a wide spectrum of disorders. Clinically, only the most severe cases are recognized at birth making prenatal screening imperative.
Early clinical findings usually become apparent by 3 months of age and include hepatomegaly, syphilitic rhinitis (snuffles), lymphadenopathy, and rash. Other symptoms may include fever, myocarditis, pneumonia, pseudoparalysis of Parrot (failure to move an extremity secondary to pain), ophthalmologic and gastrointestinal manifestations.36 Late congenital syphilis is characterized by facial features, interstitial keratitis, hearing loss, skeletal, dental (Hutchinson teeth), and cutaneous abnormalities.37 Diagnosis is usually made serologically with other options including dark-field microsopy and histopathologic examination.
Diagnosis in the first or second stage is by dark-field and direct fluorescent antibody (DFA) of the treponemes from the chancre of condyloma lata or oral lesions. This technology is generally not available so it is rarely performed. Serologic tests include nontreponemal VDRL or RPR and treponemal FTA-ABS and treponemal enzyme and chemiluminescence immunoassays (EIA/CIA). Sensitivity is 78% for RPR and 86% for VDRL in primary syphilis and 100% in secondary syphilis.4 The recommended testing for syphilis is screening tests with “nontreponemal” assay (VDRL, RPR) and confirmation with the treponemal test.38 These tests become negative 1 year after treatment. The treponemal tests stay positive for life and do not correlate with disease activity.4
Penicillin G, administered parenterally, is the preferred drug for treatment of all stages of syphilis.12 Benzathine penicillin G 2.4 million units IM as a single dose remains the treatment of choice for the primary and secondary uncomplicated infections. Patients with latent or tertiary syphilis are also treated with Penicillin G although the duration and frequency is different. Doxycycline, tetracycline, and ceftriaxone remain alternatives (Table 88-1). Children with syphilis should have CSF examination to detect asymptomatic neurosyphilis. Treatment for children is benzathine penicillin G 50,000 units/kg IM up to the adult dose as a single injection (Table 88-1).12 Again, for latent and tertiary syphilis additional doses are required.12