All you need to know about Syphilis

ETIOLOGY: Syphilis is caused by T. pallidum.

INCIDENCE: Each year, there are 29,000 new cases of syphilis. This figure represents probably only 10% of actual cases.

CLINICAL FEATURES

1. Primary syphilis: After an average incubation period of approximately 3 weeks, a smooth, painless ulcer called a chancre appears at the site of primary inoculation. The chancre heals without treatment in approximately 3 to 6 weeks; at about the same time, a painless uni- or bilateral regional adenopathy develops.

2. Secondary syphilis represents disseminated disease and occurs in all patients with untreated primary infection. The lesions of secondary syphilis are papulosquamous lesions that occur over the entire trunk, extremities, penis, and buttocks. Fever and weight loss occur in 70% of patients.

3. Tertiary syphilis occurs at least 10 years after the primary infection in at least 30% to 35% of untreated patients. The two most important manifestations of tertiary syphilis are cardiovascular syphilis, causing thoracic aneurysms, and neurosyphilis, causing meningitis, stroke, seizures, dementia, general weakness, and posterior column dysfunction.

DIFFERENTIAL DIAGNOSES

— Chancroid

— HSV type 1 infection

— Lymphogranuloma venereum

— Tinea, sarcoid

— Lichen planus

— Seborrhea dermatitis

— Molluscum contagiosum

— Traumatic ulcer

— Furuncle

— Carcinoma

EVALUATION: The clinical diagnosis can be confirmed by darkfield microscopic examination or more commonly serologic testing.

THERAPY

1. The standard treatment for primary, secondary, and early tertiary syphilis is benzathine penicillin G (2.4 million U administered intramuscularly as a single dose).

2. For late tertiary syphilis or neurosyphilis, benzathine penicillin G (2.4 million U, three doses administered intramuscularly 1 week apart) is used. Doxycycline (100 mg orally twice daily for 14 days) can be given to patients who are allergic to penicillin.

DISPOSITION

1. Primary and secondary syphilis can be treated on an outpatient basis.

2. Patients with neurosyphilis or major cardiovascular manifestations require admission for intravenous therapy.