Condyloma acuminata (anogenital warts)

Human papillomavirus is a nonenveloped DNA virus with low-risk types (6, 11) that cause warts and high-risk types (16, 18, and others) that drive cervical, anal, vulvar, penile, and oropharyngeal cancer, prevented by 9-valent vaccination and managed by type-specific screening rather than treatment of the virus itself.

Syphilis is a sexually transmitted infection with the spirochete Treponema pallidum that progresses through painless chancre (primary), disseminated rash and condyloma lata (secondary), latent, and tertiary stages including neurosyphilis, diagnosed by paired nontreponemal and treponemal serology and treated with a single dose of intramuscular benzathine penicillin G for early disease.

Herpes simplex virus type 1 or 2 establishes lifelong latency in sensory ganglia after mucocutaneous infection, causing painful vesicular-to-ulcerative outbreaks of the mouth or genitals with intermittent asymptomatic shedding; diagnosis is by NAAT of an ulcer swab and treatment is oral nucleoside analogues, escalating to intravenous acyclovir for encephalitis, severe mucocutaneous disease, or disseminated infection in immunosuppressed hosts.

Infectious genital ulcers are caused chiefly by herpes simplex virus and syphilis in the United States, with chancroid, lymphogranuloma venereum, and granuloma inguinale as less common causes, distinguished by ulcer pain, number, and associated lymphadenopathy, and worked up with an ordered panel of HSV NAAT, syphilis serology or darkfield, and targeted testing since a substantial minority of ulcers have no identified cause and empiric therapy is often required.

Trichomonas vaginalis is a flagellated protozoan sexually transmitted infection that presents with malodorous frothy yellow-green discharge and a strawberry cervix but is frequently asymptomatic, especially in men. Diagnosis rests on nucleic acid amplification testing of vaginal secretions, and treatment is a single 2 g oral dose of metronidazole or tinidazole with partner treatment and retesting in 3 months for high reinfection rates.

Chlamydia trachomatis is the most commonly reported bacterial sexually transmitted infection in the United States, frequently asymptomatic, and diagnosed by nucleic acid amplification testing of urine or genital/rectal/oropharyngeal swabs. Uncomplicated genital infection is treated with a single dose of azithromycin or a course of doxycycline, complications include pelvic inflammatory disease and epididymitis, and LGV serovars require a 21-day course and are an increasing cause of proctitis.

Lice (pediculosis) is infestation of the scalp, body, or pubic region with human lice (Pediculus humanus capitis, corporis, or Pthirus pubis), diagnosed by finding a live louse or a viable nit close to the hair shaft, and treated with topical permethrin, malathion, or oral ivermectin plus environmental measures; body lice additionally vector epidemic typhus, trench fever, and relapsing fever.

Scabies is an intensely pruritic skin infestation with the mite Sarcoptes scabiei, transmitted by close skin-to-skin contact and classically involving the finger web spaces, wrists, axillae, and genitals while sparing the face and scalp in adults. Diagnosis is clinical, confirmed by mineral oil microscopy when needed, and treatment is topical permethrin or oral ivermectin with simultaneous treatment of contacts.