Herpes simplex virus (HSV) infection

Herpes zoster is reactivation of latent varicella-zoster virus from a sensory ganglion, producing a painful, dermatomal vesicular rash that does not cross the midline, most common in adults older than 60 years and in immunosuppressed hosts; diagnosis is clinical, confirmed by VZV PCR when needed, and antiviral therapy started within 72 hours of rash onset shortens the illness and reduces postherpetic neuralgia.

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.

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.

Pelvic inflammatory disease is an ascending polymicrobial infection of the upper female genital tract, most often caused by Neisseria gonorrhoeae, Chlamydia trachomatis, or Mycoplasma genitalium, diagnosed clinically on uterine, adnexal, or cervical motion tenderness. Most women are treated as outpatients with a single dose of ceftriaxone plus 14 days of doxycycline, while parenteral cefotetan or cefoxitin plus doxycycline, or clindamycin plus gentamicin, is reserved for hospitalized patients, with tubo-ovarian abscess and infertility among the major complications of delayed treatment.

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.

Acute HIV infection, also called the acute retroviral syndrome, is the symptomatic viremic phase in the days to weeks after HIV acquisition, presenting with fever, fatigue, myalgia, rash, and pharyngitis at a time when antibody testing may still be negative. Diagnosis requires an HIV RNA viral load, and antiretroviral therapy should begin as soon as the patient is ready, regardless of CD4 count.

Cytomegalovirus is a ubiquitous herpesvirus that is usually asymptomatic or causes a heterophile-negative mononucleosis-like illness in healthy hosts, but reactivates to cause retinitis, colitis, pneumonitis, or encephalitis in transplant recipients and patients with AIDS; treatment is systemic ganciclovir or valganciclovir, with foscarnet and cidofovir reserved for resistance or intolerance.

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.

Acute purulent infection of the meninges beyond the neonatal period, most often from Streptococcus pneumoniae or Neisseria meningitidis, diagnosed by CSF analysis after prompt lumbar puncture and treated with immediate empiric intravenous antibiotics plus adjunctive dexamethasone, since any delay in therapy worsens outcome and mortality remains near 25%.