Herpes Simplex Virus

Herpes simplex virus (HSV) is a double-stranded DNA virus that infects mucocutaneous epithelium and then establishes lifelong latency in sensory nerve ganglia. HSV-1 is traditionally associated with oral disease and HSV-2 with genital disease, but either type can infect either site. During an outbreak, viral replication damages epithelial cells and produces painful, grouped vesicles on an erythematous base. The vesicles break, leaving shallow ulcers that eventually crust and heal. After the initial infection, the virus travels along sensory nerve axons to the ganglion. It remains there rather than being eliminated, which explains why treatment controls outbreaks but does not cure the infection. Reactivation travels back along the sensory pathway to a related skin or mucosal site. Fever, local trauma, menstruation, stress, sunlight exposure, and immunosuppression can precipitate an episode, although many recurrences have no obvious trigger. Viral shedding may occur when the skin looks normal, so the absence of lesions does not eliminate transmission risk. A first recognized genital episode may involve extensive painful lesions, dysuria, fever, malaise, myalgia, or tender inguinal nodes. Recurrences are often shorter and more localized,...