Chapter 50 Sexually Transmitted Infections: Herpes
INTRODUCTION
Description: Infection by the herpes simplex virus (HSV) results in recurrent symptoms that range from uncomfortable to disabling, and there is a special risk to the neonate when herpes infection occurs during pregnancy.
Prevalence: Forty-five to 50 million recurrent cases; 1 million new cases per year; one in four women have been infected.
ETIOLOGY AND PATHOGENESIS
Causes: Roughly 80% of genital herpes infections are caused by HSV type 2, with the remaining 20% caused by the HSV type 1 virus. (Up to 50% of first-episode cases of genital herpes are caused by HSV-1.) Exposure to type 1 virus often happens in childhood and causes oral “cold sores.” Previous infection with type 1 virus appears to provide some immunity to type 2 infections. The incubation period from infection to symptoms is generally approximately 6 days (range 3 to 9), with first episodes lasting from 10 to 12 days. The majority of patients with symptomatic, first-episode genital HSV-2 infection subsequently have recurrent episodes; recurrences are less frequent after initial genital HSV-1 infection.
Risk Factors: Roughly 75% of sexual partners of infected individuals contract the disease if intercourse occurs during viral shedding. Patients are infectious during the period from first prodrome through crusting of the lesions. Viral shedding may also occur asymptomatically. (Persons unaware that they have the infection or who are asymptomatic when transmission occurs transmit the majority of genital herpes infections.) Nonsexual transmission has not been documented.
CLINICAL CHARACTERISTICS
Signs and Symptoms
• Prodromal phase—mild paresthesia and burning (beginning approximately 2 to 5 days after infection)
• Progresses to very painful vesicular and ulcerated lesions, 3 to 7 days after exposure (may prompt hospitalization in up to 10% of patients)
• Dysuria caused by vulvar lesions, urethral and bladder involvement, or autonomic dysfunction (may lead to urinary retention)
DIAGNOSTIC APPROACH
Workup and Evaluation
Laboratory: Viral cultures (including type-specific serologic tests) of material taken by swab from the lesions (95% sensitivity). Smears of vesicular material may also be stained with Wright’s stain to visualize giant multinucleated cells with characteristic eosinophilic intranuclear inclusions.
Special Tests: Scrapings from the base of vesicles may be stained using immunofluorescence techniques to detect the presence of viral particles.
