The seroprevalence of adults with herpes simplex virus type 2 (HSV-2) infection in the United States has been determined to be about 25 percent. However, only about 10 to 25 percent of these persons recall having symptoms of HSV infection. Consequently, it has been assumed that most persons with asymptomatic infections have less frequent or severe reactivation of this disease. Data that dispute this include the finding that after an educational session, asymptomatic persons often report that they did, indeed, have herpetic ulcerations. In addition, most persons infected with HSV-2 acquire the virus from a person who does not recall a history of HSV infection. Wald and colleagues performed a study to assess genital shedding of HSV-2 among a cohort of presumptively asymptomatic adults.

Persons enrolled were men and women who reported no history of genital herpes but were HSV-2 antibody–positive by serologic testing. The patients underwent a standard educational session on genital herpes that included photographs of lesions and discussion of symptoms. They were then asked to collect genital and perianal samples for viral culturing daily for three months. A symptom diary was maintained by each patient, and they were asked to come in for a clinic visit if they developed any lesions or symptoms.

Fifty-three HSV-2–seropositive adults without an apparent history of genital herpes enrolled in the study. Following the educational sessions, 62 percent of the women and 64 percent of the men reported having a genital ulcer, blisters or crusts during the follow-up period. The participants collected viral swabs for HSV culture for a median of 94 days, which produced more than 17,700 viral cultures. Positive HSV cultures were obtained on at least one occasion in 38 of the 53 persons. In 36 of these 38 persons, the virus was isolated on days in which there were no apparent genital lesions (asymptomatic shedding). Collectively, HSV was isolated in the absence of genital lesions on 3 percent of the total days. In nine patients for whom all cultures were negative, six had HSV DNA detected by polymerase-chain-reaction assay. The overall rate of HSV detection in persons without a history of clinical infection was 83 percent.

Among the comparison group of 90 persons who had a history of genital HSV, daily viral cultures were obtained. Positive results were obtained on 6.4 percent of all days tested, but in 36 percent of the cases, the participants had no apparent genital lesions. The overall rate of subclinical (asymptomatic) viral shedding was 2.7 percent. This was almost identical to the first cohort, who had initially reported not having a history of genital herpes.

The authors conclude from this study that a significant degree of asymptomatic shedding of HSV occurs among persons with this infection. Included are men in whom physicians have traditionally dismissed the notion of this occurring. The prior assumption has been that asymptomatic shedding occurred only in women who shed the virus from the cervix or vaginal mucosa. In addition, it is clear that patient counseling and education about HSV-2 allows most patients to recognize the typical lesions of HSV. Because most persons with HSV-2 infection are asymptomatic, episodic or chronic administration of oral antiviral therapy is not required. However, it is important to educate and counsel patients about the risk of HSV transmission to sexual partners.

editor's note: This study presents two key points for practicing physicians. First, patient education about HSV infection is effective if done properly. Second, the risk of transmission, even in the absence of symptoms, should be explained to patients. The larger question that now remains is the role of antiviral therapy, which has historically been used only in patients with frequent outbreaks, with the intent of decreasing symptoms and viral transmission. This study makes me further question the efficacy of limiting this therapy to patients with frequent symptomatic recurrences.—j.t.k.