Risk for transmission comparable among symptomatic, asymptomatic HSV-2

Tronstein E. JAMA. 2011;305:1441-1449.

The risk for transmission was increased among patients with asymptomatic herpes simplex virus and comparable to symptomatic patients. This may be largely due to the unrecognizable amount of shedding days in these patients, according to Anna Wald, MD, MPH.

Wald, professor in the department of medicine, epidemiology and laboratory medicine at the University of Washington, and colleagues found that genital shedding was increased twofold and the risk for genital lesions almost threefold in patients with symptomatic herpes simplex virus-2 (HSV-2). Yet, the amount of virus shed subclinically was similar between symptomatic and asymptomatic patients — genital shedding occurred during 10% of days for both groups, of which 84% was subclinical.

“The finding that the quantity of virus shed during subclinical episodes is comparable in symptomatic and asymptomatic persons underscores the epidemiologic observations that the risk for HSV-2 transmission is high from persons with unrecognized HSV-2 infection,” Wald said during a Journal of the American Medical Association media briefing.

In the prospective study, researchers analyzed self-collected swabs of genital secretions from 498 patients for at least 30 days from 1992 to 2008 (patient mean age was 40.7 years; 56.8% were female). Viral shedding rates were measured with quantitative real-time fluorescence polymerase chain reaction. The number of days with positive swab results was then divided by the total number of days with swabs collected for each person.

Symptomatic genital herpes infection was reported in 82.3% of patients, whereas 17.7% of patients were asymptomatic at time of serological documentation of HSV-2 infection. Lesion-days accounted for 43% of total days in symptomatic patients compared with 16.4% of days in asymptomatic patients (P<.001).

Moreover, HSV-2 infection was identified for 10.2% of days among asymptomatic patients (95% CI, 7.7-13.6) vs. 20.1% of days among symptomatic patients (95% CI, 18.3-22). Although subclinical shedding rates were higher among symptomatic patients (13.1% vs. 8.8%), HSV detected during subclinical shedding were similar between the two groups (4.3 vs. 4.2, respectively; P=.27).

“Management of HSV-2 infected persons who learn that they are infected from serologic testing should include anticipatory guidance with regard to genital symptoms, as well as counseling about the potential for transmission,” Wald said. “Few people are aware of their genital HSV-2 infection, and routine serologic testing, although available commercially, is recommended only in limited settings.”

Disclosure: Dr. Wald received research support from the National Institutes of Health and GlaxoSmithKline; and is a consultant for AiCuris.

An estimated 50 million people in the United States are infected with HSV-2, and most of these HSV-2 infections are asymptomatic or unrecognized. However, as highlighted by this study, viral shedding and transmission to sex partners often occurs in the absence of symptoms or a noticeable lesion. This demonstrates the importance of counseling HSV-2 infected persons about the transmission risk associated with subclinical viral shedding. Although routine HSV-2 screening in the general population is not indicated, type-specific HSV serologic tests can be useful for diagnosing HSV-2 infections in several scenarios, including recurrent genital symptoms or atypical symptoms with negative cultures. Serologic testing should also be considered for people seeking a full STD evaluation, especially those with multiple sex partners, people with HIV infection, and men who have sex with men. CDC encourages providers to share with all of their sexually active patients the individual measures that can reduce HSV-2 acquisition, including minimizing the number of sex partners and using condoms consistently and correctly.

– Kevin Fenton, MD

Infectious Disease News Editorial Board member

Disclosure: Dr. Fenton reports no relevant financial disclosures.

This study helped to characterize the type and frequency of shedding in those individuals with truly asymptomatic infection. Shedding rates were two times higher for those with symptomatic genital HSV-2 and the risk for lesion about three times higher than those with asymptomatic disease. Most of the differences in total shedding rates were attributable to lesional episodes. Still, asymptomatic shedding was common and frequent in the asymptomatic group. The amount of virus shed subclinically was similar for both groups. What we can clearly say is not having outbreaks does not reduce your risk for transmitting infection to partners and the high frequency of shedding for those with or without clinical outbreaks, provides a biologic explanation for the high prevalence rate for genital HSV-2 infection. Hopefully, this study will get clinicians to understand that virtually all individuals with genital HSV-2 infection will shed virus and do so asymptomatically whether or not that individual provides a history of genital herpes disease, whether they were diagnosed by serologic screening, whether they are male or female, or they are years away from their initial diagnosis. This study underscores the need for a broader offering of serologic screening for HSV-2 infection for sexually active adults and highlights the need for a national strategy for control and management of HSV-2 in the US.

– Peter Leone, MD

University of North Carolina School of Medicine

Disclosure: Dr. Leone reports no relevant financial disclosures.

Follow InfectiousDiseaseNews.com on Twitter.