A study published in the Journal of the American Medical Association gives new insight into the frequency and amount of viral shedding among those with asymptomatic genital herpes simplex virus-2 (HSV-2) and spotlights the risk of acquiring the virus from a partner with an unrecognized infection.

To evaluate differences in genital shedding (when the virus is present on the skin and in genital fluids) of HSV-2 between those with and without genital symptoms, researchers from the University of Washington in Seattle and the Westover Heights Clinic in Portland, OR, enrolled 498 subjects with positive blood tests for the virus. 410 subjects had symptomatic infections while 88 were without symptoms. For a minimum of 30 days, participants self-collected swabs of genital secretions that were tested for HSV DNA.

The symptomatic group shed virus more often (on 20.1% of days versus 10.2% of days with the asymptomatic group) and were three-fold more likely to have genital lesions detected. Shedding that occurred with genital lesions was of much longer duration than in those without symptoms.

Subclinical shedding (when virus is present in the absence of symptoms) also occurred more often in the symptomatic group, on 13.1% of days compared to 8.8% in those with no history of symptoms. However, the quantity of HSV-2 present during subclinical shedding was nearly the same in both groups, which the authors say points to the “high” risk of acquiring genital herpes even from a partner who may not have symptoms.

Writing in the commentary section of their article, the investigators say that their findings suggest clinicians should educate patients with positive HSV-2 blood tests about genital HSV transmission and symptoms (unrecognized infections decrease when patients are counseled about signs of herpes outbreaks). They also observe that methods proven to sharply reduce HSV transmission–condoms, daily use of antiviral medication, and disclosure to partners–are hampered because few HSV infections are recognized and routine blood testing for the virus is not widely done.

“If you don’t know you have herpes, you would understandably do nothing about it. And since the quantity of virus shed is about the same for symptomatic and asymptomatic people, the possibility for transmission is highly significant. In my mind, this simply adds more fuel to the argument that herpes testing is really important and underutilized.” says Terri Warren, one of the study’s authors.

Reference
E Tronstein, C Johnson, M Huang, S Selke, A Margaret, T Warren, L Corey, and A Wald. Genital Shedding of Herpes Simplex Virus Among Symptomatic and Asymptomatic Persons With HSV-2 Infection. Journal of the American Medical Association, 2011. 305(14):1441-1449.