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Even Without Symptoms, Persons with Herpes Spread the Virus

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June 23, 2011

Persons who have tested positive for herpes simplex virus type 2 (HSV-2) shed the virus even when they don't have symptoms, according to new research. Writing in the April 13 issue of the Journal of the American Medical Association, researchers led by Anna Wald, MD, MPH of the University of Washington and the Fred Hutchinson Cancer Research Center suggest a high risk of transmission from persons with unrecognized HSV-2 infection.

Researchers compared the rates and patterns of genital HSV shedding in 498 adults who had tested positive for HSV-2. "Viral shedding" refers to presence of virus that is actively replicating and can be transmitted to another person. Of the subjects, 410 had symptoms and 88 had no symptoms. The 88 asymptomatic individuals were unaware that they had the disease and learned that they were infected after serology tests, which detect antibodies to the virus in the blood, were positive.

Each participant collected swabs of genital secretions for at least 30 days. The researchers used polymerase chain reaction (PCR), a way of testing for viral genetic material (DNA), to determine the rate of viral shedding. The researchers compared the amount of virus present in fluid from asymptomatic people to the amount of virus in fluids from those with active signs and symptoms.

The scientists found that asymptomatic patients shed the virus less frequently, one day out of every 10, than symptomatic patients, who shed the virus one day out of every 5. However, the amount of virus in secretions from both groups was comparable, the researchers say. Genital herpes is a sexually transmitted disease with symptoms that aren't always recognized. The classic symptom of genital herpes is groups of small fluid-filled blisters that break, form painful sores, and then crust and heal over several days. But some people get only a rash or small pimple-like bumps on the skin.

Testing is an important part of curtailing the spread of genital herpes. Generally, doctors will order a culture that can detect the virus in a sample taken from a lesion. DNA testing is usually done if the culture is negative but the doctor still suspects genital herpes. DNA testing can both detect the virus and identify the type.

Currently, herpes screening recommendations from different health organizations vary somewhat. The United States Preventive Services Task Force, the Centers for Disease Control and Prevention (CDC), as well as the American Academy of Family Physicians recommend against screening for HSV-2 in asymptomatic individuals. The American College of Obstetricians and Gynecologists recommends screening asymptomatic persons if they have a sexual partner who has herpes.

Even if a person does not have any symptoms of herpes, he or she can still infect sex partners and should take precautions to avoid its spread, this study shows. The CDC recommends that people with herpes abstain from sexual activity with uninfected partners when lesions or other symptoms of herpes are present. Even when symptoms are not present, they should advise partners that they may become infected and use condoms to reduce the risk of spreading the disease.

The researchers are in agreement with the CDC and note practices that can reduce the risk of HSV-2 transmission to sexual partners by about half. These include condom use, daily anti-viral (valacyclovir) therapy, and disclosing HSV-2 status. "However, these approaches reach a small portion of the population and have not had an influence on HSV-2 seroprevalence in the last decade," write the researchers. "One of the reasons for such a limited effect is that few people are aware of their genital HSV-2 infection, and routine serologic testing, although available commercially, is recommended only in limited settings. We hope that these data will result in further discussions regarding control programs for HSV-2 in the United States."

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Tronstein, Elizabeth et al. Genital Shedding of Herpes Simplex Virus Among Symptomatic and Asymptomatic Persons With HSV-2 Infection. Journal of the American Medical Association. Available online at through Published April 13, 2011. Accessed May 23, 2011.

JAMA press release. Persons With Herpes Simplex Virus Type 2, But Without Symptoms, Still Shed Virus. Available online at through Released April 12, 2011. Accessed May 23, 2011.

U.S. Centers for Disease Control and Prevention. CDC Fact Sheet: Genital Herpes.  Available online at through Updated July 13, 2010. Accessed May 23, 2011.

(March 2005) United States Preventative Services Task Force. Screening for Genital Herpes, Summary of Recommendations. Available online at through Accessed May 2010.

Meyers D et al. USPSTF STI Screening Recommendations. Am Fam Physician. 2008 Mar 15;77(6):819-824. Available online at through Accessed May 2010.

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