by Liz Highleyman
23 April 2011
People without genital sores or other symptoms can still shed and transmit herpes simplex virus type 2 (HSV-2) during sex, according to a recent U.S. study.
Herpes simplex virus type 2 is the usual cause of genital herpes, while type 1 typically causes cold sores; both types, however, can infect either area.
HSV causes painful blisters on the skin and mucous membranes
and sometimes also flu-like symptoms. Between outbreaks it lies dormant in
nerve cells, but can be reactivated by triggered factors such as concurrent
infections, hormonal fluctuations, or exposure to sunlight.
As described in the
April 13, 2011, Journal of the American Medical Association, Anna
Wald from the University of Washington and colleagues evaluated the
virological and clinical course of genital virus shedding among people with
symptomatic and asymptomatic HSV-2 infection.
HSV-2 is among the most common sexually transmitted infections worldwide, with
global estimates of 536 million total people infected and 23.6 million new
cases each year, Wald explained at a JAMA media briefing at the
National Press Club in Washington, DC.
At any given time many people with
HSV-2 will not have lesions or other symptoms, and some individuals rarely or
never experience symptoms. A growing number of people are aware they have
genital herpes thanks to the availability of commercial HSV-2 antibody tests,
but screening is not widespread. In the U.S. an estimated 16% of adults are
HSV-2 seropositive, but only 10% to 25% of them have recognized genital
herpes. Furthermore, the natural history of HSV-2 infection in asymptomatic
seropositive individuals is not fully understood.
The present study included 498 immunocompetent HSV-2 seropositive people
enrolled in prospective studies of genital HSV shedding -- an indicator of
active viral replication -- at the University of Washington Virology Research
Clinic in Seattle and the Westover Heights Clinic in Portland between March
1992 and April 2008. Each participant collected swabs of genital secretions
daily for at least 30 days. The researchers then used quantitative real-time
polymerase chain reaction (PCR) assays to measure HSV-2 in samples.
Results
HSV-2 was detected on 4753 of 23,683 total days, or 20% of the time, among 410 people with symptomatic genital herpes.
HSV-2 was detected on 519 of 5070 total days, or about 10% of the time, among 88 individuals with consistently asymptomatic infection.
Genital HSV-2 was detected at least once in 342 of 410 people (83%) with symptomatic infection and in 60 of 88 people (68%) with asymptomatic infection during an average 57 days of follow-up.
Subclinical shedding in the absence of symptoms was significantly more common among people with symptomatic HSV-2 infection compared with asymptomatic infection (2708 of 20,735 days or 13% vs 434 of 4929 days or 9%).
However the amount of HSV-2 detected during subclinical shedding episodes was similar in the symptomatic and asymptomatic groups (median 4.3 vs 4.2 log copies, respectively).
People with symptomatic infection had more frequent genital HSV-2 shedding episodes than people with asymptomatic infection (median 17.9 vs 12.5 episodes per year).
Days with evident lesions accounted for 2045 of 4753 days with genital virus shedding (43%) among people with symptomatic genital HSV-2 infection compared with 85 of 519 days (16%) among people with asymptomatic infection.
Based on these findings, the study authors concluded, "Persons with
asymptomatic HSV-2 infection shed virus in the genital tract less frequently
than persons with symptomatic infection, but much of the difference is
attributable to less frequent genital lesions because lesions are accompanied
by frequent viral shedding."
Though less common, HSV-2 shedding did occur among asymptomatic people without
evident genital lesions, indicating that such individuals may transmit the
virus between outbreaks of symptoms.
"Our findings suggest that 'best practices' 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 recommended at the press
conference. "The issue of infectivity is both a patient management and a
public health concern."
Measures including condom use and daily valacyclovir (Valtrex) treatment can
help decrease HSV-2 transmission to sex partners, but risk reduction is not
complete and many people do not take advantage of such measures because they
do not realize they are infected. It is a common misconception that HSV-2 can
only be transmitted when lesions are present, indicating the need for better
public health education in this area.
Investigator affiliations; Departments of Medicine, Laboratory Medicine, and Epidemiology, University of Washington, Seattle, WA; Vaccine and Infectious Disease Institute and Program in Biostatistics, Fred Hutchinson Cancer Research Center, Seattle, WA; Westover Heights Clinic, Portland, OR.
4/23/11
Reference
E Tronstein, C Johnston, ML Huang, et al. Genital shedding of herpes
simplex virus among symptomatic and asymptomatic persons with HSV-2 infection.
Journal of the American Medical Association 305(14):1441-1449 (abstract).
April 13, 2011.
Other Source
JAMA. Persons With Herpes Simplex Virus Type 2, But Without
Symptoms, Still Shed Virus. Media advisory for April 12, 2011.
http://hivandhepatitis.com/other-stds/herpes/2914-genital-herpes-virus-can-spread-despite-lack-of-symptoms