Identifying asymptomatic people with genital herpes infection through targeted screening of high-risk groups may prevent disease transmission. However, widespread screening of pregnant women is unlikely to reduce the occurrence of herpes in newborns, according to an article in the January 1 issue of Clinical Infectious Diseases, now available online.
Herpes simplex virus type 2 (HSV-2) infects more than one-fifth of the United States population, but about 90 percent of those people are unaware that they are infected, since most do not experience any symptoms. In this case, though, ignorance is not bliss--a person infected with HSV-2 can unknowingly pass the virus to sexual partners and has a doubled risk of contracting HIV from unprotected sex.
Screening for HSV-2 has become possible with the advent of a blood test that can detect antibodies to the virus. A committee of sexually transmitted disease (STD) experts in California considered the potential risks and benefits of HSV-2 screening in four groups of asymptomatic people: people at high risk for STDs, HIV-positive people, people whose partners have HSV-2 and pregnant women. The authors found that the first three groups are likely to benefit from screening for HSV-2. Infected individuals could be counseled regarding condom use and advised about changing their behavior to reduce the risk of acquiring HIV or transmitting genital herpes.
However, the article concluded that pregnant women who are not HIV-infected and whose partners do not have genital herpes should generally not be screened for HSV-2. The authors rejected universal screening of pregnant women for HSV-2 because there was little evidence that the test results would lead to safe and effective prevention of disease transmission to newborns. Most women who have had genital herpes for three months or longer have antibodies that should protect their babies from infection. Women who have just contracted HSV-2 are at highest risk of passing genital herpes to newborns, but they haven't developed antibodies yet, so the screening test doesn't show infection. If a pregnant woman knows that her partner has genital herpes, she can lower her risk of contracting the disease and transmitting it to her baby by avoiding sex or by using condoms during the third trimester.
"It's about using these tests with caution and with counseling," said Sarah Guerry, MD, currently with the County of Los Angeles Department of Health Services. Because there is no treatment for asymptomatic HSV-2, she suggested that doctors "need to do good pre-counseling before using these tests and be prepared to counsel afterwards."
"Screening should be done cautiously in specific populations," said Dr. Guerry. "What you're testing for is a chronic, incurable STD ... You've got to make sure screening is doing more good than harm," Dr. Guerry said.