UW News

March 23, 2000

People unknowingly spread epidemic of sexually transmitted disease

A study from the University of Washington published in the March 23 New England Journal of Medicine warns that an epidemic of sexually transmitted disease is likely to continue unless people learn whether they have genital herpes.

An estimated one out of four Americans already has genital herpes caused by herpes simplex virus type 2 (HSV-2), but most of them don’t know it. The study overturns a myth and reveals that people who appear asymptomatic — who likely don’t know they have the disease — are just as likely to be infectious as people who know their diagnosis.

Because the disease can lurk unseen or show only subtle symptoms, it is estimated that only one in five infected people knows that he or she is infected. Someone who does not know can easily transmit the disease to someone else without knowing. In turn, that person could go on to develop painful symptoms, or possibly infect a newborn during birth.

“Previously, many people thought that asymptomatic persons were less likely to shed HSV in the genital area than those with chronic symptoms. That’s just not true. Even asymptomatic people shed a lot,” says Dr. Anna Wald. She is director of the UW Virology Research Clinic and an assistant professor of allergy and infectious diseases in the UW School of Medicine and of epidemiology in the School of Public Health and Community Medicine.

The lesson is that doctors need to start paying attention to people who do not think they have the disease, but may have it. “At present, the medical and public health communities largely ignore persons who have asymptomatic HSV-2 infection because little information is available as to what is the benefit in identifying such persons,” Wald says. “In fact, most HSV-2 infections are acquired from a person with no history of genital herpes infection. In order to prevent the spread of HSV-2 to babies and to sexual partners, we will have to identify and control the infection in people who do not currently realize they have the disease.”

Herpes lesions may manifest themselves as blisters, ulcers or crusts on the genital or perianal area, and the buttocks. Genital herpes is a virus that attacks the body through tiny passages in the skin. It is transmitted by sex. HSV also can be spread through oral sex if the carrier has a herpes sore on the mouth or genitals.

After the initial infection, genital herpes lurks without symptoms in nerves at the base of the spinal cord. But when it travels along the nerves to the skin, it makes a painful appearance. Symptoms include tingling and burning, and blisters and ulcers in the genital area.

The disease has no cure, but it is not fatal. It can be suppressed with medication, such as acyclovir. Yet herpes is dangerous because herpes sores allow easier transmission of HIV. And genital herpes can have serious ramifications during pregnancy, because the baby can become infected.

In the study, scientists found 53 people who had tested positive for HSV-2 but who said they were unaware that they had the infection. The study also looked at 90 people who were aware that they had genital herpes. The study of genital secretions over three months found that HSV was being shed in 72 percent who were not aware that they had genital herpes.

The study also reveals that education can help people determine whether they have the disease. As part of the test, people who had tested positive on a blood test, but who had not realized they had the disease, were shown pictures of herpes sores and given explanations of how to recognize the condition. The study found that after three months, 87 percent of them reported they could now recognize the herpes symptoms. However, the outbreaks were less frequent and shorter than among those people who had diagnosed genital herpes.

So far, it’s been difficult to diagnose genital herpes, or HSV-2, because older blood tests confuse it with herpes type 1. But new blood tests are making easier to diagnose people with genital herpes, Wald says. Most people with HSV-2 have mild symptoms, which are easily confused with other conditions. Testing and counseling may be a method to help reduce transmission.

The study addresses the myth that men are less likely to have asymptomatic shedding, because their sexual anatomy includes more skin than mucosa. However, the rate of shedding by asymptomatic women and men was about the same for both genders.

Other authors involved in the study are Dr. Lawrence Corey, a UW professor of laboratory medicine and allergy and infectious disease, and a member of the clinical research division of Fred Hutchinson Cancer Research Center; Dr. Rhoda Ashley, professor of laboratory medicine; Dr. John Krieger, professor of urology; Judith Zeh, UW research associate professor in statistics; Alexander J. Ryncarz and Stacey Selke of the Department of Laboratory Medicine; and Terri Warren of the Westover Heights Clinic in Portland.

The UW Virology Research Clinic has several research programs related to the disease. They are leading a team that will study how health care professionals can help educate people about the disease and prevent it. Also, Wald and colleagues are testing a new vaccine that might improve conditions for people who have genital herpes. Another vaccine is being tested in people who do not have herpes. And UW scientists are testing what kind of medicine might help prevent transmission of the disease from an infected person to an uninfected partner.

People interested in participating in studies relating to HSV-2 can call the Virology Research Clinic at (206) 720-4340.