Does Herpes Accelerate HIV Infection?Some researchers are beginning to suspect that when patients are infected with both viruses, the combination puts HIV on the fast track.
By Leslie Laurence
Nearly 20% of the U.S. population over age 12 is infected with the virus that causes genital herpes. While antiviral drugs can offer them relief from the periodic outbreaks of painful sores, which characterize the sexually transmitted disease, there is no cure for herpes, or even a national effort to contain its spread. As a result, in the United States the prevalence of genital herpes (or HSV-2) has jumped 30% since the late 1970s, according to the Centers for Disease Control and Prevention. Currently, an estimated 45 million Americans are thought to be infected. This high and growing number is especially worrisome to researchers investigating a possible synergy between HSV-2 and HIV/AIDS, a link first identified by the CDC in 1988 and supported throughout the 1990s by studies in the United States and abroad. Says Dr. Timothy Schacker, associate director of the Division of Infectious Diseases at the University of Minnesota, who has been studying the herpes-HIV link for more than a decade, "Early in the epidemic, persistent herpes was one of the first signs of HIV infection. Today it's the most common STD among people with HIV and symptom outbreaks are two to four times more frequent (in this population)." In addition, says Schacker, a person with herpes is more likely than someone without it to acquire HIV from unprotected sex with an infected partner. "There are accumulating data to suggest a significant biological interaction between (herpes and HIV) that results in more efficient sexual transmission of HIV and an increased rate of HIV replication," he writes in the 2001 issue of the journal Herpes. The way in which herpes increases HIV transmission is still unclear. Researchers theorize that the lesions provide an easy port of entry for the virus. While a report by the Institute of Medicine in the mid-1990s pointed out that STDs that cause genital ulcers, such as syphilis, may also increase vulnerability to HIV, public health experts say herpes is the most serious threat because of the exceptionally large number of people infected and because of its suspected ability to interact with HIV at the cellular level. Studies by Schacker and colleagues at the University of Washington in Seattle in the early 1990s showed that the presence of herpes seems to accelerate development of AIDS. "If you were HIV-infected and had herpes, your herpes would recur (far) more often than if you were not HIV-infected," explains Schacker. "So you have an opportunistic infection that reactivates more frequently than almost any other (AIDS-related) infection, and the insidious thing is that it doesn't cause major disease. But when your herpes reactivates, your HIV replicates with greater efficiency and you have a faster progression of your HIV." Researchers have yet to prove their underlying thesis that HIV and HSV-2 are intrinsically linked in some way other than both being linked to unprotected sexual contact. However, if their suspicions are correct that HSV-2 is highly implicated in both the transmission and progression of HIV/AIDS, the effect is potentially catastrophic. The CDC estimates that barely 20% of herpes cases are currently identified. Unlike gonorrhea, syphilis and chlamydia, which are legally required to be reported to the CDC and to have efforts made to find and treat patients and their infected partners, there is no national outreach on herpes, not even routine screening at public health clinics. Without symptoms, patients are unlikely to seek screening on their own, and recent studies suggest that some 80% of infections are transmitted via cells shed during asymptomatic periods. Dr. Robert E. Johnson of the CDC's Division of STD Prevention admits that the agency needs to do better. "Tests and therapies are now available, but a system to deal with herpes infection is not in place," he acknowledges. Dr. Lawrence Corey, a professor in the Division of Allergy and Infectious Diseases at the University of Washington, says physicians should do more. "At the very least, we should disclose to our patients that highly effective tests for herpes are now available. If we do not offer such service, we need to ask ourselves whether we will be comfortable explaining to our patients that we do not test for one of the most common STDs in the world." However, widespread testing is itself a topic of considerable debate. Some researchers worry about the psychological impact on patients who get false-positive results. And they wonder how to counsel people who accurately learn they have an incurable viral disease that may increase their risk of HIV infection. The CDC has recently launched several studies to help clarify these and other issues related to testing for herpes. In the end, however, identifying and counseling herpes carriers may do little to contain the disease. While treating herpes carriers with antiviral drugs, such as Valtrex, Famvir and Zovirax, can help reduce symptoms and viral shedding between outbreaks (by 94% in women, according to a study by Dr. Anna Wald of the University of Washington's Virology Research Clinic), it is unknown whether treatment helps limit the rate of transmission. (Investigations to determine the answer are under discussion.) True, says Schacker, "We haven't done the groundwork to show that suppress(ing) herpes prevents the acquisition and transmission of HIV but I think, frankly, we don't have the time to do that kind of study. Epidemiological data are suggestive enough and given that the worldwide epidemic is decimating entire populations, I think it's time to be a little bolder in looking at things that might stop the spread of HIV." Unfortunately, a recent try at a herpes vaccine by the pharmaceutical manufacturer Chiron failed in clinical trials and another vaccine by then-named GlaxoWellcome, which proved partially protective in women, is nowhere near market-ready. At the moment, the only preventive method, other than abstinence, is condoms. Consistent and correct condom use can reduce the risk of transmission of genital herpes, but only when the infected areas are covered and protected by the condom. Indeed, the first randomized double-blind controlled study of genital herpes transmission from men to women found that condoms offered significant protection for women, according to Wald, who headed the research team. Without an effective management strategy to combat the spread of herpes, the best hope for avoiding a calamity, if the virus is indeed the threat many researchers fear, is a public health campaign letting Americans know about the risks of infection. Dr. King Holmes, a University of Washington STD researcher, thinks a warning is long overdue: "The herpes and HIV story is to the point it's almost screaming now."
Leslie Laurence is a National Magazine Award-winning journalist specializing in women's health and health policy. Her work has appeared in Glamour, Town & Country, New York, Redbook and many other magazines.
This report is the ninth in kaisernetwork.org's series on emerging and underreported issues in HIV and Reproductive Health, which is available online. This is part of the KHN Morning Briefing, a summary of health policy coverage from major news organizations. Sign up for an email subscription.