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Acyclovir-Resistant Genital Herpes Found in Person with Healthy Immune System

Date: December 8, 1993
Source: National Institutes of Health (NIH)
Author: National Institute of Allergy and Infectious Diseases (NIAID)

Researchers at the National Institute of Allergy and Infectious Diseases (NIAID) report the first documented case of recurrent genital herpes in a person with a healthy immune system whose repeated outbreaks were not suppressed by oral acyclovir, the standard therapy for preventing recurrences.

The study revealed the patient's virus to be resistant to the drug, which suggests that acyclovir-resistant strains of the herpes virus may pose problems for healthy patients as well as for people with compromised immune systems.

The research report appears in the Dec. 9 issue of The New England Journal of Medicine. Genital herpes, a contagious viral infection caused by the herpes simplex virus (HSV), affects an estimated 30 million Americans. Each year, as many as 500,000 new cases may occur. Once a person is infected, the virus remains in the body and causes new outbreaks. While some people recognize only one or two recurrences in a lifetime, others may experience several outbreaks a year.

Acyclovir has safely and effectively suppressed frequent genital herpes recurrences in people with healthy immune systems for more than a decade," says Anthony S. Fauci, M.D., NIAID director. "This study, however, signals a limitation in the current treatment of this disease and underscores the need for new preventative and therapeutic strategies."

The possibility that resistance to acyclovir could occur in people with healthy immune systems has long been a concern," says Stephen E. Straus, M.D., chief of the Laboratory of Clinical Investigation (LCI) for NIAID and lead researcher on the study. "Viral resistance has been documented in animal models and already is a problem in people with compromised immune systems such as individuals with HIV infection."

While acyclovir-resistant genital herpes may be rare in people with healthy immune systems, the current study suggests that resistance to the drug may be emerging," Dr. Straus adds.

In an earlier NIAID study of long-term treatment to suppress outbreaks of genital herpes in people with healthy immune systems, investigators found evidence of acyclovir resistance, but could not link these findings to patients' outbreaks.

The current report describes a 24-year-old man who since November of 1990 has had frequent, symptomatic outbreaks of genital herpes despite increasing doses of oral acyclovir of up to 4.8 grams per day, which is six times the amount usually required to suppress recurrences. The patient's immune system has prevented the outbreaks from becoming severe or longlasting, the authors note.

Intravenous acyclovir or other antiviral therapies might suppress this patient's recurring disease, but the potential cost, side effects and probable temporary benefit that they would provide preclude consideration of these treatments," says Dr. Straus.

Study investigators acknowledge that this patient may have acquired an acyclovir-resistant virus through sexual contact with an HIV-infected partner known to be taking acyclovir. They suggest, however, that resistance also may have developed during the course of his therapy.

Dr. Straus' co-authors include Rhonda G. Kost, M.D., also of LCI, Edgar L. Hill, M.S., of the Division of Virology at Burroughs Wellcome Company, Research Triangle Park, N.C., and Michael Tigges, Ph.D., of Chiron Corporation, Emeryville, Calif.

NIAID, a component of the National Institutes of Health, supports research on AIDS, tuberculosis and other infectious diseases as well as allergies and immunologic diseases. NIH is an agency of the U.S. Public Health Service, part of the U.S. Department of Health and Human Services.