Long-term treatment of genital herpes with the drug acyclovir does not reduce the rate of new HIV infections, researchers reported at the International AIDS Conference here last week.

They said the findings are surprising, because prior infection with herpes simplex virus type 2 (HSV-2), the virus that causes genital herpes, has been reported to increase the risk of HIV many fold.

In a randomized multicenter trial, Dr. C. Celum of the University of Washington, Seattle, and colleagues evaluated the effects of acyclovir in 1,814 gay men who have sex with men from the United States and Peru, and in 1,358 women from Zimbabwe, Zambia and South Africa. All were infected with HSV-2 but not with HIV, the virus that causes AIDS.

Subjects took acyclovir or placebo pills twice daily and were followed monthly for up to 18 months.

While the incidence of genital ulcers was significantly lower in the acyclovir group, the incidence of HIV infection was the same in both the groups, the researchers observed.

They suggest that infection with the genital herpes virus may be a risk marker, not a risk factor, for HIV infection. Alternatively, perhaps, the interventions against HSV were not potent enough.

By C. Vidya Shankar, MD

MEXICO CITY (Reuters Health)