Cape Town - A microbicide gel initially intended to offer protection against HIV has been found to be effective against herpes.
Herpes is one of the most common sexually transmitted diseases in South Africa.
In testing, the gel had initially been shown to provide at least some protection from HIV infection in women.
In the latest study, published in the New England Journal of Medicine, researchers from the Centre for the Aids Programme of Research in South Africa (Caprisa) showed that Tenofovir gel halved the risk of developing herpes simplex virus type 2 – a virus that is a leading cause of genital ulcers.
The microbicide gel, which contains Tenofovir – an anti-retroviral usually used for HIV treatment – made headlines and raised hopes in the HIV community a few years ago when initial studies found it reduced HIV infection in 39 percent of women.
However, subsequent studies found that the gel gave no significant protection against HIV.
Professor Salim Karim, lead investigator and director of Caprisa, said in the latest study researchers found that Tenofovir gel reduced the herpes virus by 51 percent.
The trial followed some 400 participants.
The herpes virus type 2 was measured at 10.2 cases per 100 person-years in the group using the Tenofovir gel compared to 21 cases per 100 person-years in women who received a non-effective gel.
The study found that the gel’s effectiveness increased in relation to its concentration. Researchers found that the herpes virus incidence rate among the women with vaginal Tenofovir concentrations of 10mg/ml or more was 5.7 cases per 100 person-years as compared to 15.5 cases per 100 person-years with no detectable vaginal Tenofovir gel.
Karim said: “The overall incidence rate of 15.5 cases per 100 person-years means that if 1 000 persons who were herpes simplex virus- (HSV) 2-negative at the beginning of the year were tested one year later, 155 of these people would be HSV-2 positive.
“In the Tenofovir gel arm, of every 100 women who were HSV-2 negative at the beginning of the year, 10.2 were HSV-2-positive at the end of the year – and in the placebo arm, of every 100 women who were HSV-2-negative at the beginning of the year, 21 were HSV-2 positive at the end of the year.”
While the use of Tenofovir gel by women in the original trial led to a 51 percent reduction in HSV-2 acquisition, women who used the gel during most of their sexual encounters experienced a 71 percent reduction.
Karim said that where interventions to reduce herpes virus infection – including condoms, circumcision and antiviral treatment among heterosexual couples – were limited, Tenofovir gel had so far proved to be the most effective treatment of its kind – giving 51 percent protection as compared with only 6 percent and 48 percent protection given by existing prevention interventions.
“Globally, Herpes simplex virus type-2 is among the most common sexually transmitted infections and is the leading cause of genital ulcers.
“Tenofovir gel could be used as an alternative HSV-2 prevention strategy for women unable to negotiate condom use.
“Further, given the close association between HSV-2 infection and the increased risk of HIV acquisition in women, Tenofovir gel has the potential to impact the global HSV-2 burden and indirectly impact HIV acquisition,” said Karim.