Cape Town — A large scale clinical trial to prevent HIV infection in women is to be launched in Zambia next month, Microbicide Trials Network (MTN) scientists announced at the fifth International AIDS society (IAS) meeting in Cape Town.

The study  Vaginal and Oral Interventions to Control the Epidemic (Voice) will help determine whether some of the same anti retrovirals (ARVs) could also be used to prevent HIV when they were administered as vaginal microbicide gel or as an oral tablet taken once a day.

In February this year, the first clinical trials of a vaginal gel intended to prevent HIV infection in women had showed encouraging signs of success. The trial funded by the National Institute of Allergy and Infectious Diseases (NIAID), was conducted in six African countries, including Zambia and the United States.

The first human clinical study to suggest that a microbicide, a gel, intended to prevent the sexual transmission of HIV and other sexually transmitted infections when applied topically inside the vagina or rectum-could prevent male-to-female sexual transmission of HIV infection.

The trials would also be conducted in Uganda, Malawi, Zimbabwe and South Africa. Voice study co-chair, Miker Chirenje said about 5,000 women would be enrolled in the trials, which would take about three and half years to complete with results expected in 2012.

Dr Chirenje said women represented about 60 per cent of adults living with HIV in sub Saharan Africa.

Women were twice as likely as their male partners to acquire HIV during unprotected sex, due in part to biological factors that made them susceptible to infection.

International AIDS Vaccine Initiative president, Seth Berkely said recently that the world wide economic recession had fuelled the debate about the best way to invest in global health but said given that AIDS was still the number one killer, the pandemic remained a top priority.

According to the World Health Organisation, microbicides are compounds that could be topically applied in the vagina or rectum to protect against sexually transmitted infections. They could be formulated as gels, creams, films, or suppositories.

Microbicides may or may not have spermicidal activity (contraceptive effect). At present, an effective microbicide is not available, and different candidates are in various stages of research.