Vaginal microbicides for the prevention of HIV transmission

The human immunodeficiency virus (HIV) kills more people worldwide than any other infectious disease. Approximately 42 million people, mostly in Africa and Asia, are currently infected with HIV (Figure 3.1), and 5 million new infections occur every year (AIDS Epidemic Update, 2002). It is estimated that 22 milIion people have died since the first clinical evidence of AIDS (acquired immunodeficiency syndrome) emerged in 1981 ('Mobilization for Microbicides' ~ The Rockfeller Foundation). HIV is generally transmitted in one of three ways: through unprotected sexual intercourse, blood-to-blood contact, and mother-to-child transmission. Once the virus has entered the body, it invades the cells of the immune system and initiates the production of new virus particles with concomitant destruction of the immune cells. As the number of immune cells in the body slowly declines, weight loss, debilitation, and eventually death occur due to opportunistic infections or cancers. Although AIDS is presently incurable, highly active antiretroviral therapy (HAART), where a cocktail of potent antiretroviral drugs are administered daily to HIV-positive patients to control the viral load, has resulted in dramatic reductions in HIV-related morbidity and mortality in the developed world