Seventeen years after the discovery of the human immunodeficiency virus

Seventeen years after the discovery of the human immunodeficiency virus (HIV), thousands of people from around the world are gathered in Durban, South Africa to attend the XIII International AIDS Conference. At the turn of the millennium, an estimated 34 million people worldwide are living with HIV or AIDS, 24 million of them in sub-Saharan Africa. Last year alone, 2.6 million people died of AIDS, the highest rate since the start of the epidemic. If current trends continue, Southern and South-East Asia, South America and regions of the former Soviet Union will also bear a heavy burden in the next two decades.

Like many other diseases, such as tuberculosis and malaria that cause illness and death in underprivileged and impoverished communities, AIDS spreads by infection. HIV-1, the retrovirus that is responsible for the AIDS pandemic, is closely related to a simian immunodeficiency virus (SIV) which infects chimpanzees. HIV-2, which is prevalent in West Africa and has spread to Europe and India, is almost indistinguishable from an SIV that infects sooty mangabey monkeys. Although HIV-1 and HIV-2 first arose as infections transmitted from animals to humans, or zoonoses, both are now spread among humans through sexual contact, from mother to infant and via contaminated blood.

An animal source for a new infection is not unique to HIV. The plague came from rodents. Influenza and the new Nipah virus in South-East Asia reached humans via pigs. Variant Creutzfeldt-Jakob disease in the United Kingdom came from 'mad cows'. Once HIV became established in humans, it soon followed human habits and movements. Like other viruses, HIV recognizes no social, political or geographic boundaries.