The recognition of AIDS in Africa and Haiti soon after its emergence in the United States was just the first stirrings of an epidemic that was raging on every continent within ten years. Unlike well established infectious diseases, AIDS has been dubbed `the slow plague' by some commentators because of the way in which the disease spreads invisibly for many years before the first signs of its arrival in a region or population group. This has made governments in impoverished regions reluctant to adopt prevention policies until they see signs of AIDS; by then it is often too late to prevent a major epidemic.

The first region outside Africa and North America in which AIDS emerged was Europe, because of the continent's connections with both epidemics. South America was the next region to be affected, with Brazil suffering most. Caribbean states such as Haiti, the Dominican Republic and Trinidad also became affected at this time. But until the late 1980s most cases in these regions were probably a result of sex between men or transfusion with infected blood products. It was only in the late 1980s that the first evidence emerged of the spread of HIV through vaginal intercourse.

In 1987 the World Health Organisation began to characterise the spread of HIV according to different patterns. Pattern 1 countries were those in which the spread of HIV had occurred predominantly through sex between men, injecting drug use and blood products. Pattern 2 countries were those in which transmission had occurred primarily between men and women and through blood products and unsterilised needles. Pattern 3 countries were those in which the spread of HIV was very limited and in which cases of AIDS could be attributed to contact with Pattern 1 or 2 countries or the import of infected blood products. This classification is now questionable given the development of Pattern 2 and Pattern 1 type epidemics simultaneously in countries such as Thailand. The spread of HIV in Asia and Eastern Europe has challenged earlier assumptions about which societies would be vulnerable. In the 1980s Lee Kuan Yew, the Prime Minister of Singapore, expressed the view that the superior morals and sexual restraint of Asian people would minimise the threat of AIDS in South East Asia.

It was not until the mid-1980s that HIV began to spread in Asia and Eastern Europe, at first as a consequence of injecting drug use. In Thailand for instance, HIV prevalence amongst injecting drug users in Bangkok increased from virtually nil to 30% in less than six months following a prison amnesty which released HIV-positive drug users into the community in the autumn of 1987. Subsequently however, sexual transmission of HIV has taken place on a large scale.

HIV has continued to spread rapidly in Africa, India and the Caribbean. For further discussion see An Overview of the Global Epidemic in The Epidemiology of HIV.

Further reading

Jonathan Mann, Daniel Tarantola and Thomas Netter: AIDS In The World: A Global Report, Harvard University Press, 1993.