History of the HIV/AIDS epidemic with emphasis on Africa

History of the HIV/AIDS epidemic with emphasis on Africa
In 1981, a new syndrome, the acquired immune deficiency syndrome (AIDS), was first
recognized among homosexual men in the United States. By 1983, the etiological agent, the
human immunodeficiency virus (HIV), had been identified. By the mid-1980’s, it became clear
that the virus had spread, largely unnoticed, throughout most of the world.
The HIV/AIDS pandemic consists of many separate epidemics. Each epidemic has its own
distinct origin, in terms of geography and specific populations affected, and involve different
types and frequencies of risk behaviors and practices, for example, unprotected sex with multiple
partners or sharing drug injection equipment.
Countries can be divided into three states: generalized, concentrated and low.
Low
Principle: Although HIV infection may have existed for many years, it has never spread to
significant levels in any sub-population. Recorded infection is largely confined to individuals
with higher risk behaviour: e.g. sex workers, drug injectors, men having sex with other men. This
epidemic state suggests that networks of risk are rather diffuse (with low levels of partner
exchange or sharing of drug injecting equipment), or that the virus has been introduced only very
recently.
Numerical proxy: HIV prevalence has not consistently exceeded 5% in any defined subpopulation.
Concentrated
Principle: HIV has spread rapidly in a defined sub-population, but is not well-established in the
general population. This epidemic state suggests active networks of risk within the subpopulation.
The future course of the epidemic is determined by the frequency and nature of links
between highly infected sub-populations and the general population.
Numeric proxy: HIV prevalence consistently over 5% in at least one sub-population at highest
risk, and prevalence below 1% in the general adult population (age 15-49 years) in urban areas.
Generalized
Principle: In generalized epidemics, HIV is firmly established in the general population.
Although sub-populations at high risk may continue to contribute disproportionately to the spread
of HIV, sexual networking in the general population is sufficient to sustain an epidemic
independent of sub-populations at higher risk of infection.
Numeric proxy: HIV prevalence consistently over 1% in pregnant women.