Acquired immunodeficiency syndrome (AIDS) is the late stage manifestation of infection by the human immunodeficiency virus (HIV). The HIV virus lives in a type of immune cell (T-cell) which it destroys. Symptoms are sensitivity to opportunistic infections and/or malignancies and the mortality rate is very high, usually within 10 years of AIDS becoming manifest.
The syndrome results from a breakdown of the body's disease-fighting mechanism, the immune system, that leaves it defenceless against infections, such as pulmonary tuberculosis, Pneumocystis pneumonia, certain blood infections, candidiasis, invasive cervical cancer, Kaposi's sarcoma or any of over 20 other indicator diseases. The AIDS sufferer dies from one of these infections, compounded by general wasting and deterioration of body functions. No totally effective treatment is available, although promising drugs for remediation are available.
A striking feature of AIDS is the wide spectrum and frequency of life-threatening infections seldom seen in normal hosts. Four patterns of disease occur in AIDS patients. The pulmonary pattern, the central nervous system pattern, the gastrointestinal pattern and the pattern of fever of unknown origin. Most patients who recover from a given opportunistic infection subsequently either have a relapse or develop a new type of infection. Feelings of depression and isolation are common among AIDS patients and can be intensified if health care workers display fear of the syndrome.
AIDS takes ten years on average to develop. Because of this long lag time, AIDS cases will continue to develop from the existing pool of HIV-infected persons for some time to come, no matter how successful efforts are to curb the further spread of HIV.
Cases of acquired immune deficiency syndrome were first identified in the USA in 1981. There, AIDS was first called Gay-Related Immune Deficiency (GRID). By mid-1992, 6 US and 4 Spanish cases of AIDS symptoms without traces of the virus were found, which led scientists to question the existence of a third strain of HIV, thought to be similar to HIV1 and HIV2, but different enough to evade conventional HIV tests. The development of new HIV strains threatens to escape reliable modes of detection and preventative action.
Globally, there were an estimated 40 million people with AIDS in 2001, three-quarters of them in Africa. 37.2 million adults (17.6 million women) and 2.7 million children). 3 million died of AIDS in 2001 and another 5 million were newly infected. Cumulatively, 8.4 million people had died of AIDS by the end of 1996. The global incidences both for death and infection have been increasing at significant rates since AIDS was first detected in the 1980s. At the same time the geographic distribution of incidence has shifted. In 1997, the USA had a highest number of AIDS cases with 581,429; Brazil had 103,262; Tanzania had 82,174, Thailand 59,782, and France 45,395. Lately it is Africa, Asia and eastern Europe that have the most alarming infection and incidence numbers.