Magazine article UNESCO Courier

From HIV to AIDS

Magazine article UNESCO Courier

From HIV to AIDS

Article excerpt

Is the human immunodeficiency virus (HIV) the result of germ warfare, genetic manipulation or monkey cell cultures? Is HIV really the cause of Aids?

The human immunodeficiency virus (HIV) is a new virus to humankind. Actually, there are two main types of the virus: HIV-1 is responsible for the worldwide pandemic of Aids; HIV-2, which can also cause Aids, occurs mainly in West Africa but is now spreading rapidly in some Asian countries such as India. There is evidence from stored blood samples that HIV first started to spread epidemically in the late 1970s, but Aids was not recognized as a distinct new disease until 1981.

Regrettably, although HIV and Aids are new, they are here to stay. HIV belongs to the family of retroviruses, in which the vital genes become inserted into our own genetic material in the chromosomes. Because HIV establishes long-term, persistent infection in this way there is no possibility of eradicating Aids, as the World Health Organization succeeded in doing with smallpox in 1977 and may achieve for poliomyelitis by the turn of the century.

When we are faced with such an appalling catastrophe as Aids, it is tempting to look for someone or some organization to blame for the situation. The world is not short of "conspiracy theories" on the origin of HIV - that it arose from germ-warfare research, from new genetic engineering technology or from growing the polio vaccine in monkey kidney cells. None of these fanciful, exciting ideas holds up to what we know about HIV, and its origin in humans may be much more mundane.

HIV-1 is related to a virus found in some chimpanzees and HIV-2 is even closer to a virus occurring naturally in sooty mangabey monkeys in West Africa. Thus it seems likely that HIV originally transferred from these animals to humans (a process called zoonosis), although HIV has now become a human-to-human infection.

Turning into Aids

HIV-1 is a usually fatal infection, whereas some people infected with HIV-2 get Aids and others remain well. HIV-1 actually kills a higher proportion of the people it infects than smallpox ever did, but unlike smallpox, the incubation period takes years, not days. During these years of relatively good health, the HIV-infected person may pass the virus on to others through sexual intercourse, from mother-to-child or via blood contamination. On average it takes about nine years to develop Aids in western countries though some infected people succumb to Aids much more quickly, and others have survived over fifteen years. In developing countries progression to Aids may occur two to three years earlier. During the long incubation period, HIV is active, particularly in the lymph glands. Yet it takes time to cause severe disease because the body has considerable reserves of the immune system to call upon which only slowly become exhausted owing to HIV infection.

A few investigators have queried whether HIV really is the cause of Aids, blaming lifestyle, especially drugs, instead. However the evidence for HIV's causing Aids has now become overwhelming. Quite simply, wherever Aids occurs, HIV has preceded it. HIV-negative people do not develop Aids, although there are some rare inherited or acquired immunodeficiencies that might occasionally be mistaken for Aids.

The only factor common to Aids, for example, in young adults in Africa, teenage girls in the sex bars of southeast Asia, homosexual men in North America, haemophiliacs in Europe or Japan and injecting drug-users in South America is HIV. Moreover, those infants who acquired HIV from their mothers die of Aids while those who escape the virus, even if their mothers have it, remain healthy.

Thus HIV is both necessary and sufficient to cause Aids. Yet many "co-factors" influence the speed at which Aids develops in the infected person. These co-factors include individual genetic make-up, age at the time of infection (older people tend to develop Aids quicker), nutrition, life-style including drug abuse and exposure to other infections. …

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