A strain of the polio vaccine could have been responsible for transferring the HIV virus to humans, according to a recent article in Rolling Stone, extracted in The Economist.

Journalist Tom Curtis, working with AIDS activist Blaine Elswood and Raphael Stricker, an AIDs doctor and researcher, provides the following important links (although by themselves they do not prove a connection):

1. We know that some of the early Salk vaccines, all bred on the cells from monkeys' kidneys, were contaminated with other monkey (simian) viruses. One, the simian virus 40 (SV40), contaminated millions of people worldwide.

2. There is a simian immunodeficiency virus (SIV) similar to one strain of the human immuno deficiency virus (HIV-2), found in sooty mangabey monkeys from Africa.

3. HIV seems widest spread in Africa (and outside the high risk groups of male homosexuals, intravenous drug users and haemophiliacs) where SIV is endemic, making it likely that the virus shifted out of its host animal and into humans, particularly as the strain plaguing West Africa at the moment is HIV-2.

4. One polio vaccine developed by Hilary Koprowski, former head of the Wistar Institute in Philadelphia, was tried out on 300,000 people in central Africa in the late 1950s, where HIV is now most endemic.

5. There is evidence that some of Koprowski's live vaccine was contaminated evidence discovered by Albert Sabin, the man whose live vaccine eventually triumphed over Koprowski's for mass distribution.

6. The SIVvirus that is virtually identical to HIV-1, the more deadly strain in the West, has been found in chimpanzees. Although chimps weren't used to make vaccines, they were used in vaccine tests, and may have contaminated a laboratory.

The answer to these hypotheses largely depends on the kind of monkeys used. Koprowski maintains he used Indian monkeys, which do not carry SIV, although there was a ban at the time on exports of monkeys from India. The associate who grew the vaccine is dead.

Author Curtis has prompted Dr. Robert Bohannon of Baylor College of Medicine to request samples of the seed Koprowski vaccine used in the Congo so that he can test it for the presence of SIV. Not surprisingly, Curtis' theory has been met with hostility from medical camps like the World Health Organization, which says that finding out what caused AIDS is "irrelevant" to a cure.

There are also certain holes in the theory for instance, the fact that Koprowski's vaccine was widely distributed in Sweden, which has not suffered an epidemic of AIDS similar to Africa's.

Nevertheless, as Curtis sums up, whether or not his theory is proved right, the moral is about how the pressure to find a "cure" to a current plague can breed a entire new species of problem: ". . . with what we know now it's clear there was a certain hubris involved in the rough and ready campaigns to conquer polio. There is evidence that all three pioneers used vaccines inadvertently contaminated with viruses from a species dangerously close to our own. If the Congo vaccine turns out not to be the way AIDS got started in people, it will be because medicine was lucky, not because it was infallible."