Polio vaccine trials are ruled out as origin of Aids

A PANEL of distinguished scientists has dismissed suggestions that polio vaccine trials in central Africa 35 years ago were responsible for the Aids epidemic.

The experts, drawn from some of the most prestigious research centres in the US, said the probability of the trials causing the inoculation of humans with an Aids virus found in monkeys to be 'extremely low'.

The allegations, which surfaced in the Lancet and Rolling Stone magazine in March, centre on the relationship between the simian Aids virus, SIV, found to infect a high proportion of African green monkeys, and the human Aids virus, HIV. Many scientists believe HIV evolved from SIV by crossing from monkey to man.

Tom Curtis, a freelance journalist and author of the Rolling Stone article, suggested that the route was the inoculation of 300,000 people in the Belgian Congo towards the end of 1957.

The American vaccine was made by infecting monkeys' kidney tissue with attenuated strains of the polio virus. Mr Curtis said the tissue could have been contaminated with SIV.

However, the scientific team said it was unlikely the SIV would have contaminated monkey tissue, or survived the cycles of freezing and thawing that the vaccine was subjected to. The team also cites one the first documented cases of Aids, in a sailor who died in 1959. His stored blood was later found to be infected with HIV which resulted from infection before the Congo trials were carried out.