'Patient Zero' did not cause HIV outbreak in US, new study says

A long-held theory that a flight attendant known as "Patient Zero" caused the spread of HIV in America has finally been disproven after scientists analysed archived blood samples.

The experts also believe the virus started in New York in the early 1970s, and not Los Angeles in the early 1980s, as had been thought.

Gaetan Dugas was identified in a 1987 bestselling book - And the Band Played On by Randy Shilts - as playing a key role in the spread of the virus.

But a new study, led by Dr Michael Worobey from the University of Arizona, has shown he was simply one of many people caught up in the outbreak.

More than 2,000 blood serum samples were collected, belonging to gay men who were tested for hepatitis B in 1978 and 1979.

Three samples from San Francisco, and five from New York, contained enough traces of HIV to enable researchers to piece together the virus' entire genetic sequence.

The team also managed to sequence the full HIV code from Mr Dugas' sample.

Mr Dugas, a Canadian who worked for Air Canada, had become associated with HIV via a study conducted by the US' Centers for Disease Control and Prevention (CDC).

He was labelled "Patient O" because he was from outside California, where the outbreak was believed to have started at the time.

Researchers from the CDC discovered that several men from southern California, suffering from a lethal lung infection, were linked via sexual relations.

As they conducted their interviews, tracing the men's social network, Mr Dugas' name repeatedly cropped up.

The letter "O" later became confused with the number "0" and, in time, Dugas became known as "Patient Zero", implying he had been the first person infected with HIV.

He died in Quebec City in 1984 from kidney failure, linked to AIDs.

A medical historian from Cambridge University who co-authored the new study, Richard McKay, said: "This individual was simply one of thousands infected before HIV was recognised.

"Dugas is one of the most demonised patients in history."

The new analysis has also enabled researchers to construct an HIV "family tree".

Dr Worobey thinks a human was first infected by a chimp in Africa in the early 20th century.

Meanwhile the virus that led to the US outbreak first emerged from Africa in the mid to late 1960s, causing an outbreak in the Caribbean.

That strain arrived in New York from Haiti in 1970 or 1971.

The virus is thought to have arrived in San Francisco in 1975.

The first five case cases of AIDs were diagnosed in California in 1981.

HIV/AIDs has claimed more than 650,000 lives in the United States.