Jordi, if you can find evidence at the CDC that Gaetan Dugas really started
the AIDS epidemic (quote, unquote), I'd like to see it.  Otherwise, here's
something to read from Wikipedia.

In general, the term Patient Zero refers to the central or initial patient
in the population sample of an epidemiological investigation.
In particular, it refers to Gaëtan Dugas (February 1953 – March 30, 1984),
a Canadian airline steward who was "Patient O" (for "Out of California")
for an early epidemiological study on HIV by the Centers for Disease
Control. The "O" was generally misread as "Zero". His sexual partners were
surveyed for the disease in order to demonstrate that it was sexually
transmitted. Several of them were among the first few hundred to be
diagnosed with AIDS. Dugas eventually died not of AIDS or complications
related to AIDS, but of renal failure.
Dugas was not the first AIDS case in North America. However Dugas' role as
an early transmitter of the disease is notable for the fact that he was
infected with HIV and admitted (boasted) to having more than 250 sexual
partners a year all across North America for several years without using
protection. Dugas engaged in this behavior both before and after it was
discovered that the disease is transferred through sexual contact.
A misconception holds that Dugas was the first person to introduce the HIV
into North America. This myth may have its origins in sensationalism
surrounding Randy Shilts' book And The Band Played On which identified
Dugas by name as the "Patient Zero" in the CDC study. Neither the book nor
the film claims that Dugas was the first to bring the virus to North
America. Dugas is referred to as 'Patient Zero' not because he was the
first to be diagnosed with the disease but rather because at least 40 of
the 248 people diagnosed with AIDS by April 1982 had either had sex with
him or with someone who had. The CDC certainly did not conclude that Dugas
had introduced the HIV into North America, nor was he the first to have
his infection identified. In fact, the earliest identified case of human
being infected with the HIV dates back to 1959 in the Belgian Congo (later
Zaire and now the Democratic Republic of the Congo). HIV has also been
found in tissue samples of an American teenager who died in Missouri in
1969.
Furthermore, later research has cast doubt on the validity of the
conclusions that were advanced regarding Dugas' role as a major early
transmitter of HIV. At the time, it was believed that the HIV incubated
for about one year before becoming AIDS. The patients that were studied
due to their contact with Patient Zero had AIDS symptoms emerge on an
average of eleven months after having sex with him. Now that the
incubation period of the HIV is known to be, on average, longer than 12
months, it is unlikely that any of Patient Zero's sexual partners studied
were initially infected by him.
Speculation and uninformed sensationalism have advanced the theory that
"Patient Zero" of HIV, whoever the first human infected by HIV was, was
infected through sexual contact with chimps. This unfounded speculation is
rooted in the fact that a disease with identical characteristics as HIV
exists among simian species in Africa (SIV). This theory has been wholly
rejected by the scientific community. The predominant theory speculates
that zoonosis (transference of a disease between species) of HIV occurred
when a hunter (or hunters) came into blood contact with a simian infected
with SIV.
In addition to And The Band Played On, Patient Zero was a character in the
Canadian film Zero Patience, which refutes the myth along with many other
misconceptions surrounding the HIV and AIDS.
[edit]

See also
AIDS myths and urban legends