The term "Patient Zero" was coined in March 1984 when the Center for Disease Control and Prevention (CDC), which had been tracking a disease that was affecting gay, and bisexual men in the US. Dugas was found to be the center of a network of men suffering from this disease and he was nicknamed "patient 0".
Further down the line, research went on to discover that HIV came originally from Africa to Haiti in 1966 and from Haiti to the United States in 1969, when Dugas would have been a teenager too young to be working on an airplane and be sexually active, which he began when he was nineteen. Which means that term “Patient Zero” technically is incorrect!!
A fellow Canadian John Greyson went on to undo this injustice by creating a film called Zero Patience. The film examines and contests the then established urban legend of the alleged introduction of HIV to North America by a single individual, Gaëtan Dugas. By the way, if you want to watch more movies about HIV/AIDS, I recommend you watch Dallas Buyers Club with Matthew Mcconaughey. It is so impressive!
Source: DAA website