Wikipedia: Patient Zero, Polio Vaccines, and HIV/AIDS
This article in the online encyclopedia Wikipedia discusses the theory that the AIDS epidemic in the U.S. was largely the result of the sexual exploits of Gaetan Dugas, a Canadian airline steward, who was dubbed Patient Zero in Randy Shilt’s book And the Band Played On.
There are also interesting articles on AIDS myths and urban legends and AIDS conspiracy theories.
Some have suggested that AIDS resulted from contaminated polio vaccines given in central Africa. Some say this is plausible others say the theory is unfounded.
When I first looked at the article about Patient Zero, it contained the statement:
The AIDS epidemic was started by contaminated batches of polio vaccine given to people in Burundi in central Africa.
I had never heard this theory before and was surprised to see it in an encyclopedia. When I returned to the article to write this post, the statement was gone. I thought I was becoming delusional. 
In trying to figure out what had happened to that statement, I learned how Wikepedia works; that anybody can post articles and anybody can edit them.