The article is very well written and gives simple and logical explanations for a very complex subject, hence I will prefer to give some more general information about what a myth is, instead of explaining once again why these HIV/AIDS myths are false.
Myth is a very ancient word, since it belongs to the ancient Greek culture. This word was used to describe the stories about the origin of the world. Myth's characters can be both human and Gods so they actually imply that religion's beliefs are real and immutable. Every society need behavioural patterns to survive and these stories help in creating something for everybody to agree on.
Society needs these kinds of stories, but nowadays we all know that religion can't explain many of the problems of the world, so personal and shared opinions create a myth the same way that religion does. Some of those are called urban myths. The funny fact is that sometimes you end in believing in bulls*t even if we have enough knowledge to create myths that are actually true. This is not the case with a minorities-related issue like AIDS. The most common beliefs belong to the common people or, to say it better, to who don't belong to minorities. Unfortunately, HIV/AIDS is all about minorities, since it affects mostly gays, blacks, sex workers, drug users and so on.
A myth becomes a real prejudice because you believe in it -as you do with a religion- without even knowing what's real and what's not. This is the same as saying that a prejudice is like a myth where we are human and Gods at the same time, as a consequence having prejudices is like believing in bulls*t.
Source: DAA website