I read somewhere about yellow coloured ones having some sort of disease or something that can cause people harm
A yellow salmon is not going to give you a disease... come on, how is a cold blooded animal disease going to infect you?
It's all media hyped BS pumped out by Morton. When she says "flu-like" that doesn't mean you're going to get the flu, it means that it is similar to a flu virus, but it only effects salmon and presents as flu like symptoms in salmon. In fact, for any one to make claims that it will make you sick is nonsense, mostly because no one even really knows what is causing the yellow salmon at this point. She'd of course like to believe it is fish farm caused, I highly doubt it.
The only thing you'll ever catch from fish is parasites, worms, etc if you don't cook them properly.