Re: Help please!
Since she was not actually sick herself, you could not have caught anything from her. I know it's tempting to think that she might have somehow been covered head to toe in viral particles from her parents, but believe me, if she had any viral particles on her at all, she would have been sick herself. The fact that she isn't tells me that she washes her hands well, and I expect she washed her hands before meeting you too.
Feel free to invite her to your house as soon as 48 hours after her parents have stopped being ill, if it makes you feel any better then have her head to the bathroom and wash her hands as soon as she comes in before touching anything, that way you've got a peace of mind guarantee that she's not bringing any germs into the house (even though she wouldn't be anyway, but you know, if it helps lower your anxiety I'm sure she won't mind).
Like I said above, she won't have given you any germs from her touching your hair, the only way she'd have given you any germs would have been if she herself had been ill, but she wasn't ill when you met, and therefore you'll be absolutely fine. Don't let this terrible phobia stop you from seeing your friend, I promise you, 48 hours is long enough. People in the food industry go back to work just 48 hours after infection, because the science tells us that people are significantly less infectious after this time, to the point where they are considered low enough risk to handle food (provided they wash their hands obviously).
Listen to the science, don't listen to your phobia, you'll be fine, I promise
The frog has retired. Occasionally he reads PMs, when he isn't hopping around happily from one lily pad to another. He wishes you all the very best, and hopes that you find the archive of his posts informative.