All I know is its going around. Cass has it, so do Tonks and McGonagall. Remus is so far immune and has taken over McGonagall's duties. Pomfrey's said its spreading and it looks like my case was a milder one as well.
Though really that damn itching made it seem worse than it was.
I owled Ron and Hermione but haven't heard anything back from them. Being in bed all week has sapped most of my strength but when I'm up to it I'm going to go visit them and make sure they're alright if they haven't owled.