Gah.
Am I being unreasonable in thinking if you're ill you make a slight effort to avoid people. Or at least tell them. 
We had friends over for dinner on Thursday, their baby was crawling all over the house, drooling on all of ds's toys. They kept giving him to me to hold. They were here for about 4 hours.
As they're leaving the Mum says "I have a confession to make, we're just at the tail end of an awful flu/cold bug, we've both been so sick." 
Fast forward to now and both ds and I have come down with it. We had a ton of stuff planned for this week which we now can't do, will be letting people down and losing money. If dh comes down with it we'll be fucked as this is he busiest week of the year workwise when we earn the most money. Which they are very aware of.
I'm not one of these 'keep kids indoors when they have a mild cold' type but I do think if two have you have been pretty ill it's manners to at least give people a heads up on it. And certainly not let your sick kid plaster everything in germs. Why do people not have basic fucking common sense?