Catching a cold

Chelsey
Long story short my brother and his gf came to visit us on Saturday and brought her 3 children the youngest is about 14 months and his nose was running off his face. Fast forward to today my throat is killing me and my nose is running, lo (who is 3 weeks) keeps sneezing and I'm terrified that she's coming down with it too. Any advice? 
I hate that they even came down knowing he was like that they are ridiculously inconsiderate.