Is food poisoning contaigous?
Pour on the water, and consider adding V8 (the juice) and or Orange Juice.
There is some over the counter stuff out there that you should take at the FIRST signs of the flu, to help knock it down.
Considering you KNOW for sure they both have it, now might be a good time to have that stuff ready, so you can take it at the first hint of symptoms, or sooner.