Put out of commission for a day or two by Norovirus.

http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-keyfacts.htm

http://blogs.scientificamerican.com/artful-amoeba/2012/01/17/misery-inducing-norovirus-can-survive-for-months-perhaps-years-in-drinking-water/