"Indisposed" is really enough for me. I don't want to know that so-and-so ate a bad prawn. I just don't.
I understand that you don't want your team accused of being wimps, or you don't want some player to come under fire unfairly for being a lazy jackass when in fact he just has food poisoning. Or whatever. So you give lots of information. Right now you probably don't want to say "flu-like symptoms," on account of the hysteria, and that's fine.
But. Figure something else out. "Gastro-intestinal" is a word I never want to hear during a sporting event. Ever.