How can you tell the difference between food poisoning and a virus?

It's generally moot: Staph food poisoning is very severe, very sudden, and very brief. Other food poisoning outbreaks will affect multiple eaters almost identically. The gastrointestinal viruses run in small outbreaks in particular seasons. The two entities are seldom distinguished s they are self-limited. Salmonella and shigella might be cultured from the stool -- infections, not poisoning.