A couple of helpful comments on possible causes of the Roseville wedding outbreak. John Brooks from New Zealand:
You are correct, Bill. Infective agents such as bacteria and viruses usually take some hours to have an effect – they need to multiply to levels that cause a response in the patient.
This sounds more like a true poisoning – either ingestion of pre-formed bacterial toxin or a chemical accidentally added to the food. Were shellfish on the menu?
I guess that another possibility is a "pre-match function" held earlier in the day or the previous evening.
A couple of ideas: (1) staph enterotoxin, which is a toxin produced by the bacterium Staphylococcus aureus, and is known for causing acute vomiting and diarrhea just 2 hours after ingesting food stuff that has undergone temperature abuse. The symptoms are severely incapacitating, with few known lethal cases (if any). Or, Bacillus cereus toxin (common to rice dishes). Or (2) bacillus cereus, an endemic, soil-dwelling, Gram-positive, rod-shaped, beta hemolytic bacterium. Some strains are harmful to humans and cause foodborne illness, again wihin a short time after ingestion.