Food Safety Report: Walmart Supercenter, Davidson Avenue, Mt Vernon, Illinois, USA 2 years ago • details 6 Comments Comment Suspected food poisoning. Symptoms: Diarrhea, Nausea, Vomiting, Fever, Stomach Pain, Cramps, Chills Suspected source: Onions Onset: 4 to 12 hours Duration: Several days Sick: 2 people