The Medical Microbiology blog has a post on general diagnosis of urinary tract infection, enterocolitis, and foodborne illness. What they have to say about food poisoning is:
Food is an important mode of transmission of infectious diarrhea. Bacterial enters the food chain from animal infections, from poor hygiene during butchering, improper cleaning of storage and preparation areas and unclean utensils cause contamination of raw and cooked foods. Hens that are chronically colonized with salmonella produce eggs that may allow the multiplication of bacteria. Transmission of food poisoning is also facilitated where there is poor sanitation. In these situations, infections spread rapidly through the community, causing significant mortality. Cholera is capable of spreading world-wide. The temperature range in which most bacteria grow is between 40 degrees F (5 degrees C) and 140 degrees F (60 degrees C). Undercooking or improper processing of home-canned foods can cause very serious food poisoning.