Salmonella is a gram-negative, rod-shaped bacilli that can cause diarrheal illness in humans. They are microscopic living creatures that pass from the feces of people or animals to other people or other animals.
The Salmonella family includes over 2,300 serotypes of bacteria which are one-celled organisms too small to be seen without a microscope. Two types, Salmonella Enteritidis and Salmonella Typhimurium are the most common in the United States and account for half of all human infections. Strains that cause no symptoms in animals can make people sick, and vice versa. If present in food, it does not usually affect the taste, smell, or appearance of the food. The bacteria live in the intestinal tracts of infected animals and humans.
Salmonella bacteria have been known to cause illness for over 100 years. They were discovered by an American scientist, Dr. Daniel E. Salmon.
Photo by Jean Guard-Petter. USDA