What is the principal reservoir for nontyphoidal Salmonella enterica serotypes?

• A. Humans
• B. Food animals
• C. Water
• D. Birds

Answer: (B)

Nontyphoidal Salmonella enterica serotypes are maintained in animals raised for food, so the principal reservoir is food animals. These bacteria colonize the gut of poultry, cattle, and pigs and are shed in feces, leading to contamination of meat, eggs, and dairy products. Humans most often acquire illness by consuming or handling contaminated animal-origin foods, which is why food animals are viewed as the main source. Humans can become transiently infected and can spread the bacteria, but they are not the ongoing reservoir in nature. Water can spread contamination, but it serves as a vehicle rather than the reservoir, and while birds are important reservoirs for some serotypes, they’re encompassed under the broader category of food animals.