What is the typical reservoir for Salmonella enteritidis in laying hens?

• A. House mice
• B. Rats
• C. Chickens themselves
• D. Cats

Answer: (A)

House mice are the typical reservoir in laying-hen operations because they live in and around the hen house, feed on the flock’s feed, and shed Salmonella enteritidis in their feces. This contamination of litter, surfaces, and feed creates a persistent source of infection that can spread to the birds and to eggs, even when the birds show few or no signs. Controlling mice—through sanitation, exclusion, and pest management—greatly reduces the introduction and spread of SE in the flock.

Cats are not reservoirs, as they are predators rather than carriers. Rats can harbor Salmonella, but in many layer facilities mice are the more common and persistent reservoir due to their closer association with feeding areas and nesting sites. While hens themselves can shed and carry the organism, the question refers to the typical reservoir in the environment of laying hens, which is the rodent population, especially house mice.