Where are eggs usually infected with Salmonella enteritidis in the laying hen?

• A. Upper oviduct
• B. Lower oviduct
• C. Ovary
• D. Intestine

Answer: (A)

Salmonella enteritidis tends to contaminate eggs during their formation inside the hen’s reproductive tract, especially in the upper oviduct where the yolk and albumen are added to the developing egg. If the bacteria reach this region, they can become incorporated into the interior of the egg before the shell forms, leading to an internally contaminated egg that remains even when the shell is clean. Contamination from the lower oviduct would more likely affect shell membranes or the shell surface, and intestinal contamination would not typically produce internal egg contents contamination. So the upper oviduct is the site most associated with eggs being infected internally.