a1 Public Health Laboratory, Church Lane, Exeter EX2 5AD, UK
a2 PHLS Division of Enteric Pathogens, 61 Colindale Avenue, London NW9 5HT, UK
Over 5700 hens eggs from 15 flocks naturally infected with Salmonella enteritidis were examined individually for the presence of the organism in either egg contents or on shells. Thirty-two eggs (0·6%) were positive in the contents. In the majority, levels of contamination were low. Three eggs, however, were found to contain many thousands of cells. In eggs where it was possible to identify the site of contamination, the albumen was more frequently positive than the yolk. Storage at room temperature had no significant effect on the prevalence of salmonella-positive eggs but those held for more than 21 days were more likely (P < 0·01) to be heavily contaminated. In batches of eggs where both shells and contents were examined, 1·1% were positive on the former site and 0·9% in the latter.
(Accepted December 17 1990)