Persistence of Salmonella enteritidis from one day of age until maturity in experimentally infected layer chickens

In each of two replicate trials, 1-d-old chicks were inoculated orally with a phage type 13 Salmonella enteritidis isolate (resistant to nalidixic aci d). Although S. enteritidis was found in the livers, spleens, and ceca of a ll sampled chicks at 1 wk postinoculation, colonization generally persisted beyond 4 wk postinoculation only in the ceca. Nearly half of the remaining hens were still shedding S. enteritidis in their feces at 24 wk of age, bu t only 1 of 62 hens laid eggs that were internally contaminated with S. ent eritidis during the initial 4 to 6 wk of egg production. Chickens exposed t o S. enteritidis shortly after hatching can apparently remain infected unti l maturity, at which time they might produce contaminated eggs or spread th e infection to other susceptible, previously unexposed hens.