Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 29, 2000
Publication Date: April 4, 2001
Citation: Gast, R.K., Holt, P.S. 2001. The relationship between the magnitude of the specific antibody response to experimental salmonella enteritidis infection in laying hens and their production of contaminated eggs. Avian Diseases. Interpretive Summary: Detecting laying flocks infected with Salmonella enteritidis (SE) is an important part of programs designed to prevent the transmission of this pathogen to humans through contaminated eggs. The relationship between the antibody response to infection and the production of contaminated eggs by infected chickens is important for assessing the relevance of antibody detection. In this study, laying hens were experimentally infected with SE The magnitude of the antibody response from infected hens was compared to their patterns of production of internally contaminated eggs. About 38% of infected hens laid contaminated eggs, at an overall frequency of approximately 5%, between 3 and 23 days after infection. A test to detect antibodies to SE flagella determined that nearly 92% of hens produced such antibodies. Although hens with high antibody responses were associated with a distinctively high frequency of egg contamination, the relationship between these two parameters was not very consistent. Accordingly, althoug antibody tests appear to be useful tools for preliminary screening of laying flocks to detect SE infection, the magnitude of the antibody response by individuals hens may not be as useful for predicting the overall risk of egg contamination associated with the flock.
Technical Abstract: Detecting infected laying flocks is a vital part of many efforts to control egg-associated transmission of Salmonella enteritidis (SE) to humans. The relationship between the development of a specific antibody response in infected hens and the deposition of SE in eggs is important for establishing the epidemiological relevance of serological testing methods. In two trials, laying hens were infected with large oral doses of phage type 13a and 14b isolates of SE. Approximately 38% of all infected hens produced at least one contaminated egg, at an overall incidence of 5.2%, between 3 and 23 days post-inoculation. As determined by ELISA using an SE flagellar antigen, 91.7% of inoculated hens produced specific serum antibodies. Although hens with very high antibody titers were associated with a significantly elevated frequency of egg contamination, a consistently direct relationship was not evident between the magnitude of the antibody responses of individual hens and the frequency at which they laid contaminated eggs. Accordingly, although serological tests can be valuable screening tools for preliminary detection of SE infections in poultry, the magnitude of the antibody responses detected in individual hens may not predict the overall risk of egg contamination associated with particular laying flocks