The relationship between the magnitude of the specific antibody response to experimental Salmonella enteritidis infection in laying hens and their production of contaminated eggs

Detecting infected laying flocks is a vital part of many efforts to control egg-associated transmission of Salmonella enteritidis to humans. The relat ionship between the development of a specific antibody response in infected hens and the deposition of S. enteritidis in eggs is important for establi shing the epidemiologic relevance of serologic testing methods. In two tria ls, laying hens were infected with large oral doses of phage types 13a and 14b isolates of S. enteritidis. Approximately 38% of all infected hens prod uced at least one contaminated egg, at an overall incidence of 5.2%, betwee n 3 and 23 days postinoculation. As determined by enzyme-linked immunosorbe nt assay with an S. enteritidis 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 conta mination, a consistently direct relationship was not evident between the ma gnitude of the antibody responses of individual hens and the frequency at w hich they laid contaminated eggs. Accordingly, although serologic tests can be valuable screening tools for preliminary detection of S. enteritidis in fections in poultry the magnitude of the antibody responses detected in ind ividual hens may not predict the overall risk of egg contamination associat ed with particular laying flocks.