Detection of Salmonella serogroup D-specific antibodies in the yolks of eggs laid by hens infected with Salmonella enteritidis.

Eggs laid by hens experimentally infected with Salmonella enteritidis were assayed for the presence of Serogroup D-specific yolk antibodies. Yolk antibodies were detected with S. enteritidis and Salmonella pullorum antigens in the microantiglobulin test as early as 9 days after inoculation of hens with S. enteritidis. Yolk antibody titers reached peak levels at 3 to 5 wk postinoculation and remained at detectable levels for at least 7 wk postinoculation in eggs from both orally inoculated and horizontally contact-exposed hens. Eggs laid by hens from commercial flocks implicated in epidemiological investigations of human S. enteritidis outbreaks were also tested. Serogroup D-specific yolk antibodies were detected in 5 to 22% of eggs from hens in houses identified as infected by bacteriological culturing of internal organs of hens for S. enteritidis.