Salmonellosis in Trinidad II: evidence for transovarian transmission in farm eggs - abstract

ABSTRACT

The aim of this study was to determine whether farm eggs (contents and shells) in Trinidad are contaminated with Salmonella and to demonstrate if transovarian transmission occurs in these eggs. A total of 750 fresh eggs from 10 farms were cultured for Salmonella. The United States FDA Bacteriological Analytical Manual's Official Standard culture methods for Salmonella were used. Salmonella and S. enteritidis were detected in 9 of the 750 pooled eggshells' cultures, which has not been previously demonstrated in Trinidad. The spectrum of Salmonella serotypes isolated from the pooled egg contents were S. enteritidis (0.8 percent) and S. typhimurium (0.4 percent), and that isolated from the pooled eggshells was S. typhimurium (3.06 percent), S. enteritidis (0.67 percent), S. ohio, S. cerro, S. infantis (0.27 percent each) and S. heidelberg (0.13 percent). Salmonella was found in the egg contents of only three farms, but on the eggshells' surface from all 10 farms. This variation in isolation rate was found to be related to farm management and quality control practices. The contamination of the egg contents with S. enteritidis was deduced to be by the transovarian transmission process whilst S. typhimurium contamination of the egg contents was through faecal transmission. This study provides the first hard evidence for Salmonella and more importantly, S. enteritidis contamination of eggs, and demonstated transovarian transmission of S. enteritidis in eggs. This is of major public health significance since such eggs can be of grade A quality and widely consumed by unsuspecting consumers, resulting in salmonellosis. (AU)