2002 Volume 19 Issue 1 Pages 7-15
A survey was conducted to estimate the prevalence of Salmonella and antibodies for Salmonella Enteritidis (SE) in eggs retailed in Hokkaido. For this survey, 22, 120 eggs were purchased from farms and supermarkets from January 1998 to March 1999, in Sapporo. The eggs were produced by 31 farms across all of Hokkaido breeding a total of 4.22 million laying hens, accounting 66% of 6.37 million laying hens in Hokkaido.
No Salmonella was detected from any eggs tested, but 26 eggs from 13 samples were positive for egg yolk SE-antibody. One farm where one SE antibody positive egg was detected was surveyed environmentally for the prevalence of Salmonella, and Salmonellas were isolated from windowless hen houses. The bacteria were different from flock to flock. On another farm, two samples consisting of 30 eggs each yielded eight SE antibody positive eggs. Thirty spent hens obtained from this farm were tested for Salmonella isolation and SE antibody detection. Twelve of thirty hens (40%) were positive for Salmonella but neither SE nor SE antibodies were found.
These results indicate that the prevalence rate of Salmonella in retailed eggs in Hokkaido is lower than the model estimates described by Ebel & Schlosser [Int. J. Food Microbiol., 61, 51-62 (2000)], but SE-antibody detection rates for these eggs were considered to be on the same level with the model. SE-antibody positive eggs were detected among the eggs produced by the farm highly contaminated with SE or Salmonella. Thus, the monitoring the egg yolk SE-antibody of retailed eggs is useful for determinig the Salmonella contamination rate of each farm, which is valuable information for controlling Salmonella food poisoning by eggs and egg products.
