SURVEYS OF SALMONELLA-ENTERITIDIS IN UNPASTEURIZED LIQUID EGG AND SPENT HENS AT SLAUGHTER

In a 1995 national survey of 937 unpasteurized liquid egg samples coll ected in breaker plants, 179 of 937 samples (19%) were Salmonella ente rica serotype Enteritidis (S. Enteritidis) positive. The proportion of unpasteurized liquid egg samples positive for S. Enteritidis was high est in the Northern Region where 106 of 267 samples collected (40%) we re S. Enteritidis-positive. These Northern Region results were over th ree times the S. Enteritidis prevalence detected from the other three regions, whose results ranged between 10% and 12% S. Enteritidis-posit ive samples. In a 1995 national survey of spent hens at slaughter, 136 of 305 flocks (45%) had at least one S. Enteritidis-positive pooled s ample detected. Flock prevalence was highest in the Northern and Centr al Regions (64% and 40%, respectively); Southeastern and Western Regio nal flock prevalence levels were much lower (17% and 23%, respectively ). A comparison of the 1991 and 1995 unpasteurized liquid egg and spen t hen results suggest there has been no decline in S. Enteritidis occu rrence in the commercial egg industry between 1991 and 1995. Salmonell a Enteritidis phage type 4 was detected in the 1995 surveys of both sp ent hens and unpasteurized liquid egg but was not found in either surv ey in 1991. With the exception of one liquid egg sample from the South eastern Region, S. Enteritidis phage type 4 was found only in the West ern Region of the U.S. S. Enteritidis phage type 4 has emerged in the egg industry in the Western U.S. concurrently with an increase in the number of sporadic human phage type 4 isolates in California and Utah.