PATHOGENICITY AND PERSISTENCE OF SALMONELLA-ENTERITIDIS AND EGG CONTAMINATION IN NORMAL AND INFECTIOUS BURSAL DISEASE VIRUS-INFECTED LEGHORN CHICKS

The pathogenicity and persistence of Salmonella enteritidis (SE) phage type 8 and resulting egg contamination in normal and infectious bursa l disease virus (IBDV)-infected white leghorn chicks were evaluated ov er 34 weeks and in some birds over a 64-week period. Four hundred 1-da y-old specific-pathogen-free (SPF) straight-run white-leghorn chickens were allotted into four treatment groups: negative control, IBDV infe cted, IBDV+SE-infected, and SE-infected. Chicks were infected with IBD V at 1 day of age and with SE phage type 8 at 2 days of age. SE persis ted in the gut of more than 50% of the chicks of both SE-infected grou ps through 34 weeks postinoculation (PI), and SE could still be isolat ed from cloacal/rectal swabs taken at 64 weeks. IBDV+SE-infected chick s had severe gross lesions and significantly (P < 0.001) higher mortal ity (32%) than the negative control (1%), IBDV-infected (10%), and SE- infected (1%) groups. Gross lesions consisting of fibrinous pericardit is, perihepatitis, peritonitis, airsacculitis, and inspissated yolk we re observed only in the IBDV+SE-infected group. SE isolations from int ernal organs of chickens in the IBDV+SE infected group decreased from 83% at 8 weeks to 0% at 14 weeks PI; isolations from the SE-infected g roup decreased from 50% at 8 weeks to 0% at 10 weeks PI. Salmonella is olations increased from 0% to 14% in both groups at 18 weeks, correspo nding with the time of sexual maturity. Of the 1,050 eggs cultured fro m the IBDV+SE-infected group, SE was isolated from 88 shells, five alb umens, and two yolks. In contrast, of 1,258 eggs from the SE-infected group, 33 shells and none of the albumens and yolks were positive for SE. All eggs that had SE-positive contents also had SE-positive shells .