Characterization of Seven Outbreaks of Hemorrhagic Hepatopathy Syndrome in Commercial Pullets Following the Administration of a Salmonella Enteritidis Bacterin in California

SUMMARY Between April 2013 and April 2015, seven flocks belonging to three different major commercial egg producers inCalifornia experienced a mild increase in mortality 2 to 3 wk after administration of Salmonella Enteritidis bacterins. Strains of chickens involved were H&N (flock A1, A2, B2, C1, C2, and C3) and Lohmann white (flock B1). Vaccination was administered individually through injection either in the breast muscles or subcutis in the legs between 11 and 18 wk of age in all flocks. Clinical signs ranged from inapparent to lameness, reluctance to walk, greenish diarrhea, and retching-like symptoms. The mortality ranged from 0.16% to 1.38% per week, with the highest peaks occurring usually 2 to 3 wk postvaccination, and then declined rapidly. Postmortem examinations revealed enlarged livers with disseminated hemorrhages and pale foci of necrosis. Also, severe extensive hemorrhages in the intestine, heart, and proventriculus were observed in a few birds. Various degrees of productive, exudative gia...