Relationship between age of flock seroconversion to hemorrhagic enteritis virus and appearance of adenoviral inclusions in the spleen and renal tubule epithelia of turkeys.

A retrospective study was conducted to evaluate the temporal relationship between flock seroconversion to hemorrhagic enteritis virus (HEV) and the appearance of adenoviral inclusions in the spleen and renal tubular epithelium. The study was conducted on samples of turkey poults submitted to the Fresno Branch of the California Veterinary Diagnostic Laboratory System during May to December 1988. The study included 78 submissions (four to eight poults per submission) of ages ranging from 6 to 15 weeks. Sera were tested for antibodies to HEV using the agar gel immunodiffusion test. Spleen and kidney samples were examined by light microscopy for the presence of inclusions in the mononuclear phagocytes of the spleen or in the renal tubular epithelium of the kidney. Logistic regression statistical analysis was used to evaluate the association between the age of the bird and the likelihood of the presence of inclusions in the spleen and kidney, as well as the likelihood of seroconversion to HEV. A significant association (P less than 0.05) was found between the presence of splenic inclusion bodies and the age of the bird. The probability of splenic inclusions was higher in younger birds (6 weeks of age), and decreased as the birds became older, approaching zero at 11 weeks of age. The kidney inclusions were significantly associated with age. The probability of detecting the inclusions increased with age, reached a maximum at 10 weeks, and then declined, approaching zero by 14 weeks. However, the probability of seroconversion to HEV increased significantly with age up to 10 weeks and then remained positive throughout the remainder of the study period.