Identifying agent(s) associated. with poult enteritis mortality syndrome: Importance of the thymus

Poult enteritis mortality syndrome (PEMS), a highly infectious disease of y oung turkeys, causes serious financial losses to the turkey industry. Clini cally PEMS is defined by mortality profiles, diarrhea, growth depression, a nd immunosuppression. Although many viruses, bacteria, and parasites are fo und in PEMS-infected birds, the inciting agent remains unknown. Experimenta lly, PEMS can be reproduced by exposing naive poults to the intestinal cont ents from infected birds. Previous reports suggest that extraintestinal tis sues fail to reproduce the disease. Histopathologic examination of tissues from PEMS-infected poults suggested that the thymus exhibited the earliest signs of pathology. On the basis of these observations, we hypothesized tha t the thymus harbors an agent(s) involved in PEMS. In these studies, nai ve turkey poults were orally inoculated with a bacteria-free filtrate compose d of either the intestines and feces or the thymus from PEMS-infected birds and were monitored for clinical signs of PEMS. Poults exposed to a filtrat e composed solely of the thymus from PEMS-infected birds exhibited diarrhea , growth depression, mortality, pathology, and, most importantly, immunosup pression similar to poults exposed to the intestinal filtrate. The results of this study suggest that the thymus of infected birds harbors the agent(s ) that can reproduce a PEMS-like disease in turkey poults.