Studies concerning the role of Hemorrhagic Enteritis Virus in the pathology of turkeys conducted in the Department of Poultry Diseases in Olsztyn over the last 30 years

In Poland, Hemorrhagic Enteritis Virus (HEV) was first isolated in 1987. Over nearly thirty years numerous studies concerning the pathology of HEV infection of turkeys were conducted at the Department of Poultry Diseases in Olsztyn. The results of these studies contributed to one postdoctoral dissertation, five doctoral dissertations and one master's thesis, as well as numerous publications and papers presented at national and international conferences. Over time, through the use of state of art laboratory techniques, such as flow cytometry and molecular biology, it has been demonstrated that Polish isolates of HEV are low pathogenic, but they possess strong immunosuppressive activity; moreover, these viruses occur very frequently in turkey flocks and are involved in pathological conditions of turkeys in our country. It has been further demonstrated that even the HEV isolates which are low pathogenic cause a subclinical course of the disease which impairs both humoral and cell mediated immune mechanisms, leading to exacerbation of ongoing disease processes and decreased vaccine induced immunity development, which consequently cause large economic losses in the turkey industry.