The presence of infectious pancreatic necrosis (IPN) virus in brook (Salvelinus fontinalis) and rainbow (Salmo gairdneri) trout was identified and further investigated. A high incidence of virus was found by virological examination of kidney tissue from yearling and older trout. By comparison, brook trout had a much higher incidence of virus than rainbow trout.
The virus was isolated most frequently from the kidneys of both species of trout. These findings indicate that the examinations of peritoneal washes and feces is not adequate for the detection of IPN carrier fish.