Abstract
The results from a survey for proliferative kidney disease (PKD) and renal myxosporidiosis in wild salmonids from rivers in England and Wales are presented. One hundred and eighty‐five salmon, Salmo salar , 235 brown trout, Salmo trutta , 16 charr, Salvelinus alpinus, and five grayling, Thymallus thymallus, were obtained from 23 locations on 16 rivers between July and October 1997. They were examined for the presence of clinical PKD and for histological evidence of infections with Tetracapsula bryosalmonae and other renal myxozoans. Prevalence of infection with T. bryosalmonae detected histologically in brown trout varied from 11 to 43% in enzootic rivers and was only found in salmon in two rivers at low prevalence. Nephromegaly was positively associated with PKD in brown trout but in salmon mild nephromegaly was only associated with infection with an unidentified Chloromyxum sp.