Histopathological survey of pathogens and commensals of white-clawed crayfish (Austropotamobius pallipes) in England and Wales

A histopathological survey of white-clawed crayfish (Austropotamobius pallipes) from six rivers in England and Wales was conducted between November 2007 and September 2011. A. pallipes bacilliform virus (ApBV) was present in four samples; infected crayfish showed pathological responses ranging from mild hypertrophy of infected nuclei and emargination of chromatin through to loss of architecture of the hepatopancreatic cells. Crayfish were found to be hosts to two different ciliate species, mites, nematodes, digeneans and the microsporidian Thelohania contejeani. The variation in disease presence between populations highlights the importance of conducting appropriate surveys of native crayfish prior to movement of animals to refugia sites for relocation, restocking or breeding programmes.