Two isolates of Aphanomyces astaci obtained from diseased white-clawed crayfish (Austropotamobius pallipes) in Herefordshire, England were compared against representative isolates of three groups of the fungus found in Sweden and one from Spain by means of random amplification of polymorphic DNA (RAPD). The English isolates proved to be very similar to a Swedish strain which is considered to have been introduced from North America with shipments of the signal crayfish (Pacifastacus leniusculus) from 1970 onwards, and has since spread to indigenous populations of noble crayfish (Astacus astacus). This strain has not been found to be involved in recent incidences of crayfish plague in Turkey and Spain. It is therefore most likely that at least some of the outbreaks of crayfish plague in England resulted from imports of P. leniusculus from northern Europe after 1970, or directly from North America.
Cerenius, L.; Lilley, J.H.; Soderhall, K. RAPD evidence for the origin of crayfish plague outbreaks in Britain. Aquaculture (1997) 157 (3-4) 181-185. [DOI: 10.1016/S0044-8486(97)00153-1]