Procambarus clarkii Girard as a vector for the crayfish plague fungus, Aphanomyces astaci Schikora

Procambarus clarkii Girard, a native freshwater crayfish species of Lousiana, USA, was found to harbour the crayfish plague fungus, Aphanomyces astaci Schikora, in its cuticle as a benign infection. Under certain conditions, P. clarkii dies as a result of this parasite, and the A. astaci infection then becomes acute and can be transmitted to Astacus astacus (L.). Therefore, it is now shown that at least three different species of North American crayfish (Pacifastacus leniusculus Dana, Orconectes limosus Raff, and Procambarus clarkii Girard) can carry the crayfish plague fungus, A. astaci, can transfer the disease to other crayfish species, and under certain circumstances can die of its own infection.