The occurrence of Thelohania contejeani Henneguy, a microsporidian parasite of the crayfish Austropotamobius pallipes (Lereboullet), in Liguria Region (NW Italy)

The presence of the microsporidian parasite Thelohania contejeani Henneguy, responsible for porcelain disease (thelohaniasis), is reported in several crayfish populations inhabiting the Liguria Region. The infestation rate of this parasite was low, ranging from 0.17 to 3.7 per cent, and in two water courses it remained constant through years. However, we recommend performing periodically sanitary controls on the infected populations of Liguria and extending such controls to other populations not yet monitored. In fact, the virulence of the pathogens could increase owing to environmental stresses such as pollution, increase in crayfish density, paucity of food etc. We underline the importance, already suggested by other authors, of creating a central disease register to check the diffusion of the pathogens and facilitate the adoption of countermeasures.