Incidence, aetiology and inspective notes of cottony in Mediterranean deep-water rose shrimp Parapenaeus longirostris (Crustacea: Decapoda)

Cottony of shrimp muscle is a pathological condition characterized by a progressive white opacity of musculature. Several causes have been accounted for this condition, including viruses, bacteria and parasites. In the present study incidence and etiology of this muscle alteration was evaluated in deep-water rose shrimp (Parapenaeus longirostris) captured in the Mediterranean Sea. A total of 190,000 either fresh or frozen P. longirostris coming from fishing area FAO 37-1 (n = 95.000) and 37-2 (n = 95.000) were evaluated for cottony by direct inspection, and lesion studied through histology and transmission electron microscope analysis. A comparison of bacteria found in specimens with and without cottony was also performed. A total of 126 cases (0.07%) of opaque muscle tissue were found. In all cases histopathological and ultrastructural observations revealed the presence of uninucleate microsporidian spores. No bacteriological differences were observed between cottony and non-infected shrimps. Although cottony does not represent a public health risk because these parasites do not constitute a zoonotic hazard for the consumer, it renders shrimps unmarketable and inedible.