Marteiliosi in mitili (Mytilus galloprovincialis) allevati in Campania: caratterizzazione molecolare e valutazione dell'impatto zootecnico

Marteiliosis is a notifiable disease according to European Regulation and included in the list of the Organisation for Animal Health (OIE) in order to be managed and its transfer prevented. Marteilia refringens, is molluscan parasite protozoa belonging to the phylum Cercozoa, order Paramyxida with cell-inside-cell development. It causes filtration and nutrients absorption disorders, gametogenesis impairment and in severe infections it can result in death of the host species, affecting cultured mussels in terms of socio-economics impact. In this study, in view of importance of the mussel farming, was investigated the sanitary and zootechnical impact of M. refringens infection in Mytilus galloprovincialis in 11 farms of Campania. Prevalence and intensity of M. refringens type M infection, identified by PCR-RFLP, were evaluated by histological and cytological examinations. It was assessed M. refringens impact on health, gametogenesis, physiological state and commercial quality of mussels. It was evaluated the association between M. refringens prevalence and mussel farming area, temperature, heavy metals concentration and organic pollution. M. refringens was detected in winter and in autumn consistently with not exceeding temperatures 17°C. In the Flegrean area, infection prevalence was increased to 16°C, was maximum at 24°C and was decreased to 28°C. All M. refringens stages of development were detected in winter, located in the epithelium of digestive tubules. The finding of sporangia containing mature spore has indicated that the sporulation was occurred. The infection grade was severe but M. refringens did not affect gametogenesis and it caused no pathological damage in digestive gland, however, M. refringens infection influenced negatively the condition index and the resistance of the shell. M. refringens did not reduce the energy absorption but infected mussels used the energy reserves for the immune response induced by the parasite infection and the poor environmental quality.