Abstract

Following the recent spreading of Viral Nervous Necrosis (VNN) among the main cultured marine fish species in Italy, an investigation on shy drum( Umbrina cirrosa )was carried out. Two outbreaks of the disease, showing a nervous symptomatology similar but different from the one described in the European sea bass (Dicentrarchus labrax) and causing high mortality rates (70-80%), were monitored. Sick fish (juveniles of 5 g and adults of 500-700 g) didn't present any external lesion, except a marked erosion of the head together with loss of one or both eye-globes. Peritoneum, guts, swim bladder and kidney were normal, while congestion and cerebral edema was observed in the cranium. Histological examination, performed on formalin fixed brain and eyes of moribund fish, allowed the detection of the typical lesions induced by the causative agent of the disease, a Nodavirus.