Philasterides dicentrarchi (Ciliophora, Scuticociliatida) as the causativeagent of scuticociliatosis in farmed turbot Scophthalmus maximus in Galicia (NW Spain)

Two outbreaks of scuticociliatosis affecting farmed turbot Scophthalmus max imus in Galicia are described. Moribund fish showed cutaneous ulcers, darke ned skin, swimming behaviour alterations, exophthalmos, and/or abdominal di stension as a result of accumulation of ascitic fluid in the body cavity. C iliates were detected in fresh mounts of practically all organs and tissues , including the blood and ascitic fluid. Histopathological studies revealed severe encephalitis and meningitis (associated with different degrees of s oftening or liquefaction of the brain), necrosis of the hepatic parenchyme, severe oedema of the intestinal wall, degeneration of muscle fibres, hyper plasia of the branchial epithelium, and/or vascular and perivascular inflam mation. In some cases, parasites are surrounded by abundant monocytic and l ymphocytic infiltrate. We report the morphological and biometric characteri stics of this ciliate, which allow identification as Philasterides dicentra rchi. We discuss possible routes of entry into the host, and environmental factors possibly facilitating infection.