Histopathological changes caused by Enteromyxum leei infection in farmed sea bream Sparus aurata.

Histological examinations were carried out on the stomach, pyloric caeca and 4 different parts of the intestine, as well as the rectum, hepatopancreas, gall bladder and spleen of 52 sea bream Sparus aurata spontaneously infected by Enteromyxum leei. Fifteen fish from a non-infected farm were included as a control. Clinical signs appeared only in extensively and severely infected fish. We observed Enteromyxum leei almost exclusively in the intestinal tract, and very rarely in the intrahepatic biliary ducts or gall bladder. We observed heavily infected intestinal villi adjacent to parasite-free villi. Histological changes indicated a parasite infection gradually extending from villus to villus, originating from an initial limited infected area probably located in the rectum. The parasite forms were exclusively pansporoblasts located along the epithelial basement membrane. Periodic acid-Schiff (PAS)-Alcian blue was the most useful histological stain for identifying the parasite and characterising the degree of intestinal infection. We observed severe enteritis in infected fish, with inflammatory cell infiltration and sclerosis of the lamina propria. The number of goblet cells was considerably and significantly decreased in heavily infected fish. The intestines of 4 of the 5 survivor fish were totally free of parasites and showed severe chronic enteritis with a regenerative epithelium, suggesting that an acquired immune process may spontaneously eliminate parasites.

Retrospective study of Mycoplasma gallisepticum meningoencephalitis in six turkey flocks in western France.

Mycoplasma gallisepticum (MG) meningoencephalitis was diagnosed in six turkey flocks, from 1998 to 2005, in the western part of France. Affected birds were 8-11 weeks old and all displayed neurological signs, especially torticollis, with more than half having concomitant respiratory signs. Microscopical examination of brain samples from birds in all six flocks revealed similar lesions of acute to subacute multifocal parenchymal necrosis, perivascular cuffing, leptomeningitis and vasculitis. Birds from four of the six affected flocks were seropositive for MG and in birds from four flocks MG DNA was detected by polymerase chain reaction performed on tracheal swabs or on samples of formalin-fixed and paraffin wax-embedded brain. To our knowledge, this is the first pathological description of naturally occurring cases of turkey MG meningoencephalitis in Europe.