DAO 79:219-228 (2008)  -  DOI: https://doi.org/10.3354/dao01832

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

R. Fleurance1, C. Sauvegrain2, A. Marques3, A. Le Breton4, C. Guereaud1, Y. Cherel1, M. Wyers1,*

1Department of Veterinary Pathology, UMR 703 INRA/ENVN, Nantes Veterinary School, BP 40706, 44307 Nantes cedex 03, France 2Aquanord, Terre des marins, 59820 Gravelines, France
3DRIM Dept BEE, UM2, case 080 Université Montpellier, 34095 Montpellier cedex 5, France
4Fish Health Consultant, 31330 Grenade sur Garonne, France
*Corresponding author. Email:

ABSTRACT: 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.


KEY WORDS: Enteromyxum leei · Myxidiosis · Parasitic enteritis · Histopathology · Sparus aurata


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Cite this article as: Fleurance R, Sauvegrain C, Marques A, Le Breton A, Guereaud C, Cherel Y, Wyers M (2008) Histopathological changes caused by Enteromyxum leei infection in farmed sea bream Sparus aurata. Dis Aquat Org 79:219-228. https://doi.org/10.3354/dao01832

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