Radiodiagnostic method for studying swimbladder inflammation caused by Anguillicola crassus (Nematoda : Dracunculoidea)

The nematode Anguillicola crassus appeared in Europe about 15 yr ago, and h as subsequently become recognised as a cause of major pathological lesions in the swimbladder of the European eel Anguilla anguilla. The radiographic method reported in this paper showed be a useful complement to diagnostic m ethods that have so far been based exclusively on fish dissection. Using th is method, the infection of the swimbladder and the severity of its patholo gical changes can be assessed in a reliable manner without causing damage t o the fish. By analysing radiographs of 45 eels from Lake Balaton, 5 stages of swimbladder lesions were distinguished. The method enables the examiner to draw conclusions on the air, worm and exudate content of the swimbladde r; however, data on thickening of the swimbladder wall can be obtained only indirectly. The radiograph also provides information on the air and worm c ontent of the pneumatic duct. Results obtained by radiography showed good a greement with dissection findings. Radiographic results are compared with p athological findings obtained from fish dissections separately for each sev erity grade of infection.