Details

Autor(en) / Beteiligte

• Rose, James D.
• Marrs, Glen S.
• Lewis, Christine
• Schisler, George

Titel

Whirling Disease Behavior and Its Relation to Pathology of Brain Stem and Spinal Cord in Rainbow Trout

Ist Teil von

• Journal of aquatic animal health, 2000-06, Vol.12 (2), p.107-118

Ort / Verlag

Taylor & Francis Group

Erscheinungsjahr

2000

Link zum Volltext

Quelle

Taylor & Francis Journals Auto-Holdings Collection

Beschreibungen/Notizen

• A long‐standing assumption about whirling disease is that the whirling pattern of swimming is caused by disequilibrium due to parasite‐induced damage of the auditory–vestibular apparatus or dysfunction of the nervous system related to vertebral column damage. The behavior of rainbow trout infected with Myxobolus cerebralis as 18‐d swim‐up fry was studied at 90 or 240 d after parasite exposure. These fish displayed a behavioral syndrome consisting of (1) sequences of tight turns (whirling), (2) periods at rest in which the tail was elevated higher than the head, and (3) episodes of postural collapse and immobility. In spite of these behavioral disturbances, the infected fish showed virtually no behavioral indications of impaired vestibular system function, such as difficulty maintaining an upright posture. Histological examination of these infected fish revealed that parasite invasion of the skull and vertebral column was associated with granulomatous inflammation that extended into the perineural cerebrospinal‐fluid‐containing space, producing ring‐like constrictions of the upper spinal cord and sometimes compressing and deforming the lower brain stem. In addition, some fish showed limited degeneration of pathways that connect the medulla with the spinal cord. A neurophysiological interpretation of the whirling pattern of swimming is presented, in which this abnormal behavior is proposed to result from spinal cord constriction, whereas episodes of collapse are more probably due to brain stem compression. The spinal cord and brain stem abnormalities that seem to be responsible for the abnormal behaviors in whirling disease appear to be caused largely by the invasion of granulomatous inflammation of the vertebrae and skull.