ABSTRACT
Myxobolus albi was diagnosed in the cartilage of captive lumpfish (Cyclopterus lumpus) from 2 public aquaria. Eleven fish were affected, with the most common clinical signs being exophthalmos and grossly visible 1- to 2-mm white to tan scleral nodules. Myxozoan cysts were identified in the cartilage of the skull, branchial arch, sclera, vertebrae, tongue, all fin insertions, and the pectoral girdle. Cysts resulted in expansile, deforming, space-occupying lesions, resulting in exophthalmos but often lacking significant tissue damage or inflammation. Once cysts ruptured, free spores elicited a mild to marked inflammatory response. Spores measured 7.5 to 9.0 µm × 3.0 to 6.0 µm and contained 2 pyriform polar capsules oriented at one pole as well as occasional 1-µm-diameter basophilic nuclei. Identification was based on spore morphology together with polymerase chain reaction and sequence comparison of 18S ribosomal DNA. Isolates had 99% similarity to M. albi.
Subject(s)
Cartilage Diseases/veterinary , Fish Diseases/parasitology , Myxobolus/isolation & purification , Parasitic Diseases, Animal/parasitology , Perciformes , Animals , Base Sequence , Cartilage Diseases/parasitology , Cartilage Diseases/pathology , DNA, Protozoan/chemistry , DNA, Protozoan/genetics , Fish Diseases/pathology , Histocytochemistry/veterinary , Molecular Sequence Data , Myxobolus/genetics , Myxobolus/ultrastructure , Parasitic Diseases, Animal/pathology , Polymerase Chain Reaction/veterinary , RNA, Ribosomal, 18S/chemistry , RNA, Ribosomal, 18S/genetics , Sequence Alignment , Sequence Analysis, DNAABSTRACT
A light microscopy study of head cartilage tissue in rainbow trout alevins (Oncorhynchus mykiss) infected with the parasite Myxobolus cerebralis showed that, regardless of the presence or absence of whirling disease symptoms such as black tail and whirling swimming due to altered tail and spine morphology, some fish presented large amounts of spores lodged in the head after three months of infection. The spores were located in regions where the cartilage was extensively destroyed.
