A Study of the Lesions Induced in Seriola dumerili by Intradermal or Intraperitoneal Injection of Streptococcus dysgalactiae:

Intradermal and intraperitoneal injection of S. dysgalactiae resulted in moderate mortality. Grossly, there was microabscessation and/or granulomatous inflammation of the heart, caudal peduncle, pectoral and/or dorsal fin and olfactory region. The lesions in the atrial myocardium and arterial cone consisted of severe arterial thrombosis, granulomatous valvular endocarditis and epicarditis.

Detection of botulinum type E toxin in channel catfish with visceral toxicosis syndrome using catfish bioassay and endopep mass spectrometry. J Vet Diagn Invest 19:349–354 (2007). Visceral toxicosis of catfish (VTC) was first recognized in the spring of 1999 in the Mississippi Delta in channel catfish (Ictalurus punctatus).24 This syndrome is characterized by the sudden death of otherwise healthy market-sized fish when pond water temperatures are approximately 18 to 22uC. Because diagnostic submissions were negative for bacterial, parasitic, fungal, and viral pathogens, the etiology of this disease was considered to be a toxin.

Molecular detection of betanodavirus in wild marine fish populations in Korea. J Vet Diagn Invest 20:38–44 (2008). Viral nervous necrosis (VNN) is a worldwide disease affecting several species of cultured marine fish.  Betanodaviruses occur in large populations of wild marine fish in the

southern part of the Korean peninsula.

Two Independent Cases of Spontaneously Occurring Branchioblastomas in Koi Carp (Cyprinus carpio). well-demarcated, pale red nodular masses located at the left first branchial arch and the right pseudobranch, respectively. Histologically, the neoplasias were composed of blast-like cells that differentiated into cartilage and branchial lamellae embedded in abundant fibrous connective tissue. Based on these findings, a branchioblastoma was diagnosed.

Ultrastructural Examination of the Host Cellular Response in the Gills of Atlantic Salmon, Salmo salar, with Amoebic Gill Disease. Vet Pathol 44:663–671 (2007).  Amoebae were found either on the surface epithelium or with pseudopodia extending deeply into invaginations of epithelial cells. The amoebae had various densities along the plasma membrane and contained electron-dense deposits within their cytoplasm. Surface epithelial cells sloughed from the gills and had features consistent with apoptosis.  Affected areas of gills had fusion of secondary lamellae with interlamellar spaces occupied by mitotic epithelial cells andeosinophils. Eosinophils contained abundant fusiform-shaped granules that measured approximately 1 mm long and 360 nm wide. The granule consisted of an electron-dense matrix with a central inclusion that was less electron-dense, consisting of particulate and fibrillar material.

Severe Scuticociliate (Philasterides dicentrarchi) Infection in a Population of Sea Dragons (Phycodurus eques and Phyllopteryx taeniolatus). Vet Pathol 45:546–550 (2008).  Macroscopic lesions were confined to the skin with multiple, often hemorrhagic, ulcerations. Histologically, epidermal ulcers were associated with necrosis and inflammation of the underlying dermis and musculature. Numerous ciliates, with a morphology consistent with scuticociliates, were present in these lesions. In several animals these ciliates had invaded blood vessels and were detected in gills and internal organs including kidney, thyroid gland, and central nervous system (CNS).

Systemic iridovirus infection in the Banggai cardinalfish (Pterapogon kauderni Koumans 1933).  J Vet Diagn Invest 21:306–320 (2009). Virus particles were nonenveloped,  hexagonal,  with  a  central  electron- dense  nucleic  acid  core  surrounded  by  a  pale  zone that, in turn, was marginated by an outer, moderately electron-dense  nucleocapsid  layer  of  uniform  width. Basophilic  granular  cytoplasmic  inclusions  were  identified  in  cytomegalic  cells  often  found  beneath Endothelium (in gills). Gross-  hemorrhage  on renal and ovarian tissue, necrosis  of  branchial  microvasculature. Cytomegalic   cells   were also observed in the lamina propria and along the serosa of the stomach and intestine, in the  mesentery,   liver,  cranial   and  caudal   kidney, spleen,  hypodermis,  brain,  capillary  network  of  the choroid,  gas  gland  of  the  swim  bladder,  skeletal muscle,  and  ovary.

Characterization of Virus Distribution in Rock Bream (Oplegnathus fasciatus; Temminck and Schlegel) Infected with Megalocytivirus J. Comp. Path. 2009, Vol. 141, 63e6. Iridoviruses are large cytoplasmic DNA viruses with an icosahedral morphology. Iridoviridae family consists of five genera including Iridovirus, Chloriridovirus, Ranavirus, Lymphocystisvirus and Megalocytivirus. Iridoviral infections are one of the most prevalent viral diseases of cultured freshwater and marine fish species. Pathogenesis: The virus infects the leucocytes (mostly monocytes-no markers for differentiation) and the monocytes infiltrate various tissues.

Epizootic Ameloblastomas in Chinook Salmon (Oncorhynchus tshawytscha) of the Northwestern United States.  Vet Pathol 46:622–635 (2009). Bilaterally symmetrical, red, irregularplaques on oral mucosal surfaces, the lesions developed progressively into large, disfiguring masses. Histologic features of the tumors suggested that they were derived from the portion of dental lamina destined to form tooth root sulci; therefore, these neoplasms were diagnosed

as ameloblastomas. A few intracytoplasmic hexagonal structures, possibly consistent with viral particles (,100 nm), were observed ultrastructurally in a tumor cell.

Massive mortality of common carp in the St. Lawrence River in 2001: diagnostic investigation & experimental induction of lymphocytic encephalitis.pp302-10. May 2006  NW

A definitive single cause of the massive mortality that affected carp in the ST. Lawrence River in 2001 was not determined.

Exclusively affecting common carp (Cyprinus carpio carpio) in St. Lawrence River, Canada, during summer of 2001

Multifocal necrotizing dermatitis, necrotizing branchitis, coelomic inflammatory effusion, encephalitis, and erosive enteritis

The ultimate causes of mortality: Immunosuppression induced by stressors w/ opportunistic bacterial infection (Aeromonas hydrophila andFlavobacterium sp.) and possibly enhanced by an infection causing lymphocytic encephalitis (unknown etiology)

Correlation of Virus Replication in Tissues with Histologic Lesions in Atlantic Salmon Experimentally Infected with Infectious Salmon Anemia Virus:Infectious salmon anemia is a highly fatal disease of marine-farmed Atlantic salmon caused by ISA virus (family Orthomyxoviridae, genus Isavirus). Clinical disease is chr by exophthalmia, pale gills, ascites, congestion of gut, enlargement of liver and spleen, petechial hemorrhages in the visceral organs, severe anemia. Histo: hepatic necrosis, vasculitis and sinusoidal congestion—peliosis, renal interstitial congestion, tubular necrosis, congestion of branchial lamellar and filamental vessels, congestion and necrosis of the intestine, pyloric caeca, and increased erythrophagia in the spleen and kidney.

Gastric cryptosporidiosis in freshwater angelfish (Pterophyllum scalare). J Vet Diagn Invest 21:722–727 (2009). swollen  coelomic  cavities, protozoa  were  identified  both  histologically  and  ultrastructurally  associated  with  the  gastric mucosa.

Tetrahymena sp infections in lab Zebrafish- Comp Med 52(4): 363

Necropsy- swarms of ovoid-shaped, motile, ciliated protozoa with a “spiraling football” motion. Wet mount preparations of various water samples also contained high numbers of similar protozoa. Histologic examination of affected fry revealed numerous, periodic acid-Schiff-positive forms within the body coelom, and epithelial and muscle tissues.

The protozoa were consistent morphologically with members of the genus Tetrahymena, which is usually a free-living, nonpathogenic ciliated protozoa in fresh and saltwater environments. Relevant disease associated with Tetrahymena spp. in viviparous fish has been reported as a result of concurrent disease, immunosuppression, or poor water quality conditions

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