Submitted to: Journal of Aquatic Animal Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2008
Publication Date: 3/15/2008
Citation: Camus, A.C., Shewmaker, P.L., Mauel, M.J., Wise, D.J. 2008. Streptococcal Arthritis, Osteolysis, Myositis, and Spinal Meningitis in Channel Catfish Ictalurus punctatus Broodstock. Journal of Aquatic Animal Health. 20:54-62.
Interpretive Summary: This report details findings of an investigation into complaints by commercial fingerling producers of low-grade mortalities, poor reproductive success, emaciation, skin lesions, and severely arched backs among broodstock of channel catfish Ictalurus punctatus. The agent (Streptococcus ictaluri) is identified and the disease characterized.
Technical Abstract: This report details findings of an investigation into complaints by commercial fingerling producers of low-grade mortalities, poor reproductive success, emaciation, skin lesions, and severely arched backs among broodstock of channel catfish Ictalurus punctatus. Gross lesions involved the jaw, fin bases, and vertebral column. Jaw and fin lesions consisted of small hemorrhagic ulcers and exudate-filled tracts that communicated with underlying joints and destroyed their articular surfaces. Spinal changes, recognized grossly by severe arching of the proximal vertebral column, resulted from the collapse and displacement of vertebral bodies, causing compression of the spinal cord. Affected vertebrae were lysed by pyogranulomatous inflammation that infiltrated into adjacent muscle and the spinal canal. A Streptococcus-like organism was visualized in exudate and isolated repeatedly from lesions, but only once from the kidney of a single fish. Preliminary analysis of a 16S ribosomal DNA sequence showed a close relationship to S. iniae, S. parauberis, and S. canis. Koch's postulates were fulfilled after challenge with and reisolation of the agent from identical lesions that appeared at fin bases at 2 weeks postinjection. Historical evidence and gross and microscopic findings imply the presence of a pathogen of low virulence that is capable of producing severe localized infections after a brief period of septicemia. The disease presents as a chronic debilitating syndrome that is sufficient to inhibit mobility, feeding, and reproductive activity in affected fish. Complete biochemical and molecular characterization of the bacterium (published elsewhere) has established the agent as a novel species, S. ictaluri.