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United States Department of Agriculture

Agricultural Research Service


Location: Warmwater Aquaculture Research Unit

Title: Myxobolus Neurophilus: Morphologic, Histopathologic and Molecular Characterization

item Khoo, L
item Rommel, F
item Smith, A
item Griffin, M
item Pote, L

Submitted to: Diseases of Aquatic Organisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2009
Publication Date: 2/24/2010
Publication URL:
Citation: Khoo, L., Rommel, F.A., Smith, A.A., Griffin, M.J., Pote, L.M. 2010. Myxobolus Neurophilus: Morphologic, Histopathologic and Molecular Characterization. Diseases of Aquatic Organisms. 89:51-61.

Interpretive Summary: Characterization of the myxozoan parasite Myxobolus neurophilus will help researchers/fish health professional definitively identify this parasite that appears to be wide spread in yellow perch populations. This may hopefully enable the identification of the intermediate host and may assist in commercial yellow perch production.

Technical Abstract: Archived tissues from affected yellow perch (Perca flavescens) as well as fresh submissions of juvenile yellow perch, walleye, fathead minnows, golden shiners and smallmouth bass cultured in the same pond or from a shared water source were examined. Archived tissues were sectioned and stained with hematoxylin and eosin or with Giemsa revealing myxospozoan spores consistent with Myxobolus neurophilus. These were found beneath the ependymal lining of the central canal of the brain or free within the stratum periventriculare with minimal or no inflammation. Unstained and stained (Wright Giemsa or Lugol’s iodine) touch impressions of the brains from all 5 species were prepared, examined microscopically. Only yellow perch were affected by similar myxozoan spores which were Giemsa positive with no iodinophilius vacuoles evident. Portions of the affected brains were fixed in 10% neutral buffered formalin. Pseudocysts containing spores were evident only in the brains and spinal cords of yellow perch in the histological sections. Mild mononuclear meningoencephalitis was present when the spores appeared outside of the pseudocysts. Brains fixed in 5% gluteraldehyde for scanning electron microscopic examination revealed spores with a smooth capsular surface. Phylogenetic analysis of 18S SSU rDNA of the spores revealed no direct matches to sequences available via Genbank and placed the organism within the family Myxobolidae. Aquatic annelids from sediment obtained from the affected pond were negative for actinospores.

Last Modified: 09/20/2017
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