Well, I think the answer is in here somewhere:
http://aquaticpath.umd.edu/articles/kudoa.pdf
quote:
ABSTRACT: Ulcers in Atlantic menhaden Brevoortia tyrannus (Latrobe) (Clupeidae), observed along the
USA east coast, have been attributed to diverse etiologies including bacterial, fungal and, recently,
harmful algal blooms. To understand the early pathogenesis of these lesions, we examined juvenile
Atlantic menhaden collected during their seasonal presence in Chesapeake Bay tributaries from April
to October 1999 and from March to August 2000. We conducted histopathological examinations of
young-of-the-year fish from the Pocomoke River tributary, which has a history of fish mortalities and high
lesion prevalence. Kudoa clupeidae (Myxozoa: Myxosporea) spores were present in the muscles of fish
collected in both years. Of the fish assessed by histology in April, 5 to 14% were infected, while in May
90 to 96% were infected. Infection rates remained high during the summer. Mature spores were
primarily located within myomeres and caused little or no observable pathological changes. Ultrastructure
showed spores with capsulogenic cells bearing filamentous projections, and a basal crescentic
nucleus with mottled nucleoplasm containing cleaved, condensed chromatin. Also, a highly invasive
plasmodial stage of a myxozoan was found in the lesions of juvenile Atlantic menhaden. The plasmodia
were observed in fish collected between May and July, with the maximum occurrence in late June 1999
and late May 2000. Plasmodia penetrated and surrounded muscle bundles, causing grossly observable
raised lesions in 73% of all fish infected with this invasive stage. Plasmodia were also detected in the
visceral organs, branchial arches, and interocular muscles of some fish. Some of the invasive
extrasporogonic plasmodial lesions were associated with ulcers and chronic inflammatory infiltrates. The
plasmodial stage appeared to slough out of the tissue with subsequent evidence of wound healing.
Ultrastructure showed plasmodia with an elaborate irregular surface, divided into distinct ectoplasm and
endoplasm; the latter contained numerous spherical vegetative nuclei, secondary generative cells, and
occasional cell doublets. Our ultrastructural studies indicate that the plasmodial organisms, which are
important in the etiology of the skin lesions, are myxozoans, and they may represent early stages of
K. clupeidae.
The Myxozoa (etymology: Greek: myx- "slime" or "mucus" + zoa "animals") are a group of parasitic animals of aquatic environments. Over 1300 species have been described[1] and many have a two-host lifecycle, involving a fish and an annelid worm or bryozoan. Infection occurs through valved spores. These contain one or two sporoblast cells and one or more polar capsules that contain filaments which anchor the spore to its host. The sporoblasts are then released as a motile form, called an amoebula, which penetrates the host tissues and develops into one or more multinucleate plasmodia. Certain nuclei later pair up, one engulfing another, to form new spores.
This post edited by mpliny 08:41 PM 07/08/2008
http://aquaticpath.umd.edu/articles/kudoa.pdf
quote:
ABSTRACT: Ulcers in Atlantic menhaden Brevoortia tyrannus (Latrobe) (Clupeidae), observed along the
USA east coast, have been attributed to diverse etiologies including bacterial, fungal and, recently,
harmful algal blooms. To understand the early pathogenesis of these lesions, we examined juvenile
Atlantic menhaden collected during their seasonal presence in Chesapeake Bay tributaries from April
to October 1999 and from March to August 2000. We conducted histopathological examinations of
young-of-the-year fish from the Pocomoke River tributary, which has a history of fish mortalities and high
lesion prevalence. Kudoa clupeidae (Myxozoa: Myxosporea) spores were present in the muscles of fish
collected in both years. Of the fish assessed by histology in April, 5 to 14% were infected, while in May
90 to 96% were infected. Infection rates remained high during the summer. Mature spores were
primarily located within myomeres and caused little or no observable pathological changes. Ultrastructure
showed spores with capsulogenic cells bearing filamentous projections, and a basal crescentic
nucleus with mottled nucleoplasm containing cleaved, condensed chromatin. Also, a highly invasive
plasmodial stage of a myxozoan was found in the lesions of juvenile Atlantic menhaden. The plasmodia
were observed in fish collected between May and July, with the maximum occurrence in late June 1999
and late May 2000. Plasmodia penetrated and surrounded muscle bundles, causing grossly observable
raised lesions in 73% of all fish infected with this invasive stage. Plasmodia were also detected in the
visceral organs, branchial arches, and interocular muscles of some fish. Some of the invasive
extrasporogonic plasmodial lesions were associated with ulcers and chronic inflammatory infiltrates. The
plasmodial stage appeared to slough out of the tissue with subsequent evidence of wound healing.
Ultrastructure showed plasmodia with an elaborate irregular surface, divided into distinct ectoplasm and
endoplasm; the latter contained numerous spherical vegetative nuclei, secondary generative cells, and
occasional cell doublets. Our ultrastructural studies indicate that the plasmodial organisms, which are
important in the etiology of the skin lesions, are myxozoans, and they may represent early stages of
K. clupeidae.
The Myxozoa (etymology: Greek: myx- "slime" or "mucus" + zoa "animals") are a group of parasitic animals of aquatic environments. Over 1300 species have been described[1] and many have a two-host lifecycle, involving a fish and an annelid worm or bryozoan. Infection occurs through valved spores. These contain one or two sporoblast cells and one or more polar capsules that contain filaments which anchor the spore to its host. The sporoblasts are then released as a motile form, called an amoebula, which penetrates the host tissues and develops into one or more multinucleate plasmodia. Certain nuclei later pair up, one engulfing another, to form new spores.
This post edited by mpliny 08:41 PM 07/08/2008
