DAO 42:153-155 (2000)  -  doi:10.3354/dao042153

Transmission of the haplosporidian parasite MSX Haplosporidium nelsoni to the eastern oyster Crassostrea virginica in an upweller system

I. Sunila1,*, J. Karolus1, E. P. Lang2, M. E. Mroczka3, J. Volk1

1State of Connecticut, Department of Agriculture, Bureau of Aquaculture, Rogers Avenue, PO Box 97, Milford, Connecticut 06460, USA
21 Tower Hill Road, PO Box 314, Clinton, Connecticut 06413, USA
3Cedar Island Marina Research Laboratory, Riverside Drive, PO Box 181, Clinton, Connecticut 06413, USA

ABSTRACT: The haplosporidian oyster parasite MSX (Multinucleated Sphere X) Haplosporidium nelsoni was transmitted to eastern oysters Crassostrea virginica. Hatchery-raised, MSX-free juvenile oysters were placed in upweller tanks. Water to the tanks was filtered through a screen with 1 mm2 openings and originated from the water column overlaying naturally infected oysters beds (MSX prevalence 17 to 57%). MSX was diagnosed by histopathological analysis. MSX-disease (57% prevalence) with increased mortality (19%) was observed 11 wk after the beginning of the exposure and mortality of 80% after 16 wk. The study demonstrates transmission of MSX via water-borne infectious agents capable of passing through a 1 mm filter.


KEY WORDS: Haplosporidium nelsoni · Transmission · Crassostrea virginica


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