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Transmission of the microsporidian gill parasite, Loma salmonae

Published online by Cambridge University Press:  13 August 2007

Joy A. Becker  and
David J. Speare
Joy A. Becker
Affiliation:
Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, C1A 4P3, Canada School of Aquaculture University of Tasmania, Launceston, Tasmania7250, Australia
David J. Speare*
Affiliation:
Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, C1A 4P3, Canada
*
*Corresponding author. E-mail: speare@upei.ca
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Abstract

Since it was first reported in 1987 at a hatchery in British Columbia, Loma salmonae has become increasingly important as an emerging parasite affecting the Canadian salmonid aquaculture industry. L. salmonae causes Microsporidial Gill Disease of Salmon (MGDS) in farmed Pacific salmonids, Oncorhynchus spp., resulting in respiratory distress, secondary infections and high mortality rates. In the last decade, laboratory studies have identified key transmission factors for this disease and described the pathogenesis of MGDS. L. salmonae enters the host via the gut, where it injects sporoplasm into a host cell, which then migrates to the heart for a two-week merogony-like phase, followed by a macrophage-mediated transport of the parasite to the gill, with a final development stage of a spore-laden xenoma within the endothelial and pillar cells. Xenoma rupture triggers a cascade of inflammatory events leading to severe, persistent, and extensive proliferative branchitis. The development of robust and reliable experimental challenge models using several exposure methods in marine and freshwater environments with several fish hosts, is a primary reason for the success of scientific research surrounding L. salmonae. To date, demonstrated factors affecting MGDS transmission include host species, strain and size, the length of contact time between naïve and infected fish, water temperature and flow rates.

Keywords

Loma salmonaeMicrosporatransmissionsalmonidhost–parasite interactionlife cycle
Type
Review Article
Information
Animal Health Research Reviews , Volume 8 , Issue 1 , June 2007 , pp. 59 - 68
Copyright
Copyright © Cambridge University Press 2007

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