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Open Access Open Badges Letter to the Editor

Original observations of Desmozoon lepeophtherii, a microsporidian hyperparasite infecting the salmon louse Lepeophtheirus salmonis, and its subsequent detection by other researchers

Mark A Freeman1* and Christina Sommerville2

Author Affiliations

1 Institute of Biological Sciences & Institute of Ocean and Earth Sciences, University of Malaya, Kuala Lumpur, 50603 Malaysia

2 Institute of Aquaculture, University of Stirling, Stirling FK9 4LA UK

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Parasites & Vectors 2011, 4:231  doi:10.1186/1756-3305-4-231

Published: 13 December 2011


A microsporidian hyperparasite, Desmozoon lepeophtherii, of the parasitic copepod Lepeophtheirus salmonis (salmon louse), infecting farmed Atlantic salmon (Salmo salar), was first discovered in the west of Scotland in 2000. Heavily infected salmon lice are easily recognised as they have large opaque inclusions distributed throughout the body. The prevalence of salmon lice with visible signs of microsporidiosis can be up to 10% of the population from certain farm sites. The microsporidian was also isolated from the host Atlantic salmon suggesting it may have a two host life cycle. The authors believe that the infection in immunocompetent salmon may be latent, becoming acute during periods of infection with another pathogen or during sexual maturation. Since its first discovery in Scotland, Desmozoon lepeophtherii has been subsequently reported from Norway, and more recently from the Pacific coast of North America.

Desmozoon; Paranucleospora; Lepeophtheirus; Microsporidian; Copepod; opportunistic; Immunocompromised; Grilse