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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03593

    Muscular microsporidian infection in Arctic char Salvelinus alpinus from two lakes in Nunavik, Québec, Canada

    Marion Jalenques, Justin Sanders, Lilian Tran, Laurie Beaupré, Michael Kent, Stéphane Lair*

    *Corresponding author:

    ABSTRACT: Arctic char is an important cultural and subsistence resource for Inuit communities. Muscular infections by microsporidia were diagnosed for the first time in Arctic char originating from two different lakes in Nunavik (QC, Canada). The consumption of these infected fish was associated with digestive tract disorders in people. To better characterize microsporidiosis in these char populations, a cross-sectional study was conducted on 91 fish. This microsporidium was classified as a member of the Microsporidium collective genus by morphological evaluation and phylogenetic analysis using ssurDNA sequence data. The presence and severity of infection were determined histologically. Microsporidian infection occurred in 61% of the fish (56/91) and was significantly associated with an increase in their age, length and weight. The severity of infection (percentage of muscle area affected by microsporidia) was mild in most cases (<1% of the total muscle area). Based on multiple linear regression model, the severity of infection among infected fish was significantly greater in females and negatively correlated with the body condition. Despite a high prevalence, the low pathogenicity of the infection suggests that microsporidiosis has little impact on these char populations. Moreover, since digestive-tract disorders following ingestion of fish infected by microsporidia have never been reported in humans, it seems unlikely that it was responsible for the reported clinical signs. Anisakid larvae are occasionally observed in these char populations. Digestive-tract infection associated with ingestion of these larvae should thus be considered as a potential differential diagnosis in these Inuit communities.