title: Epitheliocystis in Atlantic salmon, Salmo salar L., farmed in fresh water in Ireland is associated with 'Candidatus Clavochlamydia salmonicola' infection.
abstract: Intracellular inclusions containing chlamydia-like organisms are frequently observed in the gill epithelial cells of Atlantic salmon, Salmo salar L., cultured in fresh water in Ireland. In this study, the causative agent was identified in four separate freshwater sites, using 16s rRNA sequencing, as 'Candidatus Clavochlamydia salmonicola'. Histopathology and real-time (RT) PCR were used to further assess infections. The prevalence of infection ranged from 75-100% between sites and infection intensity was highly variable. No significant lesions were associated with these infections. As a diagnostic tool, RT-PCR proved marginally more sensitive than histopathology. The fate of 'Candidatus Clavochlamydia salmonicola' in Atlantic salmon post-seawater transfer was investigated in a 12-week marine longitudinal study. Both RT-PCR and histopathological examination indicate that the organism disappears from the gills 4-6 weeks post-transfer.
authors.affiliation: Vet Aqua International, Oranmore, Ireland. susievet@gmail.com
authors.forename: S O
authors.initials: SO
authors.lastname: Mitchell
authors.forename: T
authors.initials: T
authors.lastname: Steinum
authors.forename: H
authors.initials: H
authors.lastname: Rodger
authors.forename: C
authors.initials: C
authors.lastname: Holland
authors.forename: K
authors.initials: K
authors.lastname: Falk
authors.forename: D J
authors.initials: DJ
authors.lastname: Colquhoun
mesh_terms: D000818:Animals; D002693:Chlamydiaceae / Q000235:genetics / Q000502:physiology*; D002694:Chlamydiaceae Infections / Q000453:epidemiology / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D005393:Fish Diseases / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology; D005398:Fisheries; D005618:Fresh Water; D005880:Gills / Q000382:microbiology / Q000473:pathology; D007494:Ireland / Q000453:epidemiology; D008969:Molecular Sequence Data; D015995:Prevalence; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020317:Salmo salar; D012623:Seawater; D013997:Time Factors
chemical_list: D012336:RNA, Ribosomal, 16S