Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2023
Höfundar / Authors: Árni Kristmundsson (1), Ásthildur Erlingsdóttir (1), Mark A. Freeman (2) and Kalina H. Kapralova (1)
Starfsvettvangur / Affiliations: 1. Institute for Experimental Pathology at Keldur, University of Iceland, 2. Ross University School of Veterinary Medicine, St. Kitts West Indies.
Kynnir / Presenter: Árni Kristmundsson
Myxosporeans (Phylum Myxozoa) comprise a large group of pluricellular microparasites infecting fish. They have a complex life cycle, with annelids as definitive hosts and fish as intermediate hosts. Initially, twelve farmed Arctic charr were send for diagnosis to Keldur, due to abnormal mortality. Subsequently, hearts from wild Arctic charr were collected from four lakes in Iceland and examined for the presence of this parasite. The fish were examined using fresh mount preparation, histology and molecular methods (pcr and sequencing).
All the farmed fish were found infected with a myxozoan parasite in the heart muscle. Small plasmodia were scattered in the myocardium, each containing large numbers of tiny mature spores (<4µm). Associated with infections, was severe diffuse epicarditis and myocarditis, as well as a significant diffuse myodegeneration. At present, only few wild Arctic charr have been examined, however, a morphologically identical parasite has been identified, associated with similar histopathological changes.
Based on available literature, it seems that this myxozoan is a novel and previously undescribed species of parasite. The fact that the farmed fish acquired infection of this group of parasite, suggest that infective spores from annelids, have been introduced into the rearing tanks. Whether the histopathology observed is solely due to this infection is unclear at this time. However, the cardiomyopathy observed is likely to cause harm to the fish.