Molecular characterization of muscle infecting Myxobolus sp. causing outbreak in Labeo rohita, Rohu: First report from Andaman Islands

Among the myxozoan parasites, the genus Myxobolus is considered as the emerging parasite in freshwater aquaculture. In the present study, a disease outbreak associated with mass mortality was investigated in a carp farm located at North and Middle Andaman district of Andaman and Nicobar Islands. The affected rohu fry exhibited the clinical signs such as lethargic movement, dark body colouration, loss of appetite, excess mucus secretion, 1-2 mm multifocal white nodules on the body surface and skeletal deformities including spinal curvatures. Molecular characterization using 18S rRNA along with clinical signs identified the causative agent as muscle infecting Myxobolus sp. (GenBank accession number MK128509) which showed 95.45% identity with Myxobolus musculi and 95.23% identity with Myxobolus pseudodispar. Genetic distance and phylogenetic tree analysis were performed to elucidate the relationship between the Myxobolus sp. obtained in the present study and the members of other congeners. This investigation serves as the first report of Myxobolus sp. outbreak from Andaman and Nicobar Islands and also reiterates the need for implementation of strict biosecurity measures to preserve the freshwater aquatic fauna of these Islands.