Morphological and molecular detection of myxosporean parasites in freshwater fish in Myanmar

Myxozoans are one of the most important groups of microscopic metazoan parasite, infecting freshwater fish both in the wild and in aquaculture. During the twelve months of the study period (between January and December 2018), a total of 240 fish samples, including 60 Labeo rohita , 60 Puntius chola , 60 Pethia ticto and 60 Systomus sarana, were collected from Yezin Dam, Myanmar. Fish samples were examined under a binocular light microscope for the presence of myxosporean parasites. DNA extracted from infected tissues was conducted for PCR targeting small subunit ribosomal DNA (SSU rDNA) genes of myxosporean. The overall parasite infection rate was 48.8% (117/240) and it was highest (22.1%, 53/240) in the rainy season (June–September). In this study, morphological study revealed that five Myxobolus spp. ( Myxobolus sp. 1, 4–6, and 9) and two Thelohanellus spp. ( Thelohanellus sp. 1 and 2) were found to be infected in the gills (gill filaments) and kidneys, four Myxobolus spp. ( Myxobolus sp. 2, 3, 7 and 8) were infected in the gills and one Myxobolus sp. ( Myxobolus sp. 10) was infected in the kidneys of four studied fish species. Among them, three sequences (LC510617, LC510618 and LC510619) were isolated from detected parasites. The obtained sequences were similar (88.1–98.8%) to those derived from myxosporean parasites deposited in GenBank. This is the first report on molecular information about myxosporean parasites in Myanmar.