Pathology and molecular characterization of Leucocytozoon caulleryi from backyard chickens in Khon Kaen Province, Thailand

AIM: The aim of this study was to characterize Leucocytozoon caulleryi from backyard chickens in Khon Kaen Province, Thailand. MATERIALS AND METHODS: Tissue samples were collected from backyard chickens suspected to have leucocytozoonosis and subjected to histopathology examination. The BLAST Tool at NCBI GenBank (Basic Local Alignment Research Tools) (http://www.ncbi.nlm.nih.gov/BLAST) was used to identify the nucleotide sequence of the partial cytochrome c oxidase subunit I (cox I) gene. A Phylogenetic tree for analysis of L. caulleryi was constructed by using MEGA 7.0 software (https://www.megasoftware.net/). RESULTS: The necropsy results revealed the subcutaneous hemorrhages of pectoral muscles, multifocal hemorrhages of the thymus and pectoral muscles, hemorrhage of the proventriculus and peritoneal cavity, and megaloschizonts of the pancreas and intestine, including subcapsular hemorrhages of the liver. Microscopic examination revealed numerous megaloschizonts of Leucocytozoon spp. in the pectoral muscles, intestine, pancreas, and thymus. Molecular analysis of the partial cox I gene showed that the causal agent was closely related to L. caulleryi reported in Japan. CONCLUSION: From these results, L. caulleryi was determined to be the causal agent of leucocytozoonosis and was closely associated with L. caulleryi reported in Japan.