ABSTRACT
Objective To identify the genetic variation and possible sources of Thelazia callipaeda isolates collected from pa-tients in Zunyi City,Guizhou Province. Methods Seven cases of T. callipaeda infection in Zunyi City,2016 were verified, and DNA(s)were extracted from the T. callipaeda's body collected from the thelaziasis patients. A mitochondrial COX1 frag-ment was amplified and sequenced. The sequence alignment and phylogenetical analysis were performed to compare the genetic variation of the gene sequence with the homologous sequences downloaded from Genebank. Results COX1 genes of T. callipae-da were differed among the samples from the seven cases,which had low variation. Conclusion Zunyi City is a new area with endemic of thelaziasis. The isolates from Zunyi City include either Asian origin or European origin of T. callipaeda. Moreover,at least four haplotypes are identified among the seven isolates.