Mitochondrial genomic markers confirm the presence of the camel strain (G6 genotype) of Echinococcus granulosus in north-western China

Twenty-eight isolates of E. granulosus, collected from humans at surgery, and a range of intermediate hosts, including sheep, cattle and camels from abattoirs in North and South Xinjiang Uygur Autonomous Region, People's Republic of China, were analysed for DNA sequence variation within regions of the mitochondrial cytochrome c oxidase I (COI) and NADH dehydrogenase subunit I (NDI) genes. The isolates were categorized into 2 distinct and uniform genotypic groupings, based on the sequences obtained, and the data clearly indicated that the camel/dog strain (G6 genotype) of E. granulosus as well as the cosmopolitan, common sheep strain (G1 genotype) occur in north Xinjiang. The presence of the camel strain has thus been confirmed in Xinjiang but it is evident from this and a previous molecular genetic survey of E. granulosus isolates from north-western China that the common sheep strain is the most predominant in the region. From the public health perspective, the majority of infected livestock will act as reservoirs of human infection there. During the course of the study, a polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay, based on the NDI sequence variation, was developed that allows rapid discrimination of the G1 and G6 genotypes.