LAUSR

Background Yak, a predominant livestock of plateau areas, is known as a host to many parasites. And the genus Entamoeba , the third-common cause of the mortality worldwide from parasitic diseases, was discovered in yaks once. Methods We investigated the distribution and species of Entamoeba spp. from yaks in Qinghai province, northwestern China, by collecting 1027 yak fecal samples. All samples were divided according to seven geographical sites, four seasons, and two age groups of yaks. After extracting DNA, polymerase chain reaction (PCR) was performed to amplify the 18S rRNA gene, and sequences were analyzed with phylogenetic method. Results We observed an overall Entamoeba positive rate of 36.32% (373/1027) in yaks from Qinghai province. The common species included Entamoeba bovis (284/373), Entamoeba sp. MG107/BEL (79/373), Entamoeba sp. ribosomal lineage (RL) two (8/373), and Entamoeba sp. RL9 (2/373) . According to the result of statistical analysis, Entamoeba infection rate was the highest in summer and significantly differed from that observed during other seasons ( P  < 0.05). The yaks from Golog had the highest prevalence of Entamoeba among all geographical origins in Qinghai province ( P  < 0.05). However, no significant difference was observed ( P  > 0.05) among different age groups, as evident from a positive rate of 39.58% in ≤ 6-month and 36.16% in > 6-month yaks. Conclusion These results indicate the prevalence and predominant species of Entamoeba in yaks. To our knowledge, this is the first study to report E. bovis , Entamoeba sp. RL2, and Entamoeba sp. RL9 in Chinese yaks.