Studies On Prevalence And Genotyping Of Blastocystis In Pigs In Some Regions Of Shaanxi Province

Blastocystis is a potentially pathogenic single-celled protozoan which inhabits the intestines of humans and animals,with a worldwide distribution.Its hosts include humans and nearly all mammals,and it is more prevalent in poor and backward areas.In general,different symptoms of Blastocystis infection are observed in clinic,and symptoms,such as diarrhea,vomiting and nausea could be presented in severe infections.Recent studies abroad have shown that pigs are an important reservoir of Blastocystis with high prevalence and wide zoonotic subtypes.However,limited studies of Blastocystis prevalence in pigs were available for Blastocystis in China.Therefore,the present study firstly investigated the prevalence of Blastocystis in pigs of different age groups from some areas of Shaanxi province,and Blastocystis the subtypes of these pathogens were also identified.From October 2016 to March 2017,a total of 560 pig fecal samples were collected from five regions in Shaanxi province and the genomic DNA samples of them were extracted using the commercial kit.Then,PCR technology targeting small subunit ribosomal RNA(SSU rRNA)of Blastocystis was applied.The results showed that an approximately 600 bp band was detected in 432 samples,but only 419 of them were positive for Blastocystis infection by sequence analysis,with a total prevalence of 74.8%(419/560).Significant differences in prevalence were found among five examined regions(P< 0.05),with the highest in Lintong(89.2%),followed by Yuyang of Yulin(83.5%),Qishan of Baoji(77%),and Mianxian of Hanzhong(68%).The lowest prevalence was detected in Zhouzhi(60.8%).Moreover,significant differences in prevalence were also observed among four age groups.The prevalence in pigs aged 4-6 months was significantly higher than in other age groups,and the lowest was detected in pigs of 1-2 months.However,no statistically significant differences in Blastocystis prevalence were found between sows and boars.To identify the genotyps of Blastocystis in pigs from partial areas of Shaanxi,the phylogenetic tree was constructed based on the SSU rRNA sequences.Four subtypes were identified in these pigs,including three zoonotic(ST1,ST3,ST5)and one animal-specific subtypes(ST10).Of them,the ST5(94.7%,397/419)was the predominant subtype widely distributed in pigs of all age groups and all examined areas.The second subtype was ST1 that which was found in suckling piglets(< 25 days)and weaned pigs(1-6 months)of all farms expect Yulin.However,the ST3 subtype was only detected in pigs of less than 4 months from Hanzhong and Lintong.In addition,the ST10 subtype was firstly reported to infect pigs.In summary,this study revealed the high prevalence of Blastocystis infection in pigs in some regions of Shaanxi province and indicated significant differences in prevalence among different age groups from five investigated regions.Zoonotic subtypes were found in all pig farms and the ST5 was the predominant subtype.These results indicated that the prevalence of Blastocystis in pigs was highly serious and comprehensive prevention measures should be implemented to control Blastocystis infection in pigs in Shaanxi province.