First report of Blastocystis infections in cattle in China.

Blastocystis is one of the most common intestinal protists of humans and can also infect a variety of other mammals and birds. Blastocystis infections and subtype distribution in cattle have been documented, while nothing is known about those in China. Herein, a total of 526 dairy cattle from northeast China were sampled and investigated for the prevalence and genetic characteristics of Blastocystis and the potential role of bovine animals in zoonotic transmission of Blastocystis. The parasite was identified in 54 (10.3%) fecal specimens by nested PCR and DNA sequencing of the small subunit ribosomal RNA gene. Sequence analysis enabled identification of four Blastocystis subtypes (STs). Among those, subtype ST10 (75.9%, 41/54) has the highest frequency, followed by ST14 (18.5%, 10/54), ST4 (3.7%, 2/54), and ST5 (1.9%, 1/54). High prevalence and widespread distribution of ST10 and ST14 in cattle observed herein, together with analysis of their host distribution patterns in earlier studies, indicated some host-adapted potential in the two subtypes. The identification of human-pathogenic subtypes ST4 and ST5 might imply a potential zoonotic risk of cattle origin. This is the first study exploring the prevalence and genetic characteristics of Blastocystis in cattle in China. The host range of subtype ST4 was extended. The findings of this study should be helpful for a better understanding of the epidemiology and public health potential of Blastocystis.