Molecular characteristics and zoonotic potential of enteric protozoans in domestic small ruminants in Heilongjiang Province, Northeast China

<i>Cryptosporidium</i> spp., <i>Giardia duodenalis</i>, <i>Enterocytozoon bieneusi</i>, and <i>Blastocystis</i> sp. are four common zoonotic intestinal protozoa, that cause frequent foodborne and waterborne outbreaks worldwide. Despite their public health importance, epidemiological data remain scarce from Heilongjiang Province in China. Fecal samples were collected from 845 sheep and 166 goats across 13 regions of Heilongjiang Province, Northeast China. PCR-based methods were used to detect these pathogens and PCR products were sequenced to determine the species/genotypes. The overall infection rates for <i>Cryptosporidium</i> spp., <i>G. duodenalis</i>, <i>E. bieneusi</i>, and <i>Blastocystis</i> sp. were 4.15 % (42/1011), 2.67 % (27/1011), 12.15 % (127/1011), and 3.56 % (36/1011), respectively. The mixed infections with two or more protozoa occurred in 2.97 % (30/1011). The geographic location was a significant risk factor for the prevalence of <i>Cryptosporidium</i> spp., <i>E. bieneusi</i>, and <i>Blastocystis</i> sp. in domestic small ruminants. Four <i>Cryptosporidium</i> genotypes (<i>C. xiaoi</i>, <i>C. ubiquitum</i>, <i>C. bovis</i>, <i>C. andersoni</i>), seven <i>E. bieneusi</i> genotypes (BEB6, COS-I, CHS8, CHS7, CHG1, CHG3, J), two <i>G. duodenalis</i> assemblages (assemblage E, assemblage A), and six <i>Blastocystis</i> subtypes (ST10, ST14, ST26, ST5, ST15, ST30) were identified. This study provides critical data for developing control strategies with significant implications for zoonotic risk assessment in Heilongjiang Province.