| Cryptosporidium spp.and Enterocytozoon bieneusi are emerging pathogens of infectious diseases,causing diarrhea,decreased appetite,weight loss,growth retardation and other symptoms in humans and animals.Thus,they affect human health and causes serious effect to animal husbandry.Most studies focused on the distribution of Cryptosporidium species and E.bieneusi in intensive managed sheep and cattle,which caused little information available on the distribution of Cryptosporidium species and E.bieneusi in Tibetan sheep and yaks,free-range animals living in a cold,low oxygen and high ultraviolet radition habitat.To improve our knowledge of the distribution of above two pathogens in Tibetan sheep and yaks,350 specimens from Tibetan sheep in six counties and 554 specimens from yaks in five counties were collected in Qinghai Province.All specimens were screened for Cryptosporidium spp.and E.bieneusi by nested PCR(polymerase chain reaction)analysis of the SSU rRNA(small subunit ribosomal RNA)gene and the ribosomal internal transcribed spacer(ITS),respectively followed by sequencing to differentiate the species and genotypes.For Cryptosporidium ubiquitum positive specimens,a-950 bp fragment of the gp60(60 kDa glycoprotein)gene was amplified by nested PCR and sequencing to understand the subtype distribtion.Among the specimens analyzed,43(12.3%)Tibetan sheep and 158(28.5%)yaks were positive for Cryptospordium spp.In Tibetan sheep,Cryptosporidium xiaoi(39/43,90.7%)was the dominant species,followed by C.ubiquitum(4/43,9.3%).All C.ubiquitum derived from Tibetan sheep belonged to the zoonotic subtype family ⅩⅡa.In contrast,several species were identified in yaks:Cryptosporidium andersoni(72/158,45.6%),Cryptosporidium bovis(47/158,29.7%),Cryptosporidium ryanae cattle type(35/158,22.2%),Cryptosporidium ryanae buffalo type(2/158,1.3%),and Cryptosporidium suis-like(2/158,1.3%).The finding of C andersoni as the dominant species in yaks was different from the previous studies where this species was seldom identified in yak specimens.In spite of sharing habitats,Tibetan sheep and yaks are markedly infected with different Cryptosporidium species,suggesting the minimal occurrence of cross-species transmission between the two hosts.In addition,C.ubiquitum,C.andersoni,C.bovis and C.suis-like in Tibetan sheep and yaks were zoonotic species with public health significance.In this study,73(20.9%)Tibetan sheep and 40(7.2%)yaks were positive for E.bieneusi.Three known genotypes were dominant ones in Tibetan sheep,including BEB6(n=31),COS-I(n=25),NESH5(n=11).In addition,five new genotypes were detected in Tibetan sheep,including CHS 17(n=2)and CHS13-CHS16(one each).On the other hand,seven genotypes were identified in yaks,including J(n=19),BEB6(n=7),BEB4(n=7),COS-I(n=2),NESH5(n=1),CHN13(n=3)and CHN14(n=1),with CHN13 and CHN14 belonging to novel genotypes.Three genotypes(BEB6,COS-I and NESH5)were indentified in both Tibetan sheep and yaks in the same counties,indicating the likely cross-species transmission of E.bieneusi between the two hosts.In this study,2 novel genotypes(CHN14 and CHS 17)belonged to zoonotic group 1,and 3 known genotypes(BEB6,BEB4 and J)were reported in humans previously,indicating that Tibetan sheep and yaks are potential reservoirs for human E.bieneusi infection,thus having public health significance.The results of this study improved our knowledge of the distribution of the two pathogens in Tibetan sheep and yaks,and provided basis for preventing transmission of the two pathogens between animals and humans. |
