牛十二指肠贾第虫的分子流行病学研究进展

doi:10.11843/j.issn.0366-6964.2021.02.003

摘要/Abstract

摘要： 贾第虫是一类在全球范围内广泛分布的寄生虫，包括7个虫种。其中的十二指肠贾第虫（Giardia duodenalis）是一种重要的肠道寄生虫，能感染人和大多数哺乳动物，可引起腹泻、营养不良和体重减轻等症状。分子分型工具的发展促进了贾第虫检测、基因分型和溯源的发展，大大改变了人们对贾第虫人兽共患潜力的理解。利用分子分型工具可将十二指肠贾第虫分为8种集聚体（A~H），8种集聚体的宿主范围都存在差异，其中，集聚体A和B是人兽共患型。牛是十二指肠贾第虫的重要宿主，但目前对牛十二指肠贾第虫病的分子流行病学认识不够，其公共卫生意义也一直被忽视。本文汇总了国内牛十二指肠贾第虫的分子流行病学调查结果。结果发现，我国牛十二指肠贾第虫的感染是普遍存在的，其中，集聚体E为优势集聚体，集聚体A和B呈散发流行。近年来，一些国家出现了集聚体E感染人的报道，同时，集聚体A在牛中的感染率有上升的迹象，牛十二指肠贾第虫的人兽共患潜力正在逐步得到认识。

关键词: 十二指肠贾第虫, 牛, 分子流行病学, 人兽共患潜力

Abstract: Giardia spp. are globally widespread, including seven species. One of the species, Giardia duodenalis, is an important intestinal parasite in humans and other mammals. It causes diarrhea, malnutrition, weight loss and other clinical manifestations. Molecular diagnostic tools have been developed for the detection, genotyping, and tracking of G. duodenalis, and the use of molecular diagnostic tools has significantly changed our understanding of the zoonotic potential of the parasite. G. duodenalis can be divided into 8 assemblages (A-H) using molecular typing tools. These assemblages differ significantly in host ranges, with assemblages A and B being identified as zoonosis. Cattle are commonly infected with G. duodenalis, but the current understanding of giardiasis is insufficient and the influence on public health has always been neglected. This article summarizes recent developments in the molecular epidemiology of G. duodenalis from cattle in China. It shows that the infections of G. duodenalis are widespread in China. In the distribution of G. duodenalis genotypes, assemblage E predominates while assemblages A and B occur sporadically. As assemblage E has recently been found in humans in several other countries and the occurrence of assemblage A in cattle has shown an increase in recent years, the zoonotic potential of G. duodenalis from cattle is gradually being recognized.

Key words: Giardia duodenalis, cattle, molecular epidemiology, zoonotic potential

中图分类号:

S852.72

蔡伟龙, 李娜, 冯耀宇, 肖立华. 牛十二指肠贾第虫的分子流行病学研究进展[J]. 畜牧兽医学报, 2021, 52(2): 300-310.

CAI Weilong, LI Na, FENG Yaoyu, XIAO Lihua. Advances in Molecular Epidemiology of Giardia duodenalis from Cattle in China[J]. Acta Veterinaria et Zootechnica Sinica, 2021, 52(2): 300-310.

参考文献 98

[1]	ACOSTA-VIRGEN K, CHÁVEZ-MUNGUÍA B, TALAMÁS-LARA D, et al. Giardia lamblia:identification of peroxisomal-like proteins[J]. Exp Parasitol, 2018, 191:36-43.
[2]	ANKARKLEV J, JERLSTRÖM-HULTQVIST J, RINGQVIST E, et al. Behind the smile:cell biology and disease mechanisms of Giardia species[J]. Nat Rev Microbiol, 2010, 8(6):413-422.
[3]	CARRANZA P G, LUJAN H D. New insights regarding the biology of Giardia lamblia[J]. Microbes Infect, 2010, 12(1):71-80.
[4]	FENG Y Y, XIAO L H. Zoonotic potential and molecular epidemiology of Giardia species and giardiasis[J]. Clin Microbiol Rev, 2011, 24(1):110-140.
[5]	RYAN U, ZAHEDI A. Molecular epidemiology of giardiasis from a veterinary perspective[J]. Adv Parasitol, 2019, 106:209-254.
[6]	EINARSSON E, MA'AYEH S, SVÄRD S G. An up-date on Giardia and giardiasis[J]. Curr Opin Microbiol, 2016, 34:47-52.
[7]	武省, 李国清. 蓝氏贾第虫致病机制的研究进展[J]. 中国动物传染病学报, 2015, 23(1):64-70.WU S, LI G Q. Research progress on the pathogenic mechanism of Giardia lamblia[J]. Chinese Journal of Animal Infectious Diseases, 2015, 23(1):64-70. (in Chinese)
[8]	HELLARD M E, SINCLAIR M I, HOGG G G, et al. Prevalence of enteric pathogens among community based asymptomatic individuals[J]. J Gastroenterol Hepatol, 2000, 15(3):290-293.
[9]	ESCOBEDO A A, ALMIRALL P, ROBERTSON L J, et al. Giardiasis:the ever-present threat of a neglected disease[J]. Infect Disord Drug Targets, 2010, 10(5):329-348.
[10]	KARANIS P, KOURENTI C, SMITH H. Waterborne transmission of protozoan parasites:a worldwide review of outbreaks and lessons learnt[J]. J Water Health, 2007, 5(1):1-38.
[11]	THOMPSON R C A. The zoonotic significance and molecular epidemiology of Giardia and giardiasis[J]. Vet Parasitol, 2004, 126(1-2):15-35.
[12]	徐宁, 尹建海, 沈玉娟, 等. 隐孢子虫和蓝氏贾第鞭毛虫分子流行病学研究进展[J]. 中国寄生虫学与寄生虫病杂志, 2018, 36(6):661-665, 672.XU N, YIN J H, SHEN Y J, et al. Advances in molecular epidemiology of Cryptosporidium and Giardia lamblia[J]. Chinese Journal of Parasitology and Parasitic Diseases, 2018, 36(6):661-665, 672. (in Chinese)
[13]	WANG L, XIAO L H, DUAN L P, et al. Concurrent infections of Giardia duodenalis, Enterocytozoon bieneusi, and Clostridium difficile in children during a cryptosporidiosis outbreak in a pediatric hospital in China[J]. PLoS Negl Trop Dis, 2013, 7(9):e2437.
[14]	LV S, TIAN L G, LIU Q, et al. Water-related parasitic diseases in China[J]. Int J Environ Res Public Health, 2013, 10(5):1977-2016.
[15]	LI J Q, WANG H Y, WANG R J, et al. Giardia duodenalis infections in humans and other animals in China[J]. Front Microbiol, 2017, 8:2004.
[16]	CACCIÒ S M, LALLE M, SVÄRD S G. Host specificity in the Giardia duodenalis species complex[J]. Infect Genet Evol, 2018, 66:335-345.
[17]	RYAN U, CACCIÒ S M. Zoonotic potential of Giardia[J]. Int J Parasitol, 2013, 43(12-13):943-956.
[18]	SANTIN M. Cryptosporidium and Giardia in ruminants[J]. Vet Clin North Am Food Anim Pract, 2020, 36(1):223-238.
[19]	LIU A Q, YANG F K, SHEN Y J, et al. Genetic analysis of the Gdh and Bg genes of animal-derived Giardia duodenalis isolates in Northeastern China and evaluation of zoonotic transmission potential[J]. PLoS One, 2014, 9(4):e95291.
[20]	KIANI-SALMI N, FATTAHI-BAFGHI A, ASTANI A, et al. Molecular typing of Giardia duodenalis in cattle, sheep and goats in an arid area of central Iran[J]. Infect Genet Evol, 2019, 75:104021.
[21]	MORRISON H G, MCARTHUR A G, GILLIN F D, et al. Genomic minimalism in the early diverging intestinal parasite Giardia lamblia[J]. Science, 2007, 317(5846):1921-1926.
[22]	ERLANDSEN S L, BEMRICK W J. SEM evidence for a new species, Giardia psittaci[J]. J Parasitol, 1987, 73(3):623-629.
[23]	张静, 苏艳, 白光彦, 等. 东北地区部分犊牛感染贾第虫的基因型及基因亚型分析[J]. 中国兽医学报, 2012, 32(11):1679-1682, 1707.ZHANG J, SU Y, BAI G Y, et al. Genotype in dentification of Giardia from cattle in part areas of northeast China[J]. Chinese Journal of Veterinary Science, 2012, 32(11):1679-1682, 1707. (in Chinese)
[24]	CACCIÒ S M, BECK R, LALLE M, et al. Multilocus genotyping of Giardia duodenalis reveals striking differences between assemblages A and B[J]. Int J Parasitol, 2008, 38(13):1523-1531.
[25]	MOON D J, MASEKO B C, IHUNWO A O, et al. Distribution and morphology of catecholaminergic and serotonergic neurons in the brain of the highveld gerbil, Tatera brantsii[J]. J Chem Neuroanat, 2007, 34(3-4):134-144.
[26]	JULIEN D A, SARGEANT J M, GUY R A, et al. Prevalence and genetic characterization of Giardia spp. and Cryptosporidium spp. in dogs in Iqaluit, Nunavut, Canada[J]. Zoonoses Public Health, 2019, 66(7):813-825.
[27]	ABDEL-MOEIN K A, SAEED H. The zoonotic potential of Giardia intestinalis assemblage E in rural settings[J]. Parasitol Res, 2016, 115(8):3197-3202.
[28]	LI W C, LIU X C, GU Y F, et al. Prevalence of Cryptosporidium, Giardia, Blastocystis, and trichomonads in domestic cats in East China[J]. J Vet Med Sci, 2019, 81(6):890-896.
[29]	LI J Y, DAN X Y, ZHU K X, et al. Genetic characterization of Cryptosporidium spp. and Giardia duodenalis in dogs and cats in Guangdong, China[J]. Parasit Vectors, 2019, 12(1):571.
[30]	WIELINGA C M, THOMPSON R C A. Comparative evaluation of Giardia duodenalis sequence data[J]. Parasitology, 2007, 134(12):1795-1821.
[31]	XIAO L H, FENG Y Y. Molecular epidemiologic tools for waterborne pathogens Cryptosporidium spp. and Giardia duodenalis[J]. Food Waterborne Parasitol, 2017, 8-9:14-32.
[32]	ANKARKLEV J, SVÄRD S G, LEBBAD M. Allelic sequence heterozygosity in single Giardia parasites[J]. BMC Microbiol, 2012, 12:65.
[33]	TRAUB R J, MONIS P T, ROBERTSON I, et al. Epidemiological and molecular evidence supports the zoonotic transmission of Giardia among humans and dogs living in the same community[J]. Parasitology, 2004, 128(3):253-262.
[34]	CHOY S H, MAHDY M A K, AL-MEKHLAFI H M, et al. Population expansion and gene flow in Giardia duodenalis as revealed by triosephosphate isomerase gene[J]. Parasit Vectors, 2015, 8:454.
[35]	DURIGAN M, CIAMPI-GUILLARDI M, RODRIGUES R C A, et al. Population genetic analysis of Giardia duodenalis:genetic diversity and haplotype sharing between clinical and environmental sources[J]. Microbiologyopen, 2017, 6(2):e00424.
[36]	GABÍN-GARCÍA L B, BARTOLOMÉ C, ABAL-FABEIRO J L, et al. Strong genetic structure revealed by multilocus patterns of variation in Giardia duodenalis isolates of patients from Galicia (NW-Iberian Peninsula)[J]. Infect Genet Evol, 2017, 48:131-141.
[37]	FENG Y Y, GONG X Q, ZHU K X, et al. Prevalence and genotypic identification of Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in pre-weaned dairy calves in Guangdong, China[J]. Parasit Vectors, 2019, 12(1):41.
[38]	ABEYWARDENA H, JEX A R, GASSER R B. A perspective on Cryptosporidium and Giardia, with an emphasis on bovines and recent epidemiological findings[J]. Adv Parasitol, 2015, 88:243-301.
[39]	BARTLEY P M, ROEHE B K, THOMSON S, et al. Detection of potentially human infectious assemblages of Giardia duodenalis in fecal samples from beef and dairy cattle in Scotland[J]. Parasitology, 2019, 146(9):1123-1130.
[40]	MAHATO M K, SINGH D K, RANA H B, et al. Prevalence and risk factors associated with Giardia duodenalis infection in dairy cattle of Chitwan, Nepal[J]. J Parasit Dis, 2018, 42(1):122-126.
[41]	CACCIÒ S M, RYAN U. Molecular epidemiology of giardiasis[J]. Mol Biochem Parasitol, 2008, 160(2):75-80.
[42]	MINETTI C, TAWEENAN W, HOGG R, et al. Occurrence and diversity of Giardia duodenalis assemblages in livestock in the UK[J]. Transbound Emerg Dis, 2014, 61(6):e60-e67.
[43]	QI M, WANG H, JING B, et al. Prevalence and multilocus genotyping of Giardia duodenalis in dairy calves in Xinjiang, Northwestern China[J]. Parasit Vectors, 2016, 9(1):546.
[44]	JIAN Y N, ZHANG X Y, LI X P, et al. Prevalence and molecular characterization of Giardia duodenalis in cattle and sheep from the Qinghai-Tibetan Plateau area (QTPA), Northwestern China[J]. Vet Parasitol, 2018, 250:40-44.
[45]	ZHANG Q X, ZHANG Z C, AI S T, et al. Cryptosporidium spp., Enterocytozoon bieneusi, and Giardia duodenalis from animal sources in the Qinghai-Tibetan Plateau area (QTPA) in China[J]. Comp Immunol Microbiol Infect Dis, 2019, 67:101346.
[46]	WU Y Y, CHANG Y K, ZHANG X Q, et al. Molecular characterization and distribution of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi from yaks in Tibet, China[J]. BMC Vet Res, 2019, 15(1):417.
[47]	QI M, CAI J Z, WANG R J, et al. Molecular characterization of Cryptosporidium spp. and Giardia duodenalis from yaks in the central western region of China[J]. BMC Microbiol, 2015, 15:108.
[48]	JIN Y, FEI J L, CAI J Z, et al. Multilocus genotyping of Giardia duodenalis in Tibetan sheep and yaks in Qinghai, China[J]. Vet Parasitol, 2017, 247:70-76.
[49]	WANG G P, WANG G H, LI X P, et al. Prevalence and molecular characterization of Cryptosporidium spp. and Giardia duodenalis in 1-2-month-old highland yaks in Qinghai province, China[J]. Parasitol Res, 2018, 117(6):1793-1800.
[50]	WANG G H, WANG G P, LI X P, et al. Detection of Giardia duodenalis assemblage E infections at the Tibetan Plateau area:yaks are suitable hosts[J]. Acta Trop, 2017, 169:157-162.
[51]	MA L Q, SOTIRIADOU I, CAI Q G, et al. Detection of Cryptosporidium and Giardia in agricultural and water environments in the Qinghai area of China by IFT and PCR[J]. Parasitol Res, 2014, 113(9):3177-3184.
[52]	王光华, 李秀萍, 王戈平, 等. 青海牦牛源贾第虫的鉴定及分子特征分析[J]. 动物医学进展, 2016, 37(8):15-18.WANG G H, LI X P, WANG G P, et al. Identification and molecular characterization of yak-derived Giardia species in Qinghai province[J]. Progress in Veterinary Medicine, 2016, 37(8):15-18. (in Chinese)
[53]	王光华, 王戈平, 李秀萍, 等. 青海省海北地区牦牛源贾第虫检测与基因型分析[J]. 动物医学进展, 2016, 37(7):30-33.WANG G H, WANG G P, LI X P, et al. Detection and genotyping of Giardia isolates from yaks in Haibei area of Qinghai province[J]. Progress in Veterinary Medicine, 2016, 37(7):30-33. (in Chinese)
[54]	ZHANG X X, TAN Q D, ZHAO G H, et al. Prevalence, risk factors and multilocus genotyping of Giardia intestinalis in dairy cattle, Northwest China[J]. J Eukaryot Microbiol, 2016, 63(4):498-504.
[55]	SONG G Y, QIN S Y, ZHAO G H, et al. Molecular characterization of Giardia duodenalis from white yaks in China[J]. Acta Parasitol, 2016, 61(2):397-400.
[56]	曹建科, 常艳凯, 毋亚运, 等. 甘肃地区奶牛肠道寄生虫感染情况调查[J]. 畜牧与兽医, 2017, 49(7):109-113.CAO J K, CHANG Y K, WU Y Y, et al. Investigation of intestinal parasite infections in dairy cattle in Gansu province[J]. Animal Husbandry & Veterinary Medicine, 2017, 49(7):109-113. (in Chinese)
[57]	HUANG J Y, YUE D Y, QI M. Prevalence and molecular characterization of Cryptosporidium spp. and Giardia duodenalis in dairy cattle in Ningxia, northwestern China[J]. BMC Vet Res, 2014, 10:292.
[58]	DAN J M, ZHANG X P, REN Z H, et al. Occurrence and multilocus genotyping of Giardia duodenalis from post-weaned dairy calves in Sichuan province, China[J]. PLoS One, 2019, 14(11):e0224627.
[59]	ZHONG Z J, DAN J M, YAN G W, et al. Occurrence and genotyping of Giardia duodenalis and Cryptosporidium in pre-weaned dairy calves in central Sichuan province, China[J]. Parasite, 2018, 25:45.
[60]	WANG X T, WANG R J, REN G J, et al. Multilocus genotyping of Giardia duodenalis and Enterocytozoon bieneusi in dairy and native beef (Qinchuan) calves in Shaanxi province, northwestern China[J]. Parasitol Res, 2016, 115(3):1355-1361.
[61]	LI F H, WANG H Y, ZHANG Z J, et al. Prevalence and molecular characterization of Cryptosporidium spp. and Giardia duodenalis in dairy cattle in Beijing, China[J]. Vet Parasitol, 2016, 219:61-65.
[62]	HU S H, LIU Z Z, YAN F B, et al. Zoonotic and host-adapted genotypes of Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in dairy cattle in Hebei and Tianjin, China[J]. Vet Parasitol, 2017, 248:68-73.
[63]	WANG H, ZHAO G, CHEN G, et al. Multilocus genotyping of Giardia duodenalis in dairy cattle in Henan, China[J]. PLoS One, 2014, 9(6):e100453.
[64]	陈功义, 李爱心, 李丽, 等. 河南省中牟地区奶牛隐孢子虫、贾第虫病感染情况调查及基因型鉴定[J]. 中国奶牛, 2015(5):35-38.CHEN G Y, LI A X, LI L, et al. Epidemiological investigation and molecular characteristics of Giardia and Cryptosporidium in Zhongmou county, Henan[J]. China Dairy Cattle, 2015(5):35-38. (in Chinese)
[65]	王臣荣, 张振杰, 李俊强, 等. 进口奶牛十二指肠贾第虫感染情况及其多位点基因序列研究[J]. 畜牧兽医学报, 2016, 47(1):165-171.WANG C R, ZHANG Z J, LI J Q, et al. The investigation of infection and multilocus sequence of Giardia duodenalis in dairy cattle from an imported farm[J]. Acta Veterinaria et Zootechnica Sinica, 2016, 47(1):165-171. (in Chinese)
[66]	赵金凤, 王海燕, 齐萌, 等. 开封地区奶牛十二指肠贾第虫流行情况及多位点基因分型的研究[J]. 中国兽医科学, 2016, 46(4):496-501.ZHAO J F, WANG H Y, QI M, et al. Prevalence and multilocus genotyping of Giardia duodenalis in dairy cattle in Kaifeng, China[J]. Chinese Veterinary Science, 2016, 46(4):496-501. (in Chinese)
[67]	陈功义, 王海燕, 李丽, 等. 奶牛肠道寄生虫感染情况调查及两种主要原虫病的种类基因型鉴定[J]. 中国兽医杂志, 2015, 51(3):47-49.CHEN G Y, WANG H Y, LI L, et al. Investigation of intestinal parasitic infection in cows and genotype identification of two major protozoa diseases[J]. Chinese Journal of Veterinary Medicine, 2015, 51(3):47-49. (in Chinese)
[68]	FAN Y Y, WANG T, KOEHLER A V, et al. Molecular investigation of Cryptosporidium and Giardia in pre- and post-weaned calves in Hubei province, China[J]. Parasit Vectors, 2017, 10(1):519.
[69]	WANG R, LI N, JIANG W, et al. Infection patterns, clinical significance, and genetic characteristics of Enterocytozoon bieneusi and Giardia duodenalis in dairy cattle in Jiangsu, China[J]. Parasitol Res, 2019, 118(10):3053-3060.
[70]	WANG X L, CAI M, JIANG W, et al. High genetic diversity of Giardia duodenalis assemblage E in pre-weaned dairy calves in Shanghai, China, revealed by multilocus genotyping[J]. Parasitol Res, 2017, 116(8):2101-2110.
[71]	CUI Z H, WANG L Y, CAO L T, et al. Genetic characteristics and geographic segregation of Giardia duodenalis in dairy cattle from Guangdong province, southern China[J]. Infect Genet Evol, 2018, 66:95-100.
[72]	HSU B M, WUN H Y, HSU P C. Prevalence and genotyping of Giardia in husbandry systems in Taiwan[J]. Parasitol Res, 2007, 101(2):275-280.
[73]	LAM H Y P, CHEN T T W, TSENG Y C, et al. Detection and genotyping of Giardia duodenalis from cattle and pigs in Hualien country, Eastern Taiwan[OL/J]. J Microbiol Immunol Infect, 2020. (2020-05-28)[2020-07-10]. https://www.sciencedirect.com/science/article/pii/S1684118220301237.
[74]	LIU G, SU Y, ZHOU M J, et al. Prevalence and molecular characterization of Giardia duodenalis isolates from dairy cattle in northeast China[J]. Exp Parasitol, 2015, 154:20-24.
[75]	LIU A Q, ZHANG X Y, ZHANG L X, et al. Occurrence of bovine giardiasis and endemic genetic characterization of Giardia duodenalis isolates in Heilongjiang Province, in the Northeast of China[J]. Parasitol Res, 2012, 111(2):655-661.
[76]	THOMPSON R C A, PALMER C S, O'HANDLEY R. The public health and clinical significance of Giardia and Cryptosporidium in domestic animals[J]. Vet J, 2008, 177(1):18-25.
[77]	LIU H, SHEN Y J, YIN J H, et al. Prevalence and genetic characterization of Cryptosporidium, Enterocytozoon, Giardia and Cyclospora in diarrheal outpatients in China[J]. BMC Infect Dis, 2014, 14:25.
[78]	SOLIMAN R H, FUENTES I, RUBIO J M. Identification of a novel Assemblage B subgenotype and a zoonotic Assemblage C in human isolates of Giardia intestinalis in Egypt[J]. Parasitol Int, 2011, 60(4):507-511.
[79]	ŠTRKOLCOVÁ G, MAĎAR M, HINNEY B, et al. Dog's genotype of Giardia duodenalis in human:first evidence in Europe[J]. Acta Parasitol, 2015, 60(4):796-799.
[80]	BROGLIA A, WEITZEL T, HARMS G, et al. Molecular typing of Giardia duodenalis isolates from German travellers[J]. Parasitol Res, 2013, 112(10):3449-3456.
[81]	GELANEW T, LALLE M, HAILU A, et al. Molecular characterization of human isolates of Giardia duodenalis from Ethiopia[J]. Acta Trop, 2007, 102(2):92-99.
[82]	FANTINATTI M, BELLO A R, FERNANDES O, et al. Identification of Giardia lamblia assemblage E in humans points to a new anthropozoonotic cycle[J]. J Infect Dis, 2016, 214(8):1256-1259.
[83]	ZAHEDI A, FIELD D, RYAN U. Molecular typing of Giardia duodenalis in humans in Queensland-first report of Assemblage E[J]. Parasitology, 2017, 144(9):1154-1161.
[84]	ROBERTSON L J, FORBERG T, HERMANSEN L, et al. Giardia duodenalis cysts isolated from wild moose and reindeer in Norway:genetic characterization by PCR-rflp and sequence analysis at two genes[J]. J Wildl Dis, 2007, 43(4):576-585.
[85]	UEHLINGER F D, BARKEMA H W, DIXON B R, et al. Giardia duodenalis and Cryptosporidium spp. in a veterinary college bovine teaching herd[J]. Vet Parasitol, 2006, 142(3-4):231-237.
[86]	SANTÍN M, TROUT J M, FAYER R. A longitudinal study of Giardia duodenalis genotypes in dairy cows from birth to 2 years of age[J]. Vet Parasitol, 2009, 162(1-2):40-45.
[87]	BECHER K A, ROBERTSON I D, FRASER D M, et al. Molecular epidemiology of Giardia and Cryptosporidium infections in dairy calves originating from three sources in Western Australia[J]. Vet Parasitol, 2004, 123(1-2):1-9.
[88]	YODER J S, HARRAL C, BEACH M J, et al. Giardiasis surveillance-United States, 2006-2008[J]. MMWR Surveill Summ, 2010, 59(6):15-25.
[89]	TONANI K A A, PADULA J A, JULIĀO F C, et al. Persistence of Giardia, Cryptosporidium, Rotavirus, and Adenovirus in treated sewage in São Paulo state, Brazil[J]. J Parasitol, 2013, 99(6):1144-1147.
[90]	ADAM R D. Biology of Giardia lamblia[J]. Clin Microbiol Rev, 2001, 14(3):447-475.
[91]	RYAN U, HIJJAWI N, FENG Y Y, et al. Giardia:an under-reported foodborne parasite[J]. Int J Parasitol, 2019, 49(1):1-11.
[92]	OATES S C, MILLER M A, HARDIN D, et al. Prevalence, environmental loading, and molecular characterization of Cryptosporidium and Giardia isolates from domestic and wild animals along the Central California Coast[J]. Appl Environ Microbiol, 2012, 78(24):8762-8772.
[93]	HOAR B R, PAUL R R, SIEMBIEDA J, et al. Giardia duodenalis in feedlot cattle from the central and western United States[J]. BMC Vet Res, 2009, 5:37.
[94]	CAMA V A, MATHISON B A. Infections by intestinal Coccidia and Giardia duodenalis[J]. Clin Lab Med, 2015, 35(2):423-444.
[95]	SOARES R, TASCA T. Giardiasis:an update review on sensitivity and specificity of methods for laboratorial diagnosis[J]. J Microbiol Methods, 2016, 129:98-102.
[96]	HIJJAWI N, YANG R C, HATMAL M, et al. Comparison of ELISA, nested PCR and sequencing and a novel qPCR for detection of Giardia isolates from Jordan[J]. Exp Parasitol, 2018, 185:23-28.
[97]	XIAO L H, FAYER R. Molecular characterisation of species and genotypes of Cryptosporidium and Giardia and assessment of zoonotic transmission[J]. Int J Parasitol, 2008, 38(11):1239-1255.
[98]	CACCIÒ S M, THOMPSON R C A, MCLAUCHLIN J, et al. Unravelling Cryptosporidium and Giardia epidemiology[J]. Trends Parasitol, 2005, 21(9):430-437.