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

为了解进口奶牛十二指肠贾第虫感染情况及其集聚体和基因亚型分布特征,作者基于SSU rRNA、tpi、gdh和bg基因位点对奶牛十二指肠贾第虫进行PCR检测。结果如下:基于SSU rRNA基因位点进行PCR检测,奶牛十二指肠贾第虫感染率为9.5%(48/507),48份阳性样品均为十二指肠贾第虫集聚体E;断奶后犊牛感染率最高(20.70%),不同年龄段奶牛十二指肠贾第虫感染率统计学差异极显著(P0.01)。基于tpi、gdh和bg基因位点分别扩增出48份阳性样品中19、28和34个,1份在tpi基因位点呈集聚体A和E混合感染。多位点基因序列分析和种系进化树分析结果显示,该场进口奶牛应为引进后感染十二指肠贾第虫。研究表明进口成年奶牛不易携带人兽共患十二指肠贾第虫,引种场奶牛传播人兽共患十二指肠贾第虫风险较低。     

长春狐狸、貉和家兔养殖场十二指肠贾第虫基因型分析

为了解长春地区狐狸、貉和家兔养殖场的十二指肠贾第虫感染情况,基于十二指肠贾第虫GDH基因位点分别设计2对引物,对养殖场的120份狐狸粪便样品、60份貉粪便样品和148份家兔粪便样品十二指肠贾第虫进行检测和基因型分析。结果表明,在来自狐狸的粪便中检测出阳性样品44份,阳性率为36.7%,基因型均为基因亚型AI;6份貉阳性样品,阳性率为10.0%,基因型均为集聚体D;41份家兔阳性样品,阳性率为27.7%,其中4份是集聚体B,其他是集聚体A中的基因亚型AI。结果发现在长春地区貉感染贾第虫集聚体D,长春地区的狐狸感染人兽共患型的集聚体A,家兔感染人兽共患型的集聚体A和B。研究结果为该地区十二指肠贾第虫病的防控提供了参考。     

我国部分地区羊驼十二指肠贾第虫的PCR检测和鉴定

为了解我国羊驼十二指肠贾第虫的感染情况,收集我国9个县/市的羊驼养殖基地共484份羊驼粪便样本,提取DNA后,基于核糖体小亚基(SSU rRNA)基因位点对其进行PCR扩增。结果表明:8份样本呈十二指肠贾第虫PCR检测阳性,总感染率为1.7%;9个养殖基地中,6个呈十二指肠贾第虫感染阳性。对成功测序的8条序列进行比对分析,鉴定出2种人兽共患集聚体为集聚体A (n=5)和集聚体B (n=3)。研究表明,我国部分地区羊驼十二指肠贾第虫感染率较低,但存在人兽共患集聚体。     

广东省猪十二指肠贾第虫感染现状和分子特征分析

【目的】 了解广东省不同地区猪源十二指肠贾第虫(Giardia duodenalis,简称贾第虫)的流行现状和分子特征,并评估其人兽共患风险。【方法】 从广东省10个地区采集新鲜猪粪样品,采用显微镜镜检,并应用巢式PCR对贾第虫谷氨酸脱氢酶(glutamate dehydrogenase,gdh)基因进行扩增,根据扩增结果计算不同地区和生长阶段猪贾第虫的阳性率。对所有的PCR阳性产物进行测序,将获得的贾第虫gdh基因序列进行BLAST比对,确定贾第虫的基因型;运用Mega 7.0软件的最大似然法构建进化树。【结果】 贾第虫包囊呈椭圆形,囊壁较厚,大小为(10~14)μm ×(7~10)μm,具有明显纵向轴柱,细胞核分布于轴柱两侧。521份受检样品中共检测出94份PCR阳性样品,阳性率为18.04%(94/521),其中茂名和清远的阳性率较高,分别达40.00%(10/25)和35.06%(27/77);肇庆和韶关的阳性率较低,分别为3.90%(3/77)和8.57%(3/35);佛山、江门、阳江、河源、广州和惠州的阳性率分别为11.11%(2/18)、15.31%(15/98)、11.43%(4/35)、13.33%(4/30)、9.38%(3/32)和24.47%(23/94)。不同饲养阶段的猪群的阳性率调查发现,母猪的贾第虫阳性率(24.55%)显著高于断奶仔猪(13.30%)(P<0.05),与育肥猪的贾第虫阳性率(19.23%)差异不显著(P>0.05)。基于gdh基因序列的基因分型和系统进化分析共发现5种贾第虫亚集聚体,即集聚体AⅠ和集聚体E的4种不同亚型,包括集聚体E1、E2、E10和E13,其中61.70%(58/94)测序阳性样品属于集聚体AⅠ,38.30%(36/94)属于集聚体E的不同亚型。【结论】 广东猪源贾第虫的感染较普遍,不同地区和不同生长阶段的猪感染率存在一定差异。其中,人兽共患性集聚体AⅠ为优势亚集聚体,表明广东省猪源贾第虫存在人兽跨物种传播的风险,应重视该病可能引起的公共卫生问题。     

云南省部分猪场贾第虫分子检测与分析

贾第虫是一种重要的人兽共患肠道寄生虫,可感染人和多种家畜。为获悉云南省猪场的贾第虫感染情况,采用巢式PCR,对4个猪场的129份猪粪便样品进行贾第虫TPI基因序列扩增、测序,构建系统发育树。结果显示,有2个样本为贾第虫阳性,阳性率为1.55%(2/129),均为人兽共患的集聚体B型。该结果说明:云南省猪场内存在贾第虫感染;虽然感染率不高,但存在散播风险。因此,需要加强猪场卫生防疫,做好猪粪便的无害化处理,避免因粪便污染造成疫病流行。     

宠物犬肠道寄生虫调查及其公共卫生意义分析

为了解宠物犬肠道寄生虫,尤其是人兽共患肠道寄生虫感染情况,采用甲醛-乙酸乙酯沉淀法、卢戈氏碘液染色法和饱和蔗糖溶液漂浮法对郑州市宠物犬404份粪便样品进行了调查。结果共发现10种肠道寄生虫,寄生虫总感染率为37.12%,其中球虫和贾第虫为优势虫种,感染率分别为18.32%和12.62%;7种为人兽共患虫种,贾第虫、隐孢子虫、钩虫、弓首蛔虫、狮弓蛔虫、粪类圆线虫和犬复孔绦虫感染率分别为12.62%、3.71%、3.96%、6.93%、0.20%、1.73%和0.50%;2～3种寄生虫混合感染率为9.90%。结果分析表明,寄生虫感染与样品采集地点和犬年龄统计学差异极显著(P0.01),与性别无统计学差异(P0.05)。宠物犬肠道寄生虫感染较为普遍,人兽共患寄生虫流行率较高,应加强对其监控和防治。     

广西部分地区猫隐孢子虫、十二指肠贾第虫、三毛滴虫分子流行病学调查

为了解广西部分地区猫隐孢子虫、十二指肠贾第虫和三毛滴虫的感染情况和基因型,试验采集南宁市、桂林市、柳州市、梧州市和河池市各宠物医院、流浪动物中心及送检的新鲜猫粪便样本300份,基于隐孢子虫SSU rRNA和gp60基因,十二指肠贾第虫bg、tpi和gdh基因及三毛滴虫ITS基因采用PCR方法对粪便DNA进行PCR扩增,阳性样本进行测序分析,构建遗传进化树。结果表明：共检测出22份隐孢子虫、24份十二指肠贾第虫和41份三毛滴虫阳性样本,阳性率分别为7.3%、8.0%和13.7%。幼猫三种原虫阳性率均显著高于成年猫(P<0.05),腹泻猫的阳性率显著高于未腹泻猫(P<0.05),雄性猫三毛滴虫的阳性率要显著高于雌性(P<0.05)。检测出的隐孢子虫都为猫隐孢子虫(Cryptosporidium felis,C.felis),根据gp60基因进行亚型分型,鉴定出ⅩⅨa和ⅩⅨc两种亚型。十二指肠贾第虫共鉴定出集聚体F、B和F+B三种基因型,其中集聚体F为优势基因型。说明广西部分地区猫普遍存在隐孢子虫、十二指肠贾第虫和三毛滴虫的感染,且感染的虫种和部分基因型为人兽共患型,由于宠...     

动物园动物消化道寄生虫感染情况调查

为了解动物园动物肠道寄生虫感染情况,本试验采集了来自贵阳和北京动物园33种动物,共150份粪便样品。采用饱和盐水漂浮法和离心沉淀法富集虫卵和卵囊进行显微镜检查;基于隐孢子虫、芽囊原虫、毕氏肠微孢子虫和十二指肠贾第虫的特异性基因位点对人兽共患原虫进行PCR检测和序列比对分析。结果显示,动物园动物寄生虫总感染率为64.0%。显微镜检查出的寄生虫包括毛首线虫(20.0%)、细颈线虫(2.7%)、艾美耳球虫(14.7%)和其他线虫(25.3%)。PCR检测4种肠道原虫的感染率分别为：隐孢子虫1.3%、毕氏肠微孢子虫8.7%、十二指肠贾第虫12.0%和芽囊原虫32.0%。序列比对结果显示,存在2种隐孢子虫虫种(安氏隐孢子虫和泛在隐孢子虫);7种毕氏肠微孢子虫基因型(SC02、BEB6、Type IV、PigEBITS 7、Peru8、PtEb IX和D);2种十二指肠贾第虫基因型(B和E);8种芽囊原虫基因亚型(ST1、ST2、ST3、ST5、ST8、ST10、ST13和ST14)。结果表明,贵州和北京动物园动物肠道寄生虫感染非常普遍,并且存在多种人兽共患虫种和基因型。做好动物园寄生虫病的防控不...     

牛源贾第虫的形态学观察与纯化

贾第鞭毛虫(Giardia lambliaStiles,1915,亦称G.intestinalis或G.duodenalis,简称贾第虫)是一种人兽共患的寄生原虫,寄生于哺乳动物的消化道内,引起人和多种动物以腹泻和消化不良为主要症状的贾第虫病。贾第虫在宿主小肠肠腔表面生长和无性繁殖,生活史简单,可通过其包囊传播,水是重要的传播媒介[1]。贾第虫呈全球性分布,对人的危害十分严重。在亚洲、非洲和拉丁美洲,大约有28亿人为有症状的贾第虫病病人,每年有50万新感染病例[2]。同时,贾第虫也是动物最常见的寄生虫,家畜、伴侣动物和许多野生动物已被证明是贾第虫的宿主。近年来发现这些…     

寄生性原虫影响宿主上皮细胞凋亡研究进展

凋亡是宿主与寄生虫长期进化过程中形成的调节机制之一，对寄生虫感染引起宿主先天免疫反应具有重要的调控作用。隐孢子虫、十二指肠贾第虫和芽囊原虫等寄生性原虫感染可诱导宿主胃肠道上皮细胞发生凋亡。NF-κB信号通路和非编码RNA等参与调控隐孢子虫感染诱导的宿主上皮细胞凋亡，已报道的凋亡途径包括Fas/FasL和TRAI/TRAIL途径；十二指肠贾第虫感染通过内、外两种凋亡途径调控宿主上皮细胞的凋亡，TNFR1信号通路参与细胞凋亡的调控；芽囊原虫和十二指肠贾第虫感染在诱导宿主上皮细胞凋亡水平上存在虫株间的差异。因此，探索隐孢子虫、十二指肠贾第虫和芽囊原虫诱导宿主上皮细胞凋亡机制，对研究寄生性原虫入侵机制及开发设计抗寄生性原虫药物和疫苗具有重要意义。     

Molecular characterization of Cryptosporidium and Giardia isolates from cattle from Portugal

Fecal samples from 291 calves and 176 adult cattle in Northern Portugal were screened for Cryptosporidium and Giardia using a formalin-ethyl acetate concentration method. Acid-fast staining techniques for Cryptosporidium oocyst identification and direct microscopic observation of fecal smears for Giardia cyst identification were performed so as immunofluorescence microscopy examination. Polymerase chain reaction methods were employed to determine the genotype of each isolate. Molecular characterization was performed using amplification and sequencing of the hsp70 and 18SrRNA genes of Cryptosporidium and beta-giardin gene and glutamate dehydrogenase for assemblage determination of Giardia duodenalis. Seventy-four out of 291 calves (25.4%) and 8 out of 176 adult bovines (4.5%) were positive for Cryptosporidium. Forty-one out of 291 calf samples (14.1%) and 1 out of 176 adults samples (0.57%) were positive for Giardia. From the Cryptosporidium positive samples we obtained 63 isolates from calves samples and 7 isolates from adult samples. Additionally, Giardia was isolated in 13 out of 41 positive samples from calves and it was also possible to isolate Giardia from the positive adult sample. Molecular characterization of the Cryptosporidium and Giardia isolates showed us that C. parvum and G. duodenalis assemblage E were the prevalent species. C. parvum may infect humans, representing a potential public health risk. On the other hand, the assemblages B and A2 of Giardia, previously described in humans, were here identified in cattle. Further studies will be needed for determine the importance of cattle as carrier of zoonotic assemblages of G. duodenalis.     

Prevalence of Giardia duodenalis assemblages among dairy herds in the New York City Watershed

A longitudinal herd-level study was carried out to determine the cumulative incidence of Giardia duodenalis infections in dairy cattle in the New York City Watershed. We also sought to assess the changes in infection pattern of animals diagnosed as shedding Giardia over time, determine risk factors that may be associated with G. duodenalis infections, and identify potentially zoonotic infections. A total of 2109 fecal samples were randomly collected from dairy cattle at 34 farms in the New York City Watershed on a seasonal basis. A total of 504 Giardia-positive samples were identified by zinc sulfate flotation. The overall cumulative incidence of G. duodenalis based on flotation results was 23.9% with 73.8% of all infections occurring in animals under 180 days of age (372/504). The intensity of infection ranged from 2 to 563,200 cysts/gram of feces. Cattle shedding Cryptosporidium spp. oocysts were twice as likely to shed G. duodenalis cysts in comparison to the animals that did not shed oocysts (1.81 95% CI 1.26-2.60 p=0.0012). In the multivariate analysis, only the age of the animal and the presence of dogs on the farm were significantly associated with the likelihood of shedding G. duodenalis. DNA was extracted from positive samples and analyzed by polymerase chain reaction (PCR) of the beta-giardin and triosephosphate isomerase genes of Giardia spp. 304 samples were analyzed by PCR of which 131 were sequenced. 22.1% of sequenced samples were identified as assemblage A and 77.9% were identified as assemblage E. Interestingly, 100% of specimens identified as assemblage A were from calves under 84 days of age indicating that younger cattle are important reservoirs for potentially zoonotic assemblages of G. duodenalis.     

Giardia duodenalis and Cryptosporidium spp. in a veterinary college bovine teaching herd

In a preliminary study, we commonly identified Giardia duodenalis in adult dairy cattle from a veterinary college teaching herd. Therefore, the present study was carried out in order to better understand the potential of adult cattle to act as a source for G. duodenalis infections for students and staff at the veterinary college. Fecal samples were collected bi-weekly from this herd of adult cattle (n=30) over an 8-month period to determine the prevalence of G. duodenalis and Cryptosporidium spp. within the herd. Nested PCR followed by DNA sequencing was then performed on a subset of positive samples in order to better understand the zoonotic potential of these infections. Every cow was sampled between 11 and 18 times, depending on the date the animal joined the teaching herd. In total, 507 fecal samples were collected from 30 different cows and examined for cysts and oocysts using epifluorescence microscopy. G. duodenalis prevalence during the course of the study ranged from 37% (11/30) to 64% (18/28), with a mean of 49%. Cumulative G. duodenalis prevalence was 73% (22/30). Zoonotic G. duodenalis assemblage A genotype was identified in 43% (6/14) of the G. duodenalis-positive samples on which PCR and genetic sequencing were successfully performed. G. duodenalis assemblage E was identified in 57% (8/14) of these samples. Cryptosporidium spp. oocysts were not detected in the feces of any cows during the study period. The presence of the zoonotic G. duodenalis assemblage A in 43% of the sequenced samples indicates that there is a potential risk of infection for students and staff at this research and teaching facility, although the roles of cows as sources of giardiasis in humans remain uncertain. Furthermore, due to the large amount of feces they produce, adult cattle may serve as important sources for G. duodenalis infections in young cattle, or other animals in the facility, despite relatively low numbers of cysts excreted per gram of feces. In contrast, the results of this study indicate that this herd posed a negligible risk of transmitting Cryptosporidium parvum infections to humans.     

Molecular evidence for zoonotic transmission of Giardia duodenalis among dairy farm workers in West Bengal, India

No study in the past has examined the genetic diversity and zoonotic potential of Giardia duodenalis in dairy cattle in India. To assess the importance of these animals as a source of human G. duodenalis infections and determine the epidemiology of bovine giardiasis in India, fecal samples from 180 calves, heifers and adults and 51 dairy farm workers on two dairy farms in West Bengal, India were genotyped by PCR-RFLP analysis of the β-giardin gene of G. duodenalis followed by DNA sequencing of the nested PCR products. The overall prevalence of G. duodenalis in cattle was 12.2% (22/180), the infection being more prevalent in younger calves than in adult cattle. Zoonotic G. duodenalis Assemblage A1 was identified in both calves and workers although the most prevalent genotype detected in cattle was a novel Assemblage E subgenotype. These findings clearly suggest that there is a potential risk of zoonotic transmission of G. duodenalis infections between cattle and humans on dairy farms in India.     

Cryptosporidium and Giardia as foodborne zoonoses

Cryptosporidium and Giardia are major causes of diarrhoeal disease in humans, worldwide and are major causes of protozoan waterborne diseases. Both Cryptosporidium and Giardia have life cycles which are suited to waterborne and foodborne transmission. There are 16 'valid'Cryptosporidium species and a further 33+ genotypes described. Parasites which infect humans belong to the Giardia duodenalis "type", and at least seven G. duodenalis assemblages are recognised. Cryptosporidium parvum is the major zoonotic Cryptosporidium species, while G. duodenalis assemblages A and B have been found in humans and most mammalian orders. In depth studies to determine the role of non-human hosts in the transmission of Cryptosporidium and Giardia to humans are required. The use of harmonised methodology and standardised and validated molecular markers, together with sampling strategies that provide sufficient information about all contributors to the environmental (oo)cyst pool that cause contamination of food and water, are recommended. Standardised methods for detecting (oo)cysts in water are available, as are optimised, validated methods for detecting Cryptosporidium in soft fruit and salad vegetables. These provide valuable data on (oo)cyst occurrence, and can be used for species and subspecies typing using appropriate molecular tools. Given the zoonotic potential of these organisms, epidemiological, source and disease tracking investigations involve multidisciplinary teams. Here, the role of the veterinarian is paramount, particularly in understanding the requirement for adopting comprehensive sampling strategies for analysing both sporadic and outbreak samples from all potential non-human contributors. Comprehensive sampling strategies increase our understanding of parasite population biology and structure and this knowledge can be used to determine what level of discrimination is required between isolates. Genetic exchange is frequent in C. parvum populations, leading to recombination between alleles at different loci, the generation of a very large number of different genotypes and a high level of resolution between isolates. In contrast, genetic exchange appears rare in Cryptosporidium hominis and populations are essentially clonal with far fewer combinations of alleles at different loci, resulting in a much lower resolution between isolates with many being of the same genotype. Clearly, more markers provide more resolution and high throughput sequencing of a variety of genes, as in multilocus sequence typing, is a way forward. Sub-genotyping tools offer increased discrimination, specificity and sensitivity, which can be exploited for investigating the epidemiology of disease, the role of asymptomatic carriers and contaminated fomites and for source and disease tracking for food and water contaminated with small numbers of (oo)cysts.     

Evaluation of the zoonotic potential of Giardia duodenalis in fecal samples from dogs and cats in Ontario

This study determined the distribution and zoonotic potential of Giardia duodenalis assemblage types among canine and feline fecal samples from Ontario. The effectiveness of Giardia assemblage typing methods by sequencing the genes of small subunit ribosomal RNA (ssu-rRNA), β-giardin (bg), glutamate dehydrogenase (gdh), and triose phosphate isomerase (tpi) was evaluated simultaneously. From 2008 to 2010, 118 canine and 15 feline Giardia positive fecal samples were tested. The ssu-rRNA sequencing method typed 64% (75/118) and 87% (13/15) of the Giardia-positive canine and feline samples, respectively. Among the typeable samples, 68% (51/75) of canine samples contained G. duodenalis assemblage D and 31% (23/75) contained G. duodenalis assemblage C (both non-zoonotic assemblage types). Only 1% (1/75) of the typeable canine samples contained a potentially zoonotic assemblage B. In contrast, 100% (13/13) of the typeable feline samples contained potentially zoonotic assemblages A (n = 12) or B (n = 1).     

Molecular epidemiology of cryptosporidium and giardia in humans on prince edward island, Canada: evidence of zoonotic transmission from cattle

To determine the zoonotic potential of Cryptosporidium and Giardia in Prince Edward Island (PEI), Canada, 658 human faecal specimens were screened that were submitted to the Queen Elizabeth Hospital diagnostic laboratory. Overall, 143 (22%) samples were Cryptosporidium positive, while three (0.5%) were positive for Giardia. Successful genotyping of 25 Cryptosporidium isolates by sequence analysis of the HSP70 gene revealed that 28 and 72% were C. hominis and C. parvum, respectively. Cryptosporidium isolates from humans and previously genotyped C. parvum from beef cattle were subtyped by sequence analysis of the GP60 gene. Subtyping identified three subtypes belonging to the family IIa. All three subtypes IIaA16G2RI (55%), IIaA16G3RI (22%) and IIaA15G2RI (22%) were found in the animal isolates, while two of the subtypes found in the animals, IIaA16G2RI (80%) and IIaA15G2RI (20%), were also identified in the human isolates. Cryptosporidium infection in humans peaked in April-June. Molecular epidemiological analysis of the human data showed a C. parvum peak in the spring and a relatively smaller peak for C. hominis in July-September. The majority (57%) of human Cryptosporidium isolates were found in children between 5 and 10 years of age. All three Giardia isolates were identified as G. duodenalis assemblage A. The overall Cryptosporidium prevalence in our human samples was high relative to other studies, but because the samples were submitted to a hospital diagnostic laboratory, the results may not be representative of the general population. Further, the presence of the same zoonotic C. parvum subtypes in cattle and human isolates implies that transmission is largely zoonotic and cattle may be a source of sporadic human infections on PEI. The presence of Giardia in people on PEI is rare, and the assemblage A found in humans might originate from humans, livestock or other domestic or wild animals.     

Molecular identification of Cryptosporidium parvum and Giardia duodenalis in the Italian water buffalo (Bubalus bubalis)

Livestock are commonly infected with protozoan parasites of the genera Cryptosporidium and Giardia, and some of the species and genotypes found in these animals have zoonotic significance. We characterized isolates of both parasites recovered from the Italian water buffalo (Bubalus bubalis), an economically important species whose milk is used for the production of "buffalo mozzarella" fresh cheese. Molecular analysis of the Cryptosporidium small subunit ribosomal DNA gene and of the Giardia beta-giardin gene shows the presence of both zoonotic parasites (Cryptosporidium parvum and Giardia duodenalis assemblage A) and host-specific parasites (G. duodenalis assemblage E), suggesting that water buffaloes can contribute to environmental contamination with oocysts and cysts potentially infectious to humans if their faeces are improperly disposed of. On the other hand, mozzarella cheese is probably a safe product, given that its production involves the treatment of cheese curd at 85-95 degrees C, which is likely to kill or inactivate the parasites.     

Genotyping of Giardia duodenalis from Southern Brown Howler Monkeys (Alouatta clamitans) from Brazil

Giardia duodenalis is a widespread intestinal protozoan that can infect humans and animals, both domestic and wild. Independent of host, infections present with the same symptoms. However, based on host specificity, Giardia isolates have been grouped into genotypes A to G. Parasites of assemblage A and B are known to infect humans, in addition to primates and a wide variety of mammals. In Brazil, hitherto Giardia genotypes were defined only for humans and domestic animals. To evaluate the genotypes of different Giardia present among other animals, fecal samples from 28 Southern Brown Howler Monkeys (Alouatta clamitans) kept in captivity from South Brazil were screened for G. duodenalis using parasitological methods. All of them were asymptomatic, but positive for Giardia. The genotype of the G. duodenalis circulating among these animals was ascertained by molecular typing, performed using amplification and sequencing of the beta-giardin gene. Sixteen of 28 samples were successfully amplified by PCR and sequencing of this gene s revealed that all of them were of the genotype A1. These findings suggest that A. clamitans represent a potential risk of environmental contamination of a G. duodenalis genotype that also infect humans, and therefore can be considered a potential reservoir for G. duodenalis of a genotype that can also infects humans. Therefore, these results highlight a potential public health problem due to the epidemiological and molecular evidence for anthropozoonotic transmission.     

The potential for zoonotic transmission of Giardia duodenalis and Cryptosporidium spp. from beef and dairy cattle in Ontario, Canada

The objective of this study was to compare the occurrence and the genotypes and species of Giardia duodenalis and Cryptosporidium spp. in beef and dairy cattle from farms in the Regional Municipality of Waterloo, Ontario, in an effort to determine the potential for zoonotic transmission from these animals. Pooled manure samples were collected from 45 dairy cattle farms and 30 beef cattle farms. The presence of Giardia cysts and Cryptosporidium oocysts was determined by immunofluorescence microscopy, while nested-PCR and DNA sequencing were used to determine genotypes and species. The overall farm prevalence was very high for both Giardia and Cryptosporidium, and was similar for dairy cattle farms (96 and 64%, respectively) and beef cattle farms (97 and 63%, respectively). However, on dairy cattle farms, G. duodenalis and Cryptosporidium spp. were detected in 44% and 6% of total pooled pen manure samples, respectively, with the occurrence of both parasites being generally higher in calves than in older animals. Most Giardia isolates were identified as either the host-adapted genotype G. duodenalis Assemblage E or the zoonotic Assemblage B. Cryptosporidium parvum and Cryptosporidium andersoni were the most frequently identified species in dairy cattle, while the non-zoonotic species Cryptosporidium ryanae and Cryptosporidium bovis were also found. On beef cattle farms, 72% and 27% of the total pooled pen manure samples were positive for Giardia and Cryptosporidium, respectively, with no obvious correlation with age. All Giardia isolates in beef cattle were identified as G. duodenalis Assemblage E, while all Cryptosporidium isolates were identified by sequence analysis as C. andersoni, although microscopic analyses, and subsequent restriction fragment length polymorphism analyses, indicated that other Cryptosporidium species were also present. The results of this study indicate that although Giardia and Cryptosporidium were identified in a higher overall percentage of the pooled beef cattle manure samples than in dairy cattle, firmly established zoonotic genotypes and species were much more common in dairy cattle than in beef cattle in this region. Dairy cattle, and especially dairy calves, may, therefore, pose a greater risk of infection to humans than beef cattle. However, these results may also provide evidence of potential zooanthroponotic transmission (human to animal).