Cryptosporidium and Giardia infections can negatively impact livestock health and reduce productivity, and some species and genotypes infecting livestock have zoonotic potential. Infection occurs via the faecal-oral route. Waterborne infections are a recognised source of infection for humans, but the role of livestock drinking water as a source of infection in livestock has not been described. This study aimed to determine whether contaminated drinking water supplies, such as farm dams, are a likely transmission source for Cryptosporidium and Giardia infections for extensively managed sheep. Dam water samples (n = 47) were collected during autumn, winter and spring from 12 farm dams located on six different farms in south west Western Australia, and faecal samples (n = 349) were collected from sheep with access to these dams. All samples were initially screened for Cryptosporidium spp. at the 18S locus and Giardia spp. at the gdh gene using qPCR, and oocyst numbers were determined directly from the qPCR data using DNA standards calibrated by droplet digital PCR. Cryptosporidium-positive sheep faecal samples were typed and subtyped by sequence analysis of 18S and gp60 loci, respectively. Giardia-specific PCR and Sanger sequencing targeting tpi and gdh loci were performed on Giardia- positive sheep faecal samples to characterise Giardia duodenalis assemblages. To identify Cryptosporidium and Giardia spp. in dam water samples, next-generation sequencing analysis of 18S and gdh amplicons were performed, respectively. Two species of Cryptosporidium (Cryptosporidium xiaoi and Cryptospordium ubiquitum (subtype family XIIa)) were detected in 38/345 sheep faecal samples, and in water from 9/12 farm dams during the study period, with C. xiaoi the species most frequently detected in both faeces and dam water overall. Giardia duodenalis assemblages AI, AII and E were detected in 36/348 faecal samples and water from 10/12 farm dams. For dam water samples where oo/cysts were detected by qPCR, Cryptosporidium oocyst concentration ranged from 518–2429 oocysts/L (n = 14), and Giardia cyst concentration ranged from 102 to 1077 cysts/L (n = 17). Cryptosporidium and Giardia with zoonotic potential were detected in farm dam water, including C. ubiquitum, C. hominis, C. parvum, C. cuniculus, C. xiaoi, and G. duodenalis assemblages A, B and E. The findings suggest that dam water can be contaminated with Cryptosporidium species and G. duodenalis assemblages that may infect sheep and with zoonotic potential, and farm dam water may represent one source of transmission for infections.

隐孢子虫和贾第鞭毛虫感染可能会对牲畜健康产生负面影响，并降低生产力，而且某些感染牲畜的物种和基因型具有人畜共患病的潜力。感染通过粪便-口腔途径发生。水传播的感染是人类公认的感染源，但尚未描述牲畜饮用水作为牲畜感染源的作用。这项研究旨在确定受污染的饮用水供应源（例如农场水坝）是否可能是广泛管理的绵羊的隐孢子虫和贾第鞭毛虫感染的传播源。大坝水样（n在秋天，冬季和春季，从位于澳大利亚西部西南6个不同农场的12个农场水坝中收集了47个粪便，并从绵羊中采集了粪便样本（n = 349）。最初筛选所有样品的隐孢子虫属。在18S所在地和贾第虫属。使用qPCR在gdh基因上鉴定卵囊数目，并使用通过液滴数字PCR校准的DNA标准直接从qPCR数据确定卵囊数。通过18S和gp60基因座的序列分析分别对隐孢子虫阳性绵羊粪便样品进行分型和亚型化。贾第鞭毛虫特异性PCR和Sanger测序靶向tpi对贾第鞭毛虫（Giardia-阳性绵羊粪便样本）进行了gdh和gdh基因座鉴定十二指肠贾第鞭毛虫组合。鉴定隐孢子虫和贾第虫属。在大坝水样中，分别进行了18S和gdh扩增子的下一代测序分析。在研究期间，在38/345只绵羊粪便样本和9/12农场大坝的水中检出了两种隐孢子虫（Cryptosporidium xiaoi和Cryptospordium ubiquitum（亚型XIIa家族）），其中C. xiaoi最为常见。粪便和大坝水总体而言。在36/348粪便样本和10/12农场水坝的水中检测到十二指肠Giardia duodenalis组合AI，AII和E。对于通过qPCR检测到oo /囊肿的大坝水样，隐孢子虫卵囊的浓度范围为518–2429卵囊/ L（n = 14），贾第鞭毛虫的囊肿浓度范围为102至1077囊肿/ L（n = 17）。隐孢子虫和贾第鞭毛虫人畜共患潜力在农场坝水进行检测，包括C. ubiquitum，C.人型支原体，微小隐孢子虫，C. cuniculus，C.小i，和G. duodenalis组合A，B和E的结果表明，坝水可能被隐孢子虫污染可能感染绵羊并具有人畜共患病潜力的物种和十二指肠组合物，而农场的大坝水可能是感染的一种传播来源。