Table_1_Dairy Calves in Uruguay Are Reservoirs of Zoonotic Subtypes of Cryptosporidium parvum and Pose a Potential Risk of Surface Water Contamination.DOCX

Cryptosporidium parvum, a major cause of diarrhea in calves, is of concern given its zoonotic potential. Numerous outbreaks of human cryptosporidiosis caused by C. parvum genetic subtypes are reported yearly worldwide, with livestock or water being frequently identified sources of infection. Although cryptosporidiosis has been reported from human patients in Uruguay, particularly children, epidemiologic information is scant and the role of cattle as reservoirs of zoonotic subtypes of C. parvum has not been explored. In this study, we aimed to (a)-identify C. parvum subtypes infecting dairy calves in Uruguay (including potentially zoonotic subtypes), (b)-assess their association with calf diarrhea, (c)-evaluate their spatial clustering, and (d)-assess the distance of infected calves to surface watercourses draining the farmlands and determine whether these watercourses flow into public water treatment plants. Feces of 255 calves that had tested positive for Cryptosporidium spp. by antigen ELISA were selected. Samples had been collected from 29 dairy farms in seven Uruguayan departments where dairy farming is concentrated and represented 170 diarrheic and 85 non-diarrheic calves. Selected samples were processed by nested PCRs targeting the 18S rRNA and gp60 genes followed by sequencing to identify C. parvum subtypes. Of seven C. parvum subtypes detected in 166 calves, five (identified in 143 calves on 28/29 farms) had been identified in humans elsewhere and have zoonotic potential. Subtype IIaA15G2R1 was the most frequent (53.6%; 89/166), followed by IIaA20G1R1 (24.1%; 40/166), IIaA22G1R1 (11.4%; 19/166), IIaA23G1R1 (3.6%; 6/166), IIaA17G2R1 (3%; 5/166), IIaA21G1R1 (2.4%; 4/166), and IIaA16G1R1 (1.8%; 3/166). There were no significant differences in the proportions of diarrheic and non-diarrheic calves infected with any of the C. parvum subtypes. Two spatial clusters were detected, one of which overlapped with Uruguay's capital city and its main water treatment plant (Aguas Corrientes), harvesting surface water to supply ~1,700,000 people. Infected calves on all farms were within 20–900 m of a natural surface watercourse draining the farmland, 10 of which flowed into six water treatment plants located 9–108 km downstream. Four watercourses flowed downstream into Aguas Corrientes. Calves are reservoirs of zoonotic C. parvum subtypes in Uruguay and pose a public health risk.

微小隐孢子虫（Cryptosporidium parvum），作为犊牛腹泻的主要原因，其潜在的动物源性传播能力引起了广泛关注。全球范围内，每年均有由C. parvum遗传亚型引起的人类隐孢子虫病爆发病例报告，其中牲畜或水源常常被确认为感染源。尽管在乌拉圭已有人类患者报告患有隐孢子虫病，尤其是儿童，但流行病学信息匮乏，且尚未探讨牛作为C. parvum动物源性亚型储存宿主的作用。在本研究中，我们旨在（a）识别乌拉圭奶牛犊感染微小隐孢子虫的亚型（包括潜在的动物源性亚型），（b）评估其与犊牛腹泻的关联，（c）评估其空间聚集性，（d）评估感染犊牛与农田排水表面水系的距离，并确定这些水系是否流入公共水处理厂。选取了255头通过抗原ELISA检测呈阳性（Cryptosporidium spp.）的犊牛粪便样本。样本采集自七个乌拉圭部门中的29个奶牛场，这些奶牛场集中了奶牛养殖业，并代表了170头腹泻犊牛和85头非腹泻犊牛。所选样本通过针对18S rRNA和gp60基因的巢式PCR进行加工，随后进行测序以识别微小隐孢子虫亚型。在166头犊牛中检测到七种微小隐孢子虫亚型，其中五种（在28/29个农场143头犊牛中鉴定）在其他地区的人类中已有发现，并具有动物源性传播潜力。亚型IIaA15G2R1最为常见（53.6%；89/166），其次是IIaA20G1R1（24.1%；40/166）、IIaA22G1R1（11.4%；19/166）、IIaA23G1R1（3.6%；6/166）、IIaA17G2R1（3%；5/166）、IIaA21G1R1（2.4%；4/166）和IIaA16G1R1（1.8%；3/166）。感染任何一种微小隐孢子虫亚型的腹泻和非腹泻犊牛的比例之间没有显著差异。检测到两个空间聚集区，其中一个与乌拉圭首都及其主要水处理厂（Aguas Corrientes）重叠，该厂从地表水中采集水源，为约170万人供水。所有农场的感染犊牛均位于距离农田自然地表水系20–900米范围内，其中10个水系流向下游6个水处理厂，距离为9–108公里。四个水系流向下游进入Aguas Corrientes。在乌拉圭，犊牛是动物源性微小隐孢子虫亚型的储存宿主，构成了公共卫生风险。