Brar A P S, Sood N K, Kaur P, Singla L D, Sandhu B S, Gupta K, Narang D, Singh C K, Chandra M
Department of Veterinary Pathology,College of Veterinary Science,GADVASU, Ludhiana-141004,India.
Department of Veterinary Parasitology,College of Veterinary Science,GADVASU, Ludhiana-141004,India.
Epidemiol Infect. 2017 Oct;145(13):2717-2726. doi: 10.1017/S0950268817001224. Epub 2017 Aug 8.
Bovine calf scours reported to be caused by multiple aetiologies resulting in heavy mortality in unweaned calves and huge economic loss to the dairy farmers. Among these, cryptosporidiosis is an emerging waterborne zoonoses and one of the important causes of neonatal calf diarrhoea. Poor immune response coupled with primary cryptosporidial infections predispose neonatal calves to multiple secondary infections resulting in their deaths. In the present study, faecal samples from 100 diarrhoeic calves randomly picked up out of 17 outbreaks of bovine calf diarrhoea in periurban Ludhiana, Punjab in Northern India were subjected to conventional (microscopy, modified Zeihl-Neelsen (mZN) staining) and immunological and molecular techniques (faecal antigen capture ELISA and PCR) for detection of primary Cryptosporidium parvum infection as well as other frequently reported concurrent pathogens, viz. rotavirus and coronavirus, Salmonella spp., Escherichia coli, Clostridium perfringens and Eimeria spp. The faecal antigen capture ELISA and PCR revealed 35% prevalence of C. parvum in contrast to 25% by mZN staining with a relatively higher prevalence (66·7%) in younger (8-14-day-old) calves. The detection rate of the other enteropathogens associated with C. parvum was 45·71% for C. perfringens followed by Salmonella spp (40·0%), rotavirus (36·0%), coronavirus (16·0%), E. coli (12·0%) and Eimeria spp (4·0%) The sensitivity for detection of C. parvum by ELISA and mZN staining in comparison to PCR was 97·14% and 72·72%, respectively. An important finding of the study was that C. parvum alone was found in only 10% of the diarrhoeic faecal samples, whereas, majority of the samples (90%) showed mixed infections ranging from a combination of two to five agents. This is the first documentary proof of C. parvum and associated pathogens responsible for severe periurban outbreaks of bovine calf diarrhoea culminating in heavy mortality from Northern India.
据报道，犊牛腹泻由多种病因引起，导致未断奶犊牛死亡率很高，给奶农造成巨大经济损失。其中，隐孢子虫病是一种新出现的水源性人畜共患病，也是新生犊牛腹泻的重要病因之一。免疫反应低下加上原发性隐孢子虫感染，使新生犊牛易发生多种继发性感染，导致死亡。在本研究中，从印度北部旁遮普邦卢迪亚纳市城郊17起犊牛腹泻疫情中随机选取100头腹泻犊牛的粪便样本，采用传统方法（显微镜检查及改良齐-尼（mZN）染色）以及免疫和分子技术（粪便抗原捕获ELISA和PCR），检测原发性微小隐孢子虫感染以及其他常见的并发病原体，即轮状病毒、冠状病毒、沙门氏菌属、大肠杆菌、产气荚膜梭菌和艾美耳球虫属。粪便抗原捕获ELISA和PCR显示微小隐孢子虫的感染率为35%，而mZN染色的感染率为25%，在较年幼（8 - 14日龄）犊牛中的感染率相对较高（66.7%）。与微小隐孢子虫相关的其他肠道病原体的检出率依次为：产气荚膜梭菌45.71%，沙门氏菌属（40.0%），轮状病毒（36.0%），冠状病毒（16.0%），大肠杆菌（12.0%）和艾美耳球虫属（4.0%）。与PCR相比，ELISA和mZN染色检测微小隐孢子虫的灵敏度分别为97.14%和72.72%。该研究的一个重要发现是，仅在10%的腹泻粪便样本中发现了微小隐孢子虫，而大多数样本（90%）显示为两种至五种病原体的混合感染。这是印度北部城郊严重犊牛腹泻疫情导致高死亡率的微小隐孢子虫及相关病原体的首个文献证据。
