腹泻犊牛感染的隐孢子虫种类鉴定及基因分型

为了鉴定陕西省某牛场有腹泻症状犊牛感染的隐孢子虫(Cryptosporidium)种类及其分子生物学特征,基于隐孢子虫18SrRNA和GP60基因位点,对从该场采集到的3例腹泻犊牛新鲜粪便样品进行PCR扩增和序列分析。结果表明,3份样品全部为Ⅱd型微小隐孢子虫(C. parvum),其中2份为ⅡdA30G4,1份为Ⅱd A34G4。说明在该牛场中的腹泻犊牛存在微小隐孢子虫感染,需引起养殖者的重视。     

一例冠状病毒、轮状病毒混合感染引起犊牛腹泻的诊治

2022年3月,河南省某规模化奶牛养殖场发生一起新生犊牛腹泻病例,在流行病学调查、临床症状观察、病理剖检的基础上,采集6头腹泻犊牛的新鲜粪便进行了寄生虫卵检查、小球隐孢子虫、牛轮状病毒、冠状病毒、大肠杆菌K99抗体检测,血液样品进行了牛病毒性腹泻病毒抗原检测,组织样品进行了细菌分离。结果表明牛轮状病毒抗原6头阳性,阳性率100%;冠状病毒抗原4头阳性、2头阴性,阳性率66.7%;其他病原均为阴性。根据临床症状、病理变化和实验室检测结果,确诊该病例为牛冠状病毒和轮状病毒混合感染引起的犊牛腹泻。根据诊断结果,采取了改善饲养管理、补液、收敛、止泻等综合性防治措施,疫情得到了有效的控制,为临床防治犊牛腹泻提供了参考。     

宁夏地区犊牛腹泻的病原调查

为了解宁夏地区奶牛犊牛腹泻的病原微生物种类及流行病学情况,2017年6月至12月对宁夏地区20个牧场有临床腹泻症状的犊牛,随机采集127份腹泻粪便样品,采用快速检测试剂盒对轮状病毒、隐孢子虫、大肠杆菌和贾第鞭毛虫4种病原微生物进行了抗原检测。结果显示:在127份腹泻粪样中,轮状病毒的阳性检出率为32. 28%(41/127),隐孢子虫的阳性检出率为25. 20%(32/127),大肠杆菌阳性检出率为11. 02%(14/127),贾第鞭毛虫阳性检出率为4. 72%(6/127)。结果表明:宁夏部分奶牛养殖区犊牛已经存在着较为严重的轮状病毒和隐孢子虫病感染,此调查为宁夏制定科学有效的综合防控措施提供了有效依据,对促进宁夏地区奶产业健康持续发展具有重要意义。     

致犊牛腹泻肠道原虫的分子生物学鉴定

为确定导致犊牛腹泻的寄生原虫种类及分子学特性,利用基于隐孢子虫核糖体小亚基RNA、蓝氏贾第虫β-贾第素和毕氏肠微孢子虫内转录间隔区的分子生物学技术对腹泻犊牛的粪便样品进行鉴定。结果表明,引起犊牛腹泻的寄生原虫包括微小隐孢子虫、安氏隐孢子虫、瑞氏隐孢子虫、E型蓝氏贾第虫和多种基因型的毕氏肠微孢子虫,并且存在多种原虫混合感染。说明原虫是引起犊牛腹泻的重要病原,畜牧业临床中应加强原虫病的防控。     

河南省部分地区乳牛隐孢子虫病的流行病学调查

为进一步掌握乳牛隐孢子虫病在河南省的流行动态,从河南省郑州、开封、济源和鹤壁4个地区9个奶牛场采集12月龄以内的乳牛粪便样品582份,用饱和蔗糖溶液漂浮法和改良抗酸染色法进行检测。结果显示,隐孢子虫总感染率为26．12％（152／582）。其中,断乳前犊牛（5日龄至2月龄）隐孢子虫感染率为30．91％（51／165）,断乳后犊牛（3～12月龄）感染率为24．22％（101／417）。依据形态数值初步鉴定为2种隐孢子虫,即微小隐孢子虫和安氏隐孢子虫。微小隐孢子虫在断乳前犊牛阳性样品中的比率为50．98％（26／51）,在断乳后乳牛阳性样品中的比率为9．90％（10／101）。另外,饲养方式（断乳前犊牛单独隔离饲养和未隔离饲养）对断乳前犊牛2种隐孢子虫的感染率有显著影响。     

黑龙江某规模化牛场犊牛腹泻病原检测及防控建议

2020年5-6月份,黑龙江省某奶牛场的新生犊牛出现精神沉郁、消瘦、水样腹泻等临床症状。为确诊发病原因,采集腹泻犊牛肛拭子、粪便等样品20份,采用PCR技术检测牛轮状病毒、牛冠状病毒、牛病毒性腹泻黏膜病病毒及隐孢子虫,细菌分离培养和致病性试验鉴定可能的致病细菌。结果表明,在20份腹泻粪样中,未检出牛轮状病毒、牛冠状病毒及牛病毒性腹泻黏膜病毒,隐孢子虫的阳性率为25%(5/20),致病性大肠杆菌检出率为75%(15/20)。说明该奶牛场犊牛养殖区存在较为严重的大肠杆菌及隐孢子虫感染。     

犊牛腹泻病原调查及与临床症状相关性分析

为了解我国主要奶业产区导致犊牛腹泻的主要病原,于2015年6月至2016年1月,采集华北、西北、东北主要奶业产区内的176份犊牛腹泻粪样,并对样品中的牛冠状病毒(BCOV)、牛轮状病毒(BRV)、牛病毒性腹泻病毒(BVDV)、大肠杆菌K99、隐孢子球虫、肠兰伯氏鞭毛虫和其他致病菌进行检测,同时结合临床收集的资料,分析病原与临床症状的相关性。结果表明,不同奶业产区内导致犊牛腹泻的病原存在一定差异,西北地区导致犊牛腹泻的病原主要是痢疾杆菌,而华北地区则是隐孢子球虫和肠兰伯氏鞭毛虫,东北地区主要是牛轮状病毒和肠兰伯氏鞭毛虫,且病原感染与犊牛腹泻的临床症状存在明显相关性。     

犊牛腹泻血液生化指标与主成分分析研究

为考察由不同病原引起的腹泻对犊牛血液生化指标的影响,采集39例犊牛的粪便和血清,利用细菌鉴别培养、RT-PCR病毒检测试剂盒、胶体金多重病原检测试剂盒等对病原进行检测,采集的血清用全自动血液生化分析仪进行测定。检测结果表明,选择的39例12-14日龄的腹泻犊牛粪便中检测到单纯由细菌、或病毒、或寄生虫感染分别为17份、10份、7份,另外3份为混合感染,还有2份样品中未检测到病原;采用主成分分析法将12项血清生化指标转化为综合性更强的4种主成分,结果显示4种主成分的聚类结果与病原检测结果一致;对不同病原所致腹泻犊牛各项血清生化指标进行方差分析,发现病毒性腹泻的总胆红素CT-BIL、总胆固醇(CT)水平与其他病原所致的腹泻有显著性差异(P0.01)。     

奶牛场55例犊牛腹泻主要病原调查

为了解杨凌周边部分奶牛场犊牛腹泻的病原种类及感染情况,通过对杨凌2个奶牛场的55例腹泻犊牛取样检测,采用快检试剂盒对牛病毒性腹泻病毒、轮状病毒、大肠埃希菌K99、贾第虫以及隐孢子虫进行检测。结果发现不同病原的总体感染率分别为隐孢子虫35.7%,轮状病毒21.4%,大肠埃希菌K9921.4%,贾第虫7.1%,牛病毒性腹泻病毒未检出。结果表明,调查的2个奶牛场犊牛腹泻病原主要为隐孢子虫、轮状病毒、大肠埃希菌K99、贾第虫,其中隐孢子虫总体感染情况最为严重,未检出牛病毒性腹泻病毒。     

河南省绵羊隐孢子虫病的流行病学调查

为获得河南省绵羊隐孢子虫的流行病学资料,应用饱和蔗糖溶液漂浮法和改良抗酸染色法对河南省4个地区的5个羊场共1701份绵羊粪样进行了检测,并对绵羊隐孢子虫感染的风险因素进行了评估。结果表明,查出隐孢子虫阳性样品80份,总阳性率为4．70％,3周龄羔羊和产后3周母羊的感染率最高,分别为41.18%和6．29％。根据隐孢子虫卵囊的形态学数值分析结果,将发现于绵羊的隐孢子虫卵囊初步鉴定为微小隐孢子虫和安氏隐孢子虫。同时发现绵羊隐孢子虫感染存在年龄差异,但未见明显的季节性变化。     

A case-control study of selected pathogens including verocytotoxigenic Escherichia coli in calf diarrhea on an Ontario veal farm.

A case-control study of diarrheal disease in veal calves was conducted over a three month period on a single large veal farm in southern Ontario. One hundred diarrheic calves (cases) were identified by visual examination of their feces. Each case was matched to two nondiarrhetic controls from the same room on the same day, and a fecal sample was obtained from each animal. Fecal consistency of cases and controls was observed daily for one week following sample collection. Control calves which developed diarrhea during that period were excluded from the study. Breed, sex and the date and nature of antimicrobial drugs administered to each calf were recorded. Moisture content of fecal samples was measured by weighing samples before and after oven drying. Samples were screened for verocytotoxigenic Escherichia coli (VTEC) using a Vero cell assay, for enterotoxigenic E. coli (ETEC) using an immunoblot procedure with anti-K99 monoclonal antibodies, and for Salmonella species using modified semi-solid Rappaport-Vassiliadis medium. A latex agglutination test was used to detect rotaviruses, and samples were examined for cryptosporidia using sucrose wet mounts. No VTEC were identified in cases or controls. One calf was positive for Salmonella and three were positive for ETEC. Rotaviruses were detected in four cases and four controls. A significant positive association was found between diarrhea and infection with Cryptosporidium. This study thus provided no evidence of an association between diarrhea and infection with either VTEC, ETEC, Salmonella spp. or rotaviruses in the population examined. On the other hand our results do suggest that Cryptosporidium infection may promote transient diarrheal disease in veal calves in Ontario.     

Prevalence of Cryptosporidium parvum infection in Punjab (India) and its association with diarrhea in neonatal dairy calves

A prevalence study was contemplated to determine the prevalence of Cryptosporidium spp. in dairy farms in Punjab, India. The cryptosporidium oocysts were detected from 50 and 25.68% from 80 diarrheic and 74 non-diarrheic animals, respectively. Both shedding and intensity of shedding were significant in calves with diarrhea. The Cryptosporidium spp. appears to be common in dairy calves and an important contributor of calf diarrhea in the Punjab province. The prevalence of the infection peaked in young calves between 0 and 30 days in both the diarrheic and non-diarrheic groups (86.4 and 66.6%, respectively). The percentage distribution of positive samples, with reference to age groups of diarrheic and non-diarrheic animals was negatively correlated with increase in age. High mortality rate and case fatality rate of 35.2 and 44.4% were observed in young calves between 0 and 30 days of age.     

2株致犊牛腹泻大肠杆菌的分离鉴定和药敏试验

赣西某肉牛养殖场有犊牛出现消瘦、食欲下降和排腥臭稀便等症状,为确定病原采集了腹泻犊牛的新鲜粪便,采用Bio-X犊牛消化道五联原位快速诊断试剂盒进行快速诊断,同时进行病原菌的分离与鉴定;为了确定病原菌对抗菌药的敏感性,选取了磺胺嘧啶钠、青霉素、链霉素、土霉素和氧氟沙星等多种抗菌药对病原菌进行体外抑菌试验。通过临床快速诊断与实验室诊断确定该病是由大肠杆菌引起的,体外抑菌试验结果显示2株分离菌对环丙沙星高度敏感,对青霉素和头孢拉定等抗菌药表现完全耐药。该养殖场依据药敏试验结果合理用药并采取多种防治措施,数日后无新发病例并且发病牛的病情得到较好控制。     

Enteric infections in veal calves: a longitudinal study on four veal calf units

Forty-five calves on four veal calf units were monitored during the first four weeks after their arrival. Faecal samples were collected on alternate days and screened for the presence of rotaviruses, bovine coronavirus, Cryptosporidium oocysts, K99 positive strains of E. coli and Salmonella spp. Rotaviruses and Cryptosporidium were the most commonly detected agents (78% and 60% respectively of the calves). Bovine coronavirus was detected in the faeces of 18% of the calves, whilst K99 positive E. coli was only found in 2 samples from one calf. Salmonella spp. were not isolated from any of the 646 faecal samples examined. Shedding of rotaviruses occurred in a bimodal pattern beginning in the first week of the survey. Cryptosporidium oocysts were detected most frequently in the interval between the two peaks of rotavirus shedding. The presence of rotaviruses or Cryptosporidium oocysts in faeces was not strongly associated with scour, nor were combined infections with these agents or the cases of bovine coronavirus infection. The condition of the calves throughout the survey was generally satisfactory.     

Cryptosporidium infection in calves from a rural area of Buenos Aires, Argentina

Dairy calves less than 1 month of age are commonly infected with Cryptosporidium spp. The objective of the present study was to evaluate the prevalence of Cryptosporidium spp. among dairy calves or=810 oocysts/field. This study shows that Cryptosporidium spp. is one of the causes of calf neonatal diarrhoea in a rural area of Buenos Aires, Argentina. The highest intensity of infection reported for the 相似文献   

Prevalence of Cryptosporidium parvum infection in southwestern Ontario and its association with diarrhea in neonatal dairy calves

Cryptosporidium parvum infection was detected in 203 (40.6%) of 500 Ontario dairy calves aged 7 to 21 d, on a convenience sample of 51 farms with a history of calf diarrhea. Within-farm prevalence ranged from 0% to 70%, and both shedding and intensity of shedding were significantly associated with diarrhea. This parasite appears to be common in Ontario dairy calves and important as a cause of dairy calf scours in the province.     

Sporadic cryptosporidiosis in a rural population is asymptomatic and associated with contact to cattle

Fecal samples each followed by a completed questionnaire were obtained from 233 persons representing 80 households. Using the formalinether concentration method combined with the acid-fast staining oocysts of Cryptosporidium were found in 7 (3 %) persons. 63 persons had contact to cattle, and asymptomatic cryptosporidiosis was diagnosed in 6 of them. Cryptosporidiosis was not found in any of the 51 persons with contact to some other animal but not cattle, and none of the 7 Cryptosporidium positive persons had been traveling abroad. We also obtained fecal samples from 15 calves from 7 households. Six of the calves (40 %) harbored Cryptosporidia and manifest enteritis was detected in those under age of 1 month. Five out of 14 farms had problems of neonatal calf diarrhea. Human cryptosporidiosis was more frequent on such problem farms. The results indicate that in rural population, human cryptosporidiosis is mainly asymptomatic and occurs mainly in residents of cattle-rearing farms.     

Calf-level risk factors for neonatal diarrhea and shedding of Cryptosporidium parvum in Ontario dairy calves

This work was conducted to investigate calf-level factors that influence the risk of neonatal diarrhea and shedding of Cryptosporidium parvum oocysts in calves, on dairy farms in Ontario with histories of calf diarrhea or cryptosporidiosis. Fecal samples were collected weekly for 4 weeks from each of 1045 calves under 30 days of age on 11 dairy farms in south-western Ontario during the summer of 2003 and the winter of 2004. A questionnaire designed to gather information on calf-level management factors was administered on farm for each calf in the study. Samples were examined for C. parvum oocysts by microscopy, and a subset of specimens was also tested for enterotoxigenic Escherichia coli, Salmonella, bovine rotavirus and bovine coronavirus. The consistency of each sample was scored and recorded at the time of collection in order to assess the presence or absence of diarrhea. In addition, a blood sample was taken from each calf upon enrollment in the study, for assessment of maternal antibody transfer and for polymerase chain reaction testing for persistent bovine viral diarrhea virus infection. Using the GLLAMM function in Stata 9.0, multilevel regression techniques were employed to investigate associations between management practices and the risk of C. parvum shedding or diarrhea. C. parvum oocysts were detected in the feces of 78% of the 919 calves from which all four fecal samples had been collected. Furthermore, 73% of the 846 calves for which all four fecal consistency scores had been recorded were diarrheic at the time of collection of at least one sample. Significant predictors of the calf-level risk of C. parvum shedding included the use of calf diarrhea prophylaxis in pregnant cows, and the type of maternity facilities in which the calves were born. Factors associated with an increased risk of diarrhea were leaving the calf with the dam for more than an hour after birth, and the birth of a calf in the summer as opposed to winter. Calves shedding C. parvum oocysts had 5.3 (95% CI 4.4, 6.4) times the odds of diarrhea than non-shedding calves, controlling for other factors included in the final multivariable model. Furthermore, infected calves shedding more than 2.2 x 10(5) oocysts per gram of feces were more likely to scour than infected calves shedding lower numbers of oocysts (OR= 6.1, 95% CI 4.8, 7.8). The odds of diarrhea in calves shedding oocysts that had been allowed to remain with their dams for more than an hour were higher than the odds of diarrhea in shedding calves that had been separated from their dams within an hour after birth.     

Enteric infections in veal calves: A longitudinal study on four veal calf units

Summary

Forty‐five calves on four veal calf units were monitored during the first four weeks after their arrival. Faecal samples were collected on alternate days and screened for the presence of rotaviruses, bovine coronavirus, Cryptosporidium oocysts, K99 positive strains of E. coli and Salmonella spp. Rotaviruses and Cryptosporidium were the most commonly detected agents (78% and 60% respectively of the calves). Bovine coronavirus was detected in the faeces of 18% of the calves, whilst K99 positive E. coli was only found in 2 samples from one calf. Salmonella spp. were not isolated from any of the 646 faecal samples examined. Shedding of rotaviruses occurred in a bimodal pattern beginning in the first week of the survey. Cryptosporidium oocysts were detected most frequently in the interval between the two peaks of rotavirus shedding. The presence of rotaviruses or Cryptosporidium oocysts in faeces was not strongly associated with scour, nor were combined infections with these agents or the cases of bovine coronavirus infection. The condition of the calves throughout the survey was generally satisfactory.