McCann Catherine M, Clough Helen E, Baylis Matthew, Williams Diana J L
Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.
Present address: Epidemiology Research Unit, Scotland's Rural College (SRUC), An Lòchran, Inverness Campus, Inverness, IV2 5NA, UK.
BMC Vet Res. 2018 Jun 15;14(1):185. doi: 10.1186/s12917-018-1511-3.
Liver fluke infection caused by the parasite Fasciola hepatica is a major cause of production losses to the cattle industry in the UK. To investigate farm-level risk factors for fluke infection, a randomised method to recruit an appropriate number of herds from a defined geographical area into the study was required. The approach and hurdles that were encountered in designing and implementing this study are described. The county of Shropshire, England, was selected for the study because of the variation between farms in exposure to fluke infection observed in an earlier study.
From a sampling list of 569 holdings in Shropshire randomly drawn from the RADAR cattle population dataset, 396 (69.6%) holdings were successfully contacted by telephone and asked if they would be interested in taking part in the study. Of 296 farmers who agreed to receive information packs by post, 195 (65.9%) agreed to take part in the study. Over the period October 2014 - April 2015 visits were made to 100 dairy and 95 non-dairy herds. During the farm visits 40 faecal samples +/- bulk-tank milk samples were collected and a questionnaire administered. Composite faecal samples were analysed for the presence of F. hepatica eggs by sedimentation and bulk tank milk samples were tested with an antibody ELISA for F. hepatica. Forty-five (49%) of non-dairy herds were positive for liver fluke infection as determined by the finding of one or more fluke eggs, while 36 (36%) dairy herds had fluke positive faecal samples and 41 (41%) dairy herds were positive for F. hepatica antibody. Eighty-seven (45.8%) farmers said that they monitored their cattle for liver fluke infection and 118 (62.1%) reported that they used flukicide drugs in their cattle.
Using a protocol of contacting farmers directly by telephone and subsequently sending information by post, 79% of the target sample size was successfully recruited into the study. A dataset of farm-specific information on possible risk factors for liver fluke infection and corresponding liver-fluke infection status was generated for the development of statistical models to identify risk factors for liver fluke infection at the farm-level.
由肝片吸虫寄生虫引起的肝吸虫感染是英国养牛业生产损失的主要原因。为了调查农场层面肝吸虫感染的风险因素，需要一种随机方法从特定地理区域招募适当数量的牛群参与研究。本文描述了在设计和实施该研究过程中遇到的方法和障碍。由于在早期研究中观察到不同农场在肝吸虫感染暴露方面存在差异，因此选择了英格兰什罗普郡进行该研究。
从RADAR牛群数据集随机抽取的什罗普郡569个养殖场的抽样清单中，通过电话成功联系到396个（69.6%）养殖场，并询问它们是否有兴趣参与研究。在296位同意通过邮寄方式接收信息包的农民中，195位（65.9%）同意参与研究。在2014年10月至2015年4月期间，对1百个奶牛场和95个非奶牛场进行了走访。在农场走访期间，收集了40份粪便样本以及散装储存罐牛奶样本，并进行了问卷调查。通过沉淀法分析混合粪便样本中是否存在肝片吸虫卵，并用肝片吸虫抗体酶联免疫吸附测定法检测散装储存罐牛奶样本。通过发现一个或多个吸虫卵确定，45个（49%）非奶牛场肝吸虫感染呈阳性，而36个（36%）奶牛场粪便样本吸虫呈阳性，41个（41%）奶牛场肝片吸虫抗体呈阳性。87位（45.8%）农民表示他们对牛群进行肝吸虫感染监测，118位（62.1%）报告称他们在牛群中使用了杀吸虫药物。
通过直接电话联系农民并随后邮寄信息的方案，成功招募了79%的目标样本量参与研究。生成了一个关于肝吸虫感染可能风险因素以及相应肝吸虫感染状况的农场特定信息数据集，用于开发统计模型以识别农场层面肝吸虫感染的风险因素。
