【猪译馆】人员入场隔离期多长时间最合适？（上）
译者的话：
人员入场隔离期多长时间合适？4晚、7天、14天？在即将来临的低价低利润养殖时期，任何成本的浪费或者冗余都会降低企业的竞争力，隔离期的长短不仅仅是劳务成本的增加，相应隔离设施、检测、物流成本也会增加。本实验在长达近四年观察监测期中，多角度的对比不同生物安全措施/等级和隔离期对蓝耳病（美国高致病性毒株）和气喘病传播的影响：14-16个小时的淋浴更衣换鞋+隔离是可以阻断蓝耳病毒和气喘病的传播的，累计45分钟的淋浴更衣换鞋隔离期在短期对比实验中也显示了有效性。此实验结果是对既往较长的隔离期的一种挑战，也是对包括非瘟在内其他疫病的隔离期的设定的一种思考，抛玉引玉，期待着国内有类似的研究信息共享。
同行评审
一晚的隔离时间可以防止猪繁殖和呼吸综合症病毒和猪肺炎支原体通过人员和污染物(靴子和工作服)传播（上）
A one-night downtime period prevents the spread of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae by personnel and fomites (boots and coveralls) - Part 1
作者 Authors
Andrea Pitkin, MS
Satoshi Otake, DVM, PhD
Scott Dee, DVM, MS, PhD, Diplomate ACVM
概要 Summary
本文总结了4年(1438天)的观察记录，关于一晚的隔离时间对防止猪繁殖和呼吸综合征病毒和猪肺炎支原体通过人员和污染物在猪群间机械传播的能力。
This paper summarizes observations recorded over a 4-year (1438-day) period regarding the ability of a 1-night period of downtime to prevent mechanical spread of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae between pig populations by personnel and fomites.
关键词：猪，猪繁殖和呼吸综合症，隔离，人员，污染物
Keywords: swine, porcine reproductive and respiratory syndrome, downtime, personnel, fomites
长时间限制与其他猪群接触过的人员进入养猪场的做法(隔离)是全球养猪业中一个极具争议的话题。多年来，尽管缺乏数据来支持这些隔离时间的科学性，但为了减少人员将病原体引入农场的风险，猪场都在实施从48小时到96小时不等的隔离时间。在文献中，Sellers[1]等人调查了人们接触感染猪只后携带口蹄疫病毒的能力。结果表明，在暴露后28小时，一个人的鼻拭子阳性，但在暴露后48小时，没有出现阳性。然而，尝试复制这些结果的并没有成功[2]。同样，Amass[3]等人报道，在接触感染猪5和24小时后，可分别从指甲冲洗和鼻拭子重获猪繁殖和呼吸综合征病毒(PRRSV) 的RNA。然而，在这些样本中PRRSV的生存能力没有被证实，也没有观察到传染阴性哨兵猪。最后，Otake[4]等人从接触感染动物的人员的手、靴子和工作服中重获了传染性的PRRSV病毒，并证明传染给了阴性哨兵猪。然而，这项研究还表明，在不考虑隔离的情况下，基本的卫生干预措施，如淋浴和更换衣服和鞋类，可以防止PRRSV的机械传播[4]。总之，这些数据对延长隔离时间的价值提出了挑战；因此，为了更好地理解这一风险，我们总结了关于一晚的隔离时间防止猪繁殖和呼吸综合症病毒(PRRSV)和猪肺炎支原体(Mhyo)通过人员和污染物(靴子和工作服)从感染猪群向易感猪群传播能力的观察。
The practice of restricting personnel entry to swine farms for extended periods of time following contact with other pigs (downtime) is a highly controversial subject throughout the global swine industry. For many years, downtime periods ranging from 48 to 96 hours have been enforced to reduce the risk of pathogen introduction to farms by personnel, despite a lack of data supporting these periods of time. In the literature, Sellers et al1 investigated the ability of people to harbor foot-and- mouth disease virus following exposure to infected swine. Results indicated the presence of one positive nasal swab from one person 28 hours post exposure, but not at 48 hours post exposure; however, attempts to replicate these results have not been successful.2 Likewise, Amass et al3 reported the recovery of porcine reproductive and respiratory syndrome virus (PRRSV) RNA from fingernail rinses and nasal swabs 5 and 24 hours, respectively, following contact with infected pigs; however, the viability of PRRSV in these samples was not confirmed and transmission to naive sentinels was not observed. Finally, Otake et al4 recovered infectious PRRSV from the hands, boots, and coveralls of personnel following contact with infected animals and demonstrated transmission to naive sentinels. However, this study also demonstrated that basic sanitary interventions such as showering and changing clothing and footwear could pre- vent mechanical spread of PRRSV, irrespective of downtime.4 Collectively, these data challenge the value of extended downtime periods; therefore, to better understand this risk, we summarized observations regarding the ability of a 1-night downtime period to prevent the mechanical spread of PRRSV and Mycoplasma hyopneumoniae (Mhyo) from infected to susceptible populations by personnel and fomites.
材料和方法
Materials and methods
设施 Facilities
我们的观察记录与一项为期4年（2006-2010）的PRRSV和Mhyo在猪疾病净化中心生产区域模型(明尼苏达州圣保罗)进行的区域传播和生物安全性评估相结合[5,6]。在本报告中，我们将重点关注在为期4年的区域传播和生物安全项目中使用的三个设施的活动：猪群本身、场内人员住所和高级别生物安全的猪舍(图1)。
Our observations were recorded in conjunction with a 4-year evaluation of area spread and biosecurity of PRRSV and Mhyo conducted at the Swine Disease Eradication Center Production Region Model (St Paul, Minnesota) over the period 2006-2010.5,6 For the purpose of this report, we will focus on activities that occurred in three facilities that were utilized throughout the 4-year area spread and biosecurity project: the source population, the on-site residence, and the high-level biosecurity building (Figure 1).
该猪群为300头25- 120公斤的猪只，这些猪只在1 - 4年内试验接种了PRRSV MN-184，在2 - 4内年试验接种了Mhyo菌株232[5,6]。这是一个持续流通的猪群，因此，在整个四年的研究期间，该设施从未被清空。新到的猪只，大约6到8周龄，每2到4周进入该设施，这取决于当前研究的实验设计[5,6]。新进猪只被放置在与现有猪群相邻的围栏中，允许鼻子对鼻子的接触，使得病原体从被感染的动物传播到未感染的动物。在整个研究过程中，记录了猪群呼吸系统疾病的临床症状以及PRRSV和Mhyo在猪群内的排毒情况，发现年死亡率为10% - 12% [5,6]。
The source population contained three hundred 25- to 120-kg pigs that had been experimentally inoculated with PRRSV MN-184 during years 1 to 4 and with Mhyo strain 232 during years 2 to 4.5,6 This was a continuous-flow population; therefore, the facility was never emptied during the entire 4-year study. New animals, approximately 6 to 8 weeks in age, entered this facility every 2 to 4 weeks depending on the experimental design of the current study.5,6 New animals were placed in pens adjacent to existing animals, allowing for nose-to-nose contact and circulation of pathogens from infected to naive animals. Throughout the course of the study, clinical signs of respiratory disease and shedding of PRRSV and Mhyo within the population were documented, and a 10% to 12% annual mortality was recorded.5,6
现场住所是猪病净化中心的一所房子，作为工作人员的淋浴进出设施，以及一处农场专用衣物的洗涤和鞋类的消毒场所。
The on-site residence was a house on the Swine Disease Eradication Center premises that served as a shower-in, shower-out facility for personnel and a site for washing farm-specific clothing and disinfection of farm-specific footwear.
最后，这个高级生物安全设施有10只猪，它们在整个项目期间无PRRSV和Mhyo感染。这一设施使用的是猪群全进全出原则；因此，第1年每2周一次(1年共26批猪)，第2 - 4年每4周一次(2 - 4年共39批猪)都有新一批猪进入。该设施的生物安全计划包括一系列经过科学验证的干预措施，针对PRRSV和Mhyo的所有直接和间接传播途径，包括一个空气过滤系统，旨在防止引入受PRRSV和Mhyo污染的生物气溶胶[5-7]。
Finally, the high-level biosecurity building was a swine facility which contained 10 animals naive for PRRSV and Mhyo throughout the project. This facility was operated using all-in, all-out pig-flow principles; therefore, new batches of animals entered every 2 weeks during year 1 (a total of 26 batches of pigs during year 1) and every 4 weeks during years 2 to 4 (a total of 39 batches of pigs across years 2 to 4). The biosecurity program for this facility consisted of a series of scientifically validated interventions for all direct and indirect routes of PRRSV and Mhyo transmission, including an air filtration system designed to prevent introduction of PRRSV- and Mhyo-contaminated bioaerosols.5-7
时间周期和活动事项
Time period and activities
同样，本着本报告的目的，我们将重点关注在为期4年的区域传播和生物安全项目中每天发生的三个具体事项周期：污染期、清洁和隔离期以及监测期。污染期大约每天发生在中央标准时间(CST)下午2点到4点之间。这段时间的目的是让研究人员接触受PRRSV和Mhyo感染的动物。在污染期间，工作人员进入该设施的所有11个大栏内，在那里他们饲喂动物、清理大栏地板、治疗病猪、移走死猪并完成必要的维修工作。在一个常规的工作日里，会有一到两个人进入每个设施。每个月，工作人员还标记并销售育肥猪，并对猪群进行抽样，以检测PRRSV和Mhyo的状态。每天污染期结束后，工作人员离开设施，并开始清洁和隔离期。
Again, for the purpose of this report, we will focus on three specific activity periods that occurred daily throughout the 4-year area spread and biosecurity project: the contamination period, the sanitation and downtime period, and the monitoring period. The contamination period occurred from approximately 2 pm to 4 pm Central Standard Time (CST) each day. The purpose of this period was to expose study personnel to PRRSV- and Mhyo-infected animals. During the contamination period, personnel entered all 11 pens in the source-population facility, where they fed animals, cleaned pen floors, treated sick pigs, removed dead animals, and completed necessary repair work. On an average working day, one or two people would have entered each facility. On a monthly basis, personnel also marketed finished animals and sampled the population to monitor its PRRSV and Mhyo status. Following completion of the contamination period each day, personnel left the facility and initiated the sanitation and downtime period.
清洁和隔离时间在污染期之后立即开始，大约从下午4点持续到第二天上午6点，中央标准时间(CST)。这个时期的目的是中和污染期的影响。在此期间，工作人员从猪场去往住所，在那里他们脱掉农场的衣服和鞋，洗澡，穿上自己的衣服和鞋子，并从当天下午大约4点到第二天早上大约6点避免与猪接触。用7%戊二醛和26%季铵盐(辛力加；国际保护协会，亚特兰大，乔治亚)对农用衣物和鞋类进行消毒。第二天中央标准时间(CST)大约早上5:30，工作人员再次洗澡，穿上干净的农场专用服装衣物和鞋子，进入高生物安全级别的设施内，开始监测阶段。
The sanitation and downtime period occurred immediately after the contamination period and ran from approximately 4 pm to 6 am CST. The purpose of this period was to neutralize the effects of the contamination period. During this period, personnel moved from the source population to the on-site residence where they removed farm clothing and footwear, took a shower, donned street clothing and footwear, and refrained from pig contact from approximately 4 pm that afternoon until approximately 6 am the next morning. Farm-specific clothing was washed and footwear was disinfected using 7% glutaraldehyde and 26% quaternary ammonium chloride (Synergize; Preserve International, Atlanta, Georgia). At approximately 5:30 am CST on the following day, personnel took another shower, donned clean farm-specific clothing and footwear, and entered the high-level biosecurity building for initiation of the monitoring period.
监测期是与该报告有关的第三个也是最后一个事项期，监测时间为每天中央标准时间(CST)上午6时至8时，在该高生物安全设施内进行。这个时期的目的是衡量在清洁和隔离期间所采用的做法的有效性。具体来说是测量两个结果：对人员进行PRRSV和Mhyo检测，以及检测设施中饲养的哨兵猪的PRRSV-Mhyo状态。清洁和隔离时间结束后，工作人员立即从住所前往距离约100米的高级别生物安全设施。进入设施专用接待室后，立刻进行拭子检查，以确定人员、衣物和鞋类上是否存在PRRSV RNA或Mhyo DNA。为了收集样本，涤纶拭子(Fisher Scientific, Hanover Park, Illinois)浸入含有3%胎牛血清的微量培养基(MEM)中(Difco, Detroit, Michigan)，并以“之”字型在每个人的头部、面部、颈部、躯干、手、手臂和腿上滑动擦拭。然后将拭子保存在-20℃的MEM中，直到收集后24 - 48小时进行实验室分析，以保持病毒完整性并最大化检测敏感性。取样后，穿上设施专用的靴子、工作服和手套，并用7%的戊二醛和26%的季铵盐对靴子进行消毒。工作人员随后进入猪群内，喂猪，打扫围栏。此外，每周对这10头猪进行健康诊断评估，包括对呼吸道疾病的临床症状进行目视观察，对所有10头猪进行血液检测和鼻腔擦拭。在采集之后，明尼苏达大学兽医诊断实验室(明尼苏达圣保罗MN VDL)通过聚合酶链反应(PCR)对人员、污染物和动物的所有样本进行了PRRSV RNA和Mhyo DNA的检测[8,9]。
The monitoring period was the third and final period pertaining to this report and occurred in the high-biosecurity building from approximately 6 am to 8 am CST each day. The purpose of this period was to measure the efficacy of the practices utilized during the sanitation and downtime period. Specifically, two outcomes were measured: detection of PRRSV and Mhyo on personnel and the PRRSV-Mhyo status of sentinel animals housed in the facility. Upon completion of the sanitation and downtime period, personnel moved immediately from the on-site residence to the high-level biosecurity building, a distance of approximately 100 m. Upon entry into the facility-specific anteroom, a swabbing protocol, designed to determine if PRRSV RNA or Mhyo DNA was present on personnel, clothing, and footwear, was conducted.5,6 For collection of samples, Dacron swabs (Fisher Scientific, Hanover Park, Illinois) were immersed in minimal essential medium (MEM) supplemented with 3% fetal calf serum (Difco, Detroit, Michigan) and swiped using a zigzag pattern across each person’s head, face, neck, torso, hands, arms, and legs. Swabs were then stored in MEM at -20°C to maintain viral integrity and maximize testing sensitivity until laboratory analysis could be conducted 24 to 48 hours post collection. Following sampling, facility-specific boots, coveralls, and gloves were donned and boots were disinfected using 7% glutaraldehyde and 26% quaternary ammonium chloride. Personnel then entered the animal air space, fed pigs, and cleaned pens. In addition, on a weekly basis, a diagnostic assessment of the health of this 10-pig population was conducted, involving visual observation of clinical signs of respiratory disease and blood testing and nasal swabbing of all 10 pigs. Immediately following collection, all samples from personnel, fomites, and animals were tested for PRRSV RNA and Mhyo DNA by polymerase chain reaction (PCR) at the University of Minnesota Veterinary Diagnostic Laboratory (MN VDL, St Paul, Minnesota).8,9