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奶牛场传染性生物因子风险控制Center for Food Security and Public Health Iowa State University 2006
奶牛场传染性生物因子风险控制
中国兽医药品监察所
毛开荣
什么是风险控制
风险控制是指风险管理者采取各种措施
和方法,消灭或减少风险事件发生的各种可能
性,或者减少风险事件发生时造成的损失._
奶牛场传染性生物因子风险控制
主要内容
首先要了解可能发生的奶牛场传染性生物因子
通过评估确定这些因子的风险程度
以科学的设计和管理达到控制风险的目的
第一步
了解
奶牛场传染性生物因子风险
影响了解风险因子的因素
不重视认识风险是风险最大根源
经验和知识对了解风险启着重要作用
直接的经验可以从实践中获得.
更多的是间接经验,来自学习.
理论知识对认识了解风险具有指导性作用.
风险可能是多样化的
需要根据具体情况进行分析
同一个因子在不同奶牛场风险程度可能不一样
同一个奶牛场在不同时间风险程度可能不一样
…
影响了解风险因子的因素
风险可能是多样化的
需要根据具体情况进行分析
同一个因子在不同奶牛场风险程度可能不一样
同一个奶牛场在不同时间风险程度可能不一样
…
影响了解风险的因素
常见的误区是不从风险评估角度着眼
"我们一直怎么做的"
"我们已经做得差不多了"
"太贵了"
…
应该树立的观念
疫病随时可能发生
预防比发生后处理更经济
避免财经投入过少
在明了的基础上才能有效预防控制
奶牛场传染性生物因子遍布全世界
奶牛场传染性因子不可能完全消除
动物生存的环境存在多种传染性因子
国际兽医局(0IE)《动物卫生法典》中牛的重大疫病包括:
包括:
1,结核病;2,布氏杆菌病;3,口蹄疫;4,炭疽;5,狂犬病;6,牛海绵状脑病;7,牛病毒性腹泻;8,牛传染性鼻气管炎;9,牛巴贝斯虫病;10牛无浆体病;11,牛恶性卡他热;12,流行性牛白血病;13,牛传染性胸膜肺炎;14牛出血性败血病;15,牛生殖道弯杆菌病;16,疙瘩皮肤病;17,毛滴虫病;18,锥虫病;19,泰勒氏虫病等.
我国牛的重大疫病
《中华人民共和国动物防疫法》,按照疫病危害程度,将动物疫病分为一,二,三类.
一类牛传染病4种:口蹄疫,牛瘟,牛传染性胸膜肺炎(牛肺疫),牛海绵状脑病;
二类牛传染病17种:伪狂犬病,狂犬病,炭疽,魏氏梭菌病,副结核病,布鲁氏菌病,弓形虫病,棘球蚴病,钩端螺旋体病,牛传染性鼻气管炎,牛恶性卡他热,牛白血病,牛出血性败血病,牛结核病,牛焦虫病,牛锥虫病,日本血吸虫病等;
三类牛传染病包括:黑腿病,李氏杆菌病,类鼻疽,放线菌病,肝片吸虫病,丝虫病,牛流行热,牛病毒性腹泻/粘膜病,牛生殖器弯曲菌病,毛滴虫病,牛皮蝇蛆病.等
奶牛新发和再发传染病的风险
新发传染病
可以是世界范围内未发现过的,也可以是某地区以前未发生过的危害严重的疫病.
新发传染病,传播迅速,在较大范围导致动物很高的发病率或(和)死亡率.
或(和)具有明显的人畜共患病特征.
再发传染病
指以前未发生过的危害严重的疫病.
可以是世界范围内,也可以是某地区曾经控制或危害降低了的疫病.又出现新的严重传播危害.
新发和再发传染病风险
2005年
禽流感H5N1扩散到欧洲,非洲.
中国爆发猪链球菌病.
2004年
禽流感在亚洲爆发.
2003年
SARS病毒在中国肆虐.
猴痘病毒在美国流行.
1999年
美国发现西尼罗河病毒.
1998年
Nipah病毒在马来西亚感染猪和人.
1997年
香港发生首例人禽流感.
1996
在英国发现人的新变异型克雅氏病(vCJD).
1993年
美国发现汉坦(Hanta)病毒.
1986年
英国发现首例疯牛病.
1983年
美国发现艾滋病病毒(HIV) .
1982年
美国首次发现大肠杆菌O157引起的食物中毒.
莱姆病的病原体在美国被分离出.
一些人畜共患病原具有高度风险性
与动物接触的畜牧业生产者
需要进行有关防控知识培训
必要是应进行免疫预防
特殊人群要特殊对待
免疫缺陷的病人更容易受到人畜共患病侵害
化疗
糖尿病
主要奶牛人畜共患病
疯牛病,牛结核病,牛布鲁氏病,牛隐孢子虫病,牛新孢子虫病,牛球虫病.…
奶牛与产品的贸易带来的传染性生物因子传播风险
贸易有利生物危害因子的传播
人工导致传染病患病动物及携带传染性生物因子产品的转移
牛和动物产品的引进
患病动物不一定有症状
易感动物的出现
奶牛场重点了解的风险信息
1,了解引进奶牛的风险
引进奶牛地的疫病状况
流行什么疫病;是否有本地未出现过的疫病
免疫,检疫等情况
免疫,检疫(包括监测等防控措施)的计划与档案;
管理,资质等情况
管理水平,外界评定(权威机构)等情况.
运输过程的风险
是否经过疫区,可能的隔离程度.…
奶牛场重点了解的风险信息
2,了解其它动物进入奶牛场的风险
避免饲养宠物及其它家畜等动物
宠物,家畜等可能带有共患病,如布病,结核.
防止野生动物进入
有些疫病具有自然疫源性,如炭疽.
了解媒介动物
如牛焦虫病是由蜱为媒介而传播的.
奶牛场重点了解的风险信息
3,奶牛场进入人员的风险了解
对员工进行健康检查与平时监测
定期卫生检查,重点在人畜共患病,如结核病.
了解平时携带传染因子可能性.如自家是否饲养动物,动物健康状况,与奶牛场外动物或产品接触情况等.
限制外来人员的进入
尤其是与动物有频繁接触的人员.
人员进入的防护
对奶牛场环境的保护.
对人员的防护.
奶牛场重点了解的风险信息
4,了解物品进入奶牛场的风险
饲料
产地的疫病流行情况
车辆
消毒
…
奶牛场重点了解的风险信息
5,周围环境风险了解
疫病流行情况
针对流行采取免疫措施
针对性的消毒
针对性的防护隔离
第二步
评估
奶牛场传染性生物因子风险
认识奶牛场传染性生物因子风险
控制的重要性
奶牛业在国民经济中的重要作用体现在哪儿
1,奶牛产业在农业经济中占有相当大的比例
发达国家畜牧业产值占农业生产总值的60以上,其中奶牛业占畜牧业的50以上.
我国畜牧业产值占农业生产总值的比例已经达到25%以上.
虽然我国奶牛业只占畜牧业产值的10% ,但在不断发展.
中国奶牛业还在不断增长
奶牛业在国民经济中的重要作用体现在哪儿
2,提供大量的就业岗位
在我国,一头养殖奶牛,其形成的产业链可以提供1.2个就业岗位.
2006年,我国约有奶牛1300万头,意味着提供了1560万个就业岗位.
奶牛业在国民经济中的重要作用体现在哪儿
3,对解决三农问题有重要作用
我国奶牛养殖当前主要发展地在农村,大部分的奶牛由农民饲养.
风险评估对象
引进动物,动物产品,动物遗传物质
饲料,特别是动物源性饲料
生物制品和动物病理材料存在危害因素的.
根据需要,对输出地的动物卫生和公共卫生体系进行评估.
风险评估过程
传入评估
评价风险传入的可能性
发生评估
评价引进动物等发生疫病的可能性
后果评估
发生后的危害程度
风险预测
根据上述评估,进行综合分析,获得风险预测结果.
包括
传入评估应当考虑以下因素:
(一)生物学因素
易感因素:
如动物种类,年龄,品种等.
病原因素:
病原流行种类,严重程度等.
对方的管理因素
免疫,检疫,监测,处理,卫生等管理技术,措施,规划…;
传入评估应当考虑以下因素:
(二)对方管理因素
对疫病控制的政策
动物卫生和公共卫生体系要求
危害因素的监控计划和区域化措施
传入评估应当考虑以下因素:
(三)商品因素
如引进数量,减少污染的措施,加工过程的影响,贮藏和运输的影响.
发生评估应当考虑的因素:
(一)生物学因素
如易感动物,病原性质等;
(二)国家因素
如传播媒介,人和动物数量,文化和习俗,地理,气候和环境特征;
(三)商品因素
如进境商品种类,数量和用途,生产加工方式,废弃物的处理.
后果评估应当考虑以下因素:
(一)直接后果
如动物感染,发病和造成的损失,以及对公共卫生的影响等;
(二)间接后果
如危害因素监测和控制费用,补偿费用,潜在的贸易损失,对环境的不利影响.
风险预测
对传入评估,发生评估和后果评估的内容综合分析.
作出风险预测.
第三步
管理
奶牛场传染性生物因子风险
风险了解和风险评估是风险管理的基础
要根据风险评估的结果,确定与奶牛场适当保护水平相一致的风险管理措施.
风险管理是制定计划和采取措施降低损失的可能性,或者是减少实际损失.
制定风险管理措施,要注意有效性和可行性.
风险管理_
管理包括事前,事中和事后三个阶段.
事前控制的目的主要是为了降低损失的概率,
事中和事后控制主要是为了减少实际发生的损失.
风险管理的基本形式
风险回避,风险转移,风险保留
风险回避_
风险回避是主体有意识地放弃风险行为,可以完全避免特定的损失风险.
出现以下情况,可以采用这种方法:_
(1)主体无能力消除或转移风险,出现风险无能力承担该
或_得不到足够的补偿.
(2)存在可实现同样目标的其他方案.
风险转移
是指通过契约,将风险部分或全部转移给受让人承担的行为.
风险转移的主要形式是契约和保险.
(1)契约转移.
通过签订合同,可以将部分或全部风险转移给一个或多个其他参与者.如公司加养殖场的模式.
通过参加契约组织,有组织共同承担全部或部分风险.如参加行业协会等.
(2)保险转移.
保险是国外使用最为广泛的风险转移方式._
(3)其它形式转移.
如财政补贴等.
4,风险保留
即风险自负.一般来说,如果损失发生,经济主体应有能力承担,否则应考虑其它方式以减低风险程度.
风险保留包括无计划自留,有计划自我保险.
(1)无计划自留.
指风险损失发生后从收入中支付,即不是在损失前做出资金安排.
一般来说,无资金保留应当谨慎使用,因为如果实际总损失远远大于预计损失,将引起资金周转困难.
(2)有计划自我保险.
指可能的损失发生前,通过做出各种资金安排以确保损失出现后能及时获得资金以补偿损失.
有计划自我保险主要通过建立风险预留基金的方式来实现._
风险管理程序
首先进行可行性评价
制定精细的管理规划
区别先后,考虑难易程度,考虑经济效益,特殊情况.
管理规划实施的反馈
直接挑战,短期目标,长期目标.
持续性解决问题
获取建议
建议非常有赖于经验和知识
风险管理常规内容
严格的隔离措施
牛场范围,围栏,门卫要严格把关
限制动物间的接触
相邻动物,野生动物(包括鸟类),流浪猫,狗
…
有效的动物卫生制度
环境,用具,饲料,人员等卫生规定
为人员,车辆制定生物安全规定
非传染性病,死动物处理.
新生动物卫生管理尤其重要
…
风险管理常规内容
动物标识
具有非常重要的作用:
健康信息,处理要求
在牛场中的位置,档案
每头动物要有健康记录
风险管理常规内容
犊牛要在出生后6小时内摄取足够的初乳
防止与大牛和污染环境接触
员工培训
发现和报告患病动物
每天检查动物健康状况
及时清理器械,用具,服装
立即隔离病畜
隔绝空气流通, 避免与其它动物接触
风险管理重点
传染源管理
传播途径管理
易感动物管理
易感动物管理
新进动物检疫,免疫
包括新购买的,重新回归的要隔离检疫.
根据评估选择使用疫苗免疫.
兽医根据实际情况作出隔离,检疫,免疫方案,尤其要注意重大疫病.
注意预防和检疫用疫苗,试剂的有效性
使用者要经过有关的培训
易感动物管理
要制定免疫预防规划
制定年度或半年性规划
规划要针对实际情况
对非正常现象及时调查
神经症状, 猝死, 暴死…
迅速和恰当地处理病畜
淘汰和无害化处理
检验以了解病因
传染源管理
确定要避免哪些传染源进入奶牛场
重大动物疫病,重要人畜共患病等
认真实施风险评估,以达到避免引进不可接受传染源的危险
传播途径管理
需要了解所有的传播途径
了解不同感染途径= 获得控制
以便为家畜养殖制定出使疫病风险降低到尽可能小的程度
针对经过评估的传染性因子
确认风险范围,对象…
设计好管理方案,以使得感染的可能性最小化.
传播途径
传染因子的扩散
动物 到 动物
动物 到 人
各种传播途径
气溶胶
直接接触
污染物
消化道
媒介传播
人畜共患
气溶胶传播
传染因子附着在雾滴上
通过空气传播
气溶胶一般情况下不稳定
只能近距离传播
有效传播距离内有易感动物
直接接触传播
环境中存在传染因子
开放的疮口, 粘膜,皮肤
血液,唾液, 面对面, 磨蹭,撕咬
传染因子的复制
饲养
母兽和子代
污染物传播
污染非生命物质
刷子,针
携带传染因子到易感动物
交易
交通工具
人类
消化道
消化道传染
饲料, 水
粪便,尿,唾液
其它污染
(反刍物)
舔/咀嚼
污染
环境
媒介传染
昆虫
从病畜获得病原
传染给其它动物
跳蚤, 扁虱, 蚊子
苍蝇, 蟑螂
环境污染
环境中病原
土壤中存活的病原, 器官组织
动物和人可从以下途径感染环境中病原
吸入
直接接触
污染物
口入
媒介
谢谢
In this overview presentation, we will introduce the concept of biological risk management (BRM) and discuss how it applies to beef and dairy producers.
Biological risk management is the overall process of awareness education regarding the risk of infectious diseases entering or spreading through an animal facility. It also involves evaluating and managing those risks. BRM is designed to help livestock producers understand the need for disease control, not only for foreign animal disease threats but domestic diseases as well. Biological risk management provides the tools to minimize the risk (photo courtesy of: DB Weddle).
Risk means different things to different people. It is imperative to first identify what those involved with the operation think about the real and potential risks of infectious and zoonotic diseases. The public often relies heavily on previous experience, the media, and their environment. What risks are deemed acceptable or tolerable also varies between individuals. The inset photo demonstrates the attention directed toward the first US case of BSE in 2003 (source CNN).
Risk means different things to different people. It is imperative to first identify what those involved with the operation think about the real and potential risks of infectious and zoonotic diseases. The public often relies heavily on previous experience, the media, and their environment. What risks are deemed acceptable or tolerable also varies between individuals. The inset photo demonstrates the attention directed toward the first US case of BSE in 2003 (source CNN).
This is also the period where one may encounter many of the obstacles and challenges to educating about risk management. Common negative beliefs include: "I already know this stuff", "We have always done it this way", "I''ve already had most everything on this farm", "I don''t have enough time to mess with this", "It''s too expensive", and "Our animals were tested once and we found nothing, it was just a waste of money".
While it is difficult to prove and measure the benefit of things that don''t happen, counter-arguments tend to fall into three categories: there is a risk, it is economically worthwhile to prepare, and the overall impact must be considered. Some beliefs that may require a change of mindset include: "Infectious/zoonotic disease outbreaks can and do happen", "Prevention is less costly than treatment", "Protecting your financial investment and your future assets from liability is worthwhile insurance" and of increasing importance is the "Prevention of disease through awareness and management".
BRM recognizes that diseases cannot be eliminated, but that the risk can be managed through effective control measures. As animal caretakers, it is our duty to be knowledgeable of the animal and its environment to minimize the risk of disease._For_nearly all_diseases there is a relationship between dose exposure and severity of disease._For diseases that are always present (endemic), reducing the dose of infectious agent the animal is exposed to can positively affect the farm''s economic impact and help justify the cost of implementing BRM. Many different solutions exist and because all cattle facilities are different, there is not a one-size-fits-all answer. Photo depicts cattle in a pasture and the owner walking through them monitoring for illness (courtesy of USDA, taken by Bill Tarpenning).
Livestock producers have a lot of contact on a daily basis with animals. In most cases associated with infectious diseases, the farmer has been previously exposed and has developed some type of immunity to it. This is not the case with foreign animal diseases or if their health becomes compromised because normal diseases could make them ill. This immunocompromised population is more vulnerable to zoonotic diseases, those that are spread from animals to humans. Immunocompromised individuals include the elderly, children under the age of 5, pregnant women, chemotherapy patients, organ transplant recipients, persons with HIV/AIDS, and people with chronic diseases such as diabetes. This makes disease awareness imperative. The top photo shows an elderly farmer, while the bottom photo shows another susceptible population, an immunocompromised person in a nursing home (photo sources USDA).
Let us begin our discussion by addressing the importance of biological risk management.
Let us begin our discussion by addressing the importance of biological risk management.
Let us begin our discussion by addressing the importance of biological risk management.
Once a facility or operation has been evaluated, the challenges to implementing a successful BRM plan can be identified. Only then can a tailored management plan be proposed and implemented. When first working on change, prioritize those items that are relatively easy to implement, inexpensive, yet yield rewards. There is no common formula for what that entails, and rewards will be different for everyone. Simply reducing exposure could be beneficial. The photo shows a large feedlot in Texas (photo source DB Weddle).
There are many general prevention steps that every farm could implement that would help prevent against a variety of diseases that are transmitted in various ways. Things such as knowing what is in the area of your farm perimeter- farms, neighboring livestock, wildlife; individual animal identification, animal health protocols, recognizing and dealing with sick and dead animals, isolation/quarantine, supply handling, and neonatal management. This next section will provide some general prevention recommendations for those areas. Note to presenter: This next section will review general prevention practices; this is where you could hand out the General Prevention Practices document and Checklist to the audience and have them follow along. The checklist can be taken home so they can evaluate their own operation.
If more than one person works on an operation, individual animal identification is imperative for proper communication of health status, treatment needs, antibiotic withdrawal/residue prevention status, and location on farm. Individual animal identification is imperative to proper record keeping (vaccinations, treatments, pregnancy status) which is an integral part of managing animals and minimizing disease risk on farm. Keeping treatment records is an integral part of minimizing disease risk on farm because protocols can be tracked over time with your veterinarian and used to determine whether things are working in various disease situations. If these black Angus heifers did not have identification tags in their ears, it would be hard to communicate health status to someone else because they all look alike (photo source: DB Weddle, ISU).
Adequate ingestion of colostrum is the most important consideration for calf''s resistance to disease and all calves should receive colostrum within 6 hours of birth. A calf''s immune system depends on the antibodies in colostrum. After 6 hours of life, the calf''s ability to absorb antibodies from colostrum diminishes. Once a calf is born, subsequent milk production in the cow will dilute colostrum and therefore require the calf to consume more for maximum antibody absorption and immune function. Another good practice is to prevent contact of the neonate with older animals and also contaminated environments. This will decrease the pathogen load to the newborn and give the colostrum the ability to provide protection. The photo depicts colostrum in a freezer that is stored in palpation sleeves (with the fingers tied off), labeled with the cow ID number and dated. This allows for easy thawing and making sure the calf gets colostrum from one cow (photo courtesy of DB Weddle).
Cattle that are identified as ill should be removed from the rest of the herd immediately and placed in an isolation area where ventilation, feed/water, and other equipment are not shared and direct contact with other animals does not occur in order to minimize the risk of disease spread. Newly introduced animals, including show cattle/calves that have been away from the farm, may be carrying diseases that your home herd is not immune to, so quarantine them for a period of time. Time spent in isolation and quarantine varies depending on the risk so this should be determined together with your herd veterinarian. Before taking animals out of isolation or quarantine, it is a good risk management plan to test them for key diseases (determined together with your herd veterinarian) and make sure they are not carrying diseases that could be introduced into the home herd.
To monitor health status, it is imperative to keep health records on every animal. There are many computer programs out there that can simplify this for producers as the photo depicts (courtesy of Dale Moore, UC Davis VMTRC). It is important to work with your clients to review treatment and vaccination records so alterations can be made to the animal health protocols on farm; this will also help ensure what you think is happening is actually happening. Producers should work with their veterinarian to investigate those animals that present with unusual symptoms or are unresponsive to treatment, especially neurologic cases, downers and those that die suddenly.
To monitor health status, it is imperative to keep health records on every animal. There are many computer programs out there that can simplify this for producers as the photo depicts (courtesy of Dale Moore, UC Davis VMTRC). It is important to work with your clients to review treatment and vaccination records so alterations can be made to the animal health protocols on farm; this will also help ensure what you think is happening is actually happening. Producers should work with their veterinarian to investigate those animals that present with unusual symptoms or are unresponsive to treatment, especially neurologic cases, downers and those that die suddenly.
The approach that was taken in the development of these biological risk management tools was to look at diseases based on their route of transmission to the animal, or human in the case of zoonotic diseases. An advantage of minimizing risk by examining routes of transmission is that it will also help protect against new or unanticipated infectious diseases. While disease agents and the infections they produce vary, they all have one thing in common: the animal must be exposed to them to develop disease. Once it is understood that different diseases can be acquired orally and others are breathed in via aerosol transmission, it is easier to gain control over them. This classification system is effective and easy to understand without requiring knowledge about a wide range of diseases. From a management standpoint, it may be easier to identify risk areas, such as fomites, and then design protocols to minimize exposure.
Disease agents can be spread from animal to animal, or animal to human, through a variety of transmission routes. For the purposes of the biological risk management materials, 5 main routes were identified: aerosol, direct contact, fomite, oral and rector-borne. The sixth route, zoonotic, can be spread from animals to humans through one of the 5 previously listed routes. Many infectious agents can be transmitted by more than one route of infection. This photo shows several dairy cows grazing in a pasture (photo source USDA – ARS). Note to presenter: This next section will review each route of transmission; this is where you could hand out the Transmission Route Definitions handout to the audience and have them follow along.
Aerosol transmission occurs when disease agents contained in droplets are passed through the air from one animal to another, or animal to human. Most pathogenic agents do not survive for extended periods of time within the aerosol droplets, and as a result, close proximity of infected and susceptible animals is required for disease transmission. Top photo depicts a tunnel ventilated dairy building; aerosol transmission is of concern if not properly ventilated (photo source DB Weddle). The bottom photo shows a situation where cattle are always in close proximity to one another- a feedlot (photo source USDA).
Transmission by direct contact requires the presence of an agent or organism in the environment or within an infected animal. A susceptible animal becomes exposed when the agent directly touches open wounds, mucous membranes, or the skin through blood, saliva, nose to nose contact, rubbing or biting. It is important to note that depending on the disease agent, it is possible for direct contact transmission to occur between animals of different species as well as to humans. For the purposes of the BRM information, reproductive transmission will encompass those diseases spread through venereal and in-utero routes. Venereal transmission (breeding), a type of direct contact, is the spread of pathogenic agents from animal to animal through breeding. In-utero (dam to offspring) transmission, another type of direct contact, is the spread of pathogenic agents from dam to offspring during gestation. The top photo shows a group of calves together in a pen with ample opportunities for direct contact transmission (photo source DB Weddle, ISU). The bottom photo shows a young heifer licking her newborn calf (photo source USDA).
A fomite is an inanimate object that can carry disease agents from one susceptible animal to another. Examples of fomites include contaminated brushes, clippers, needles, balling guns (middle picture; photo source DB Weddle) clothing, milking units, teat dip cups, feed or water buckets, and shovels. The top photo depicts a situation in which disease transmission may occur via a fomite, grooming equipment (photo source USDA). Traffic transmission is another special type of fomite transmission in which a vehicle, trailer, or human spreads organic material to another location. The bottom photos show the entrance to a dairy with a sign stating the premise''s visitor restrictions, as well as a handy place for boot distribution and collection at the entrance to the farm (photos source DB Weddle).
Pathogenic agents can also be transmitted to animals or humans orally through consumption of contaminated feed, water or licking/chewing on contaminated environmental objects. Feed and water contaminated with feces, urine or saliva are frequently the cause of oral transmission of disease agents. However, feed and water can be contaminated with other infectious agents as well such as ruminant protein in ruminant feed. The top photo depicts a Holstein and an Ayrshire drinking from different sides of a water tank- if it becomes contaminated, all of the animals in those pens could be exposed (photo courtesy of DB Weddle, ISU). The bottom depicts Hereford calves eating silage at a wooden feed bunk, a potential source of bird, rodent, or dog contamination (photo source USDA).
Vector-borne transmission occurs when an insect acquires a pathogen from one animal and transmits it to another. Fleas, ticks, and mosquitoes are common biological vectors of disease, and flies and cockroaches are a common mechanical vector. The top photo shows a calf with two old insecticide ear tags and numerous face flies, while the bottom photo shows an adult deer tick, Ixodes scapularis capable of spreading Lyme disease (photo source USDA).
Many disease agents can survive for extended periods of time in soil or other organic material like bedding, old feed, etc. Animals or humans can then acquire the disease agent from the environment through inhalation or aerosolization, oral consumption, direct contact, or via fomites as discussed in previous slides. Therefore, environmental contamination should not be ignored but recognize the routes it uses to get into the animal can be controlled. This photo demonstrates the wide realm of environmental contamination possibilities (photo source DB Weddle).
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·上一篇：非传染性疾病
·下一篇：国家过敏及传染性疾病研究所与国家卫生研究所
奶牛场传染性生物因子风险控制
中国兽医药品监察所
毛开荣
什么是风险控制
风险控制是指风险管理者采取各种措施
和方法,消灭或减少风险事件发生的各种可能
性,或者减少风险事件发生时造成的损失._
奶牛场传染性生物因子风险控制
主要内容
首先要了解可能发生的奶牛场传染性生物因子
通过评估确定这些因子的风险程度
以科学的设计和管理达到控制风险的目的
第一步
了解
奶牛场传染性生物因子风险
影响了解风险因子的因素
不重视认识风险是风险最大根源
经验和知识对了解风险启着重要作用
直接的经验可以从实践中获得.
更多的是间接经验,来自学习.
理论知识对认识了解风险具有指导性作用.
风险可能是多样化的
需要根据具体情况进行分析
同一个因子在不同奶牛场风险程度可能不一样
同一个奶牛场在不同时间风险程度可能不一样
…
影响了解风险因子的因素
风险可能是多样化的
需要根据具体情况进行分析
同一个因子在不同奶牛场风险程度可能不一样
同一个奶牛场在不同时间风险程度可能不一样
…
影响了解风险的因素
常见的误区是不从风险评估角度着眼
"我们一直怎么做的"
"我们已经做得差不多了"
"太贵了"
…
应该树立的观念
疫病随时可能发生
预防比发生后处理更经济
避免财经投入过少
在明了的基础上才能有效预防控制
奶牛场传染性生物因子遍布全世界
奶牛场传染性因子不可能完全消除
动物生存的环境存在多种传染性因子
国际兽医局(0IE)《动物卫生法典》中牛的重大疫病包括:
包括:
1,结核病;2,布氏杆菌病;3,口蹄疫;4,炭疽;5,狂犬病;6,牛海绵状脑病;7,牛病毒性腹泻;8,牛传染性鼻气管炎;9,牛巴贝斯虫病;10牛无浆体病;11,牛恶性卡他热;12,流行性牛白血病;13,牛传染性胸膜肺炎;14牛出血性败血病;15,牛生殖道弯杆菌病;16,疙瘩皮肤病;17,毛滴虫病;18,锥虫病;19,泰勒氏虫病等.
我国牛的重大疫病
《中华人民共和国动物防疫法》,按照疫病危害程度,将动物疫病分为一,二,三类.
一类牛传染病4种:口蹄疫,牛瘟,牛传染性胸膜肺炎(牛肺疫),牛海绵状脑病;
二类牛传染病17种:伪狂犬病,狂犬病,炭疽,魏氏梭菌病,副结核病,布鲁氏菌病,弓形虫病,棘球蚴病,钩端螺旋体病,牛传染性鼻气管炎,牛恶性卡他热,牛白血病,牛出血性败血病,牛结核病,牛焦虫病,牛锥虫病,日本血吸虫病等;
三类牛传染病包括:黑腿病,李氏杆菌病,类鼻疽,放线菌病,肝片吸虫病,丝虫病,牛流行热,牛病毒性腹泻/粘膜病,牛生殖器弯曲菌病,毛滴虫病,牛皮蝇蛆病.等
奶牛新发和再发传染病的风险
新发传染病
可以是世界范围内未发现过的,也可以是某地区以前未发生过的危害严重的疫病.
新发传染病,传播迅速,在较大范围导致动物很高的发病率或(和)死亡率.
或(和)具有明显的人畜共患病特征.
再发传染病
指以前未发生过的危害严重的疫病.
可以是世界范围内,也可以是某地区曾经控制或危害降低了的疫病.又出现新的严重传播危害.
新发和再发传染病风险
2005年
禽流感H5N1扩散到欧洲,非洲.
中国爆发猪链球菌病.
2004年
禽流感在亚洲爆发.
2003年
SARS病毒在中国肆虐.
猴痘病毒在美国流行.
1999年
美国发现西尼罗河病毒.
1998年
Nipah病毒在马来西亚感染猪和人.
1997年
香港发生首例人禽流感.
1996
在英国发现人的新变异型克雅氏病(vCJD).
1993年
美国发现汉坦(Hanta)病毒.
1986年
英国发现首例疯牛病.
1983年
美国发现艾滋病病毒(HIV) .
1982年
美国首次发现大肠杆菌O157引起的食物中毒.
莱姆病的病原体在美国被分离出.
一些人畜共患病原具有高度风险性
与动物接触的畜牧业生产者
需要进行有关防控知识培训
必要是应进行免疫预防
特殊人群要特殊对待
免疫缺陷的病人更容易受到人畜共患病侵害
化疗
糖尿病
主要奶牛人畜共患病
疯牛病,牛结核病,牛布鲁氏病,牛隐孢子虫病,牛新孢子虫病,牛球虫病.…
奶牛与产品的贸易带来的传染性生物因子传播风险
贸易有利生物危害因子的传播
人工导致传染病患病动物及携带传染性生物因子产品的转移
牛和动物产品的引进
患病动物不一定有症状
易感动物的出现
奶牛场重点了解的风险信息
1,了解引进奶牛的风险
引进奶牛地的疫病状况
流行什么疫病;是否有本地未出现过的疫病
免疫,检疫等情况
免疫,检疫(包括监测等防控措施)的计划与档案;
管理,资质等情况
管理水平,外界评定(权威机构)等情况.
运输过程的风险
是否经过疫区,可能的隔离程度.…
奶牛场重点了解的风险信息
2,了解其它动物进入奶牛场的风险
避免饲养宠物及其它家畜等动物
宠物,家畜等可能带有共患病,如布病,结核.
防止野生动物进入
有些疫病具有自然疫源性,如炭疽.
了解媒介动物
如牛焦虫病是由蜱为媒介而传播的.
奶牛场重点了解的风险信息
3,奶牛场进入人员的风险了解
对员工进行健康检查与平时监测
定期卫生检查,重点在人畜共患病,如结核病.
了解平时携带传染因子可能性.如自家是否饲养动物,动物健康状况,与奶牛场外动物或产品接触情况等.
限制外来人员的进入
尤其是与动物有频繁接触的人员.
人员进入的防护
对奶牛场环境的保护.
对人员的防护.
奶牛场重点了解的风险信息
4,了解物品进入奶牛场的风险
饲料
产地的疫病流行情况
车辆
消毒
…
奶牛场重点了解的风险信息
5,周围环境风险了解
疫病流行情况
针对流行采取免疫措施
针对性的消毒
针对性的防护隔离
第二步
评估
奶牛场传染性生物因子风险
认识奶牛场传染性生物因子风险
控制的重要性
奶牛业在国民经济中的重要作用体现在哪儿
1,奶牛产业在农业经济中占有相当大的比例
发达国家畜牧业产值占农业生产总值的60以上,其中奶牛业占畜牧业的50以上.
我国畜牧业产值占农业生产总值的比例已经达到25%以上.
虽然我国奶牛业只占畜牧业产值的10% ,但在不断发展.
中国奶牛业还在不断增长
奶牛业在国民经济中的重要作用体现在哪儿
2,提供大量的就业岗位
在我国,一头养殖奶牛,其形成的产业链可以提供1.2个就业岗位.
2006年,我国约有奶牛1300万头,意味着提供了1560万个就业岗位.
奶牛业在国民经济中的重要作用体现在哪儿
3,对解决三农问题有重要作用
我国奶牛养殖当前主要发展地在农村,大部分的奶牛由农民饲养.
风险评估对象
引进动物,动物产品,动物遗传物质
饲料,特别是动物源性饲料
生物制品和动物病理材料存在危害因素的.
根据需要,对输出地的动物卫生和公共卫生体系进行评估.
风险评估过程
传入评估
评价风险传入的可能性
发生评估
评价引进动物等发生疫病的可能性
后果评估
发生后的危害程度
风险预测
根据上述评估,进行综合分析,获得风险预测结果.
包括
传入评估应当考虑以下因素:
(一)生物学因素
易感因素:
如动物种类,年龄,品种等.
病原因素:
病原流行种类,严重程度等.
对方的管理因素
免疫,检疫,监测,处理,卫生等管理技术,措施,规划…;
传入评估应当考虑以下因素:
(二)对方管理因素
对疫病控制的政策
动物卫生和公共卫生体系要求
危害因素的监控计划和区域化措施
传入评估应当考虑以下因素:
(三)商品因素
如引进数量,减少污染的措施,加工过程的影响,贮藏和运输的影响.
发生评估应当考虑的因素:
(一)生物学因素
如易感动物,病原性质等;
(二)国家因素
如传播媒介,人和动物数量,文化和习俗,地理,气候和环境特征;
(三)商品因素
如进境商品种类,数量和用途,生产加工方式,废弃物的处理.
后果评估应当考虑以下因素:
(一)直接后果
如动物感染,发病和造成的损失,以及对公共卫生的影响等;
(二)间接后果
如危害因素监测和控制费用,补偿费用,潜在的贸易损失,对环境的不利影响.
风险预测
对传入评估,发生评估和后果评估的内容综合分析.
作出风险预测.
第三步
管理
奶牛场传染性生物因子风险
风险了解和风险评估是风险管理的基础
要根据风险评估的结果,确定与奶牛场适当保护水平相一致的风险管理措施.
风险管理是制定计划和采取措施降低损失的可能性,或者是减少实际损失.
制定风险管理措施,要注意有效性和可行性.
风险管理_
管理包括事前,事中和事后三个阶段.
事前控制的目的主要是为了降低损失的概率,
事中和事后控制主要是为了减少实际发生的损失.
风险管理的基本形式
风险回避,风险转移,风险保留
风险回避_
风险回避是主体有意识地放弃风险行为,可以完全避免特定的损失风险.
出现以下情况,可以采用这种方法:_
(1)主体无能力消除或转移风险,出现风险无能力承担该
或_得不到足够的补偿.
(2)存在可实现同样目标的其他方案.
风险转移
是指通过契约,将风险部分或全部转移给受让人承担的行为.
风险转移的主要形式是契约和保险.
(1)契约转移.
通过签订合同,可以将部分或全部风险转移给一个或多个其他参与者.如公司加养殖场的模式.
通过参加契约组织,有组织共同承担全部或部分风险.如参加行业协会等.
(2)保险转移.
保险是国外使用最为广泛的风险转移方式._
(3)其它形式转移.
如财政补贴等.
4,风险保留
即风险自负.一般来说,如果损失发生,经济主体应有能力承担,否则应考虑其它方式以减低风险程度.
风险保留包括无计划自留,有计划自我保险.
(1)无计划自留.
指风险损失发生后从收入中支付,即不是在损失前做出资金安排.
一般来说,无资金保留应当谨慎使用,因为如果实际总损失远远大于预计损失,将引起资金周转困难.
(2)有计划自我保险.
指可能的损失发生前,通过做出各种资金安排以确保损失出现后能及时获得资金以补偿损失.
有计划自我保险主要通过建立风险预留基金的方式来实现._
风险管理程序
首先进行可行性评价
制定精细的管理规划
区别先后,考虑难易程度,考虑经济效益,特殊情况.
管理规划实施的反馈
直接挑战,短期目标,长期目标.
持续性解决问题
获取建议
建议非常有赖于经验和知识
风险管理常规内容
严格的隔离措施
牛场范围,围栏,门卫要严格把关
限制动物间的接触
相邻动物,野生动物(包括鸟类),流浪猫,狗
…
有效的动物卫生制度
环境,用具,饲料,人员等卫生规定
为人员,车辆制定生物安全规定
非传染性病,死动物处理.
新生动物卫生管理尤其重要
…
风险管理常规内容
动物标识
具有非常重要的作用:
健康信息,处理要求
在牛场中的位置,档案
每头动物要有健康记录
风险管理常规内容
犊牛要在出生后6小时内摄取足够的初乳
防止与大牛和污染环境接触
员工培训
发现和报告患病动物
每天检查动物健康状况
及时清理器械,用具,服装
立即隔离病畜
隔绝空气流通, 避免与其它动物接触
风险管理重点
传染源管理
传播途径管理
易感动物管理
易感动物管理
新进动物检疫,免疫
包括新购买的,重新回归的要隔离检疫.
根据评估选择使用疫苗免疫.
兽医根据实际情况作出隔离,检疫,免疫方案,尤其要注意重大疫病.
注意预防和检疫用疫苗,试剂的有效性
使用者要经过有关的培训
易感动物管理
要制定免疫预防规划
制定年度或半年性规划
规划要针对实际情况
对非正常现象及时调查
神经症状, 猝死, 暴死…
迅速和恰当地处理病畜
淘汰和无害化处理
检验以了解病因
传染源管理
确定要避免哪些传染源进入奶牛场
重大动物疫病,重要人畜共患病等
认真实施风险评估,以达到避免引进不可接受传染源的危险
传播途径管理
需要了解所有的传播途径
了解不同感染途径= 获得控制
以便为家畜养殖制定出使疫病风险降低到尽可能小的程度
针对经过评估的传染性因子
确认风险范围,对象…
设计好管理方案,以使得感染的可能性最小化.
传播途径
传染因子的扩散
动物 到 动物
动物 到 人
各种传播途径
气溶胶
直接接触
污染物
消化道
媒介传播
人畜共患
气溶胶传播
传染因子附着在雾滴上
通过空气传播
气溶胶一般情况下不稳定
只能近距离传播
有效传播距离内有易感动物
直接接触传播
环境中存在传染因子
开放的疮口, 粘膜,皮肤
血液,唾液, 面对面, 磨蹭,撕咬
传染因子的复制
饲养
母兽和子代
污染物传播
污染非生命物质
刷子,针
携带传染因子到易感动物
交易
交通工具
人类
消化道
消化道传染
饲料, 水
粪便,尿,唾液
其它污染
(反刍物)
舔/咀嚼
污染
环境
媒介传染
昆虫
从病畜获得病原
传染给其它动物
跳蚤, 扁虱, 蚊子
苍蝇, 蟑螂
环境污染
环境中病原
土壤中存活的病原, 器官组织
动物和人可从以下途径感染环境中病原
吸入
直接接触
污染物
口入
媒介
谢谢
In this overview presentation, we will introduce the concept of biological risk management (BRM) and discuss how it applies to beef and dairy producers.
Biological risk management is the overall process of awareness education regarding the risk of infectious diseases entering or spreading through an animal facility. It also involves evaluating and managing those risks. BRM is designed to help livestock producers understand the need for disease control, not only for foreign animal disease threats but domestic diseases as well. Biological risk management provides the tools to minimize the risk (photo courtesy of: DB Weddle).
Risk means different things to different people. It is imperative to first identify what those involved with the operation think about the real and potential risks of infectious and zoonotic diseases. The public often relies heavily on previous experience, the media, and their environment. What risks are deemed acceptable or tolerable also varies between individuals. The inset photo demonstrates the attention directed toward the first US case of BSE in 2003 (source CNN).
Risk means different things to different people. It is imperative to first identify what those involved with the operation think about the real and potential risks of infectious and zoonotic diseases. The public often relies heavily on previous experience, the media, and their environment. What risks are deemed acceptable or tolerable also varies between individuals. The inset photo demonstrates the attention directed toward the first US case of BSE in 2003 (source CNN).
This is also the period where one may encounter many of the obstacles and challenges to educating about risk management. Common negative beliefs include: "I already know this stuff", "We have always done it this way", "I''ve already had most everything on this farm", "I don''t have enough time to mess with this", "It''s too expensive", and "Our animals were tested once and we found nothing, it was just a waste of money".
While it is difficult to prove and measure the benefit of things that don''t happen, counter-arguments tend to fall into three categories: there is a risk, it is economically worthwhile to prepare, and the overall impact must be considered. Some beliefs that may require a change of mindset include: "Infectious/zoonotic disease outbreaks can and do happen", "Prevention is less costly than treatment", "Protecting your financial investment and your future assets from liability is worthwhile insurance" and of increasing importance is the "Prevention of disease through awareness and management".
BRM recognizes that diseases cannot be eliminated, but that the risk can be managed through effective control measures. As animal caretakers, it is our duty to be knowledgeable of the animal and its environment to minimize the risk of disease._For_nearly all_diseases there is a relationship between dose exposure and severity of disease._For diseases that are always present (endemic), reducing the dose of infectious agent the animal is exposed to can positively affect the farm''s economic impact and help justify the cost of implementing BRM. Many different solutions exist and because all cattle facilities are different, there is not a one-size-fits-all answer. Photo depicts cattle in a pasture and the owner walking through them monitoring for illness (courtesy of USDA, taken by Bill Tarpenning).
Livestock producers have a lot of contact on a daily basis with animals. In most cases associated with infectious diseases, the farmer has been previously exposed and has developed some type of immunity to it. This is not the case with foreign animal diseases or if their health becomes compromised because normal diseases could make them ill. This immunocompromised population is more vulnerable to zoonotic diseases, those that are spread from animals to humans. Immunocompromised individuals include the elderly, children under the age of 5, pregnant women, chemotherapy patients, organ transplant recipients, persons with HIV/AIDS, and people with chronic diseases such as diabetes. This makes disease awareness imperative. The top photo shows an elderly farmer, while the bottom photo shows another susceptible population, an immunocompromised person in a nursing home (photo sources USDA).
Let us begin our discussion by addressing the importance of biological risk management.
Let us begin our discussion by addressing the importance of biological risk management.
Let us begin our discussion by addressing the importance of biological risk management.
Once a facility or operation has been evaluated, the challenges to implementing a successful BRM plan can be identified. Only then can a tailored management plan be proposed and implemented. When first working on change, prioritize those items that are relatively easy to implement, inexpensive, yet yield rewards. There is no common formula for what that entails, and rewards will be different for everyone. Simply reducing exposure could be beneficial. The photo shows a large feedlot in Texas (photo source DB Weddle).
There are many general prevention steps that every farm could implement that would help prevent against a variety of diseases that are transmitted in various ways. Things such as knowing what is in the area of your farm perimeter- farms, neighboring livestock, wildlife; individual animal identification, animal health protocols, recognizing and dealing with sick and dead animals, isolation/quarantine, supply handling, and neonatal management. This next section will provide some general prevention recommendations for those areas. Note to presenter: This next section will review general prevention practices; this is where you could hand out the General Prevention Practices document and Checklist to the audience and have them follow along. The checklist can be taken home so they can evaluate their own operation.
If more than one person works on an operation, individual animal identification is imperative for proper communication of health status, treatment needs, antibiotic withdrawal/residue prevention status, and location on farm. Individual animal identification is imperative to proper record keeping (vaccinations, treatments, pregnancy status) which is an integral part of managing animals and minimizing disease risk on farm. Keeping treatment records is an integral part of minimizing disease risk on farm because protocols can be tracked over time with your veterinarian and used to determine whether things are working in various disease situations. If these black Angus heifers did not have identification tags in their ears, it would be hard to communicate health status to someone else because they all look alike (photo source: DB Weddle, ISU).
Adequate ingestion of colostrum is the most important consideration for calf''s resistance to disease and all calves should receive colostrum within 6 hours of birth. A calf''s immune system depends on the antibodies in colostrum. After 6 hours of life, the calf''s ability to absorb antibodies from colostrum diminishes. Once a calf is born, subsequent milk production in the cow will dilute colostrum and therefore require the calf to consume more for maximum antibody absorption and immune function. Another good practice is to prevent contact of the neonate with older animals and also contaminated environments. This will decrease the pathogen load to the newborn and give the colostrum the ability to provide protection. The photo depicts colostrum in a freezer that is stored in palpation sleeves (with the fingers tied off), labeled with the cow ID number and dated. This allows for easy thawing and making sure the calf gets colostrum from one cow (photo courtesy of DB Weddle).
Cattle that are identified as ill should be removed from the rest of the herd immediately and placed in an isolation area where ventilation, feed/water, and other equipment are not shared and direct contact with other animals does not occur in order to minimize the risk of disease spread. Newly introduced animals, including show cattle/calves that have been away from the farm, may be carrying diseases that your home herd is not immune to, so quarantine them for a period of time. Time spent in isolation and quarantine varies depending on the risk so this should be determined together with your herd veterinarian. Before taking animals out of isolation or quarantine, it is a good risk management plan to test them for key diseases (determined together with your herd veterinarian) and make sure they are not carrying diseases that could be introduced into the home herd.
To monitor health status, it is imperative to keep health records on every animal. There are many computer programs out there that can simplify this for producers as the photo depicts (courtesy of Dale Moore, UC Davis VMTRC). It is important to work with your clients to review treatment and vaccination records so alterations can be made to the animal health protocols on farm; this will also help ensure what you think is happening is actually happening. Producers should work with their veterinarian to investigate those animals that present with unusual symptoms or are unresponsive to treatment, especially neurologic cases, downers and those that die suddenly.
To monitor health status, it is imperative to keep health records on every animal. There are many computer programs out there that can simplify this for producers as the photo depicts (courtesy of Dale Moore, UC Davis VMTRC). It is important to work with your clients to review treatment and vaccination records so alterations can be made to the animal health protocols on farm; this will also help ensure what you think is happening is actually happening. Producers should work with their veterinarian to investigate those animals that present with unusual symptoms or are unresponsive to treatment, especially neurologic cases, downers and those that die suddenly.
The approach that was taken in the development of these biological risk management tools was to look at diseases based on their route of transmission to the animal, or human in the case of zoonotic diseases. An advantage of minimizing risk by examining routes of transmission is that it will also help protect against new or unanticipated infectious diseases. While disease agents and the infections they produce vary, they all have one thing in common: the animal must be exposed to them to develop disease. Once it is understood that different diseases can be acquired orally and others are breathed in via aerosol transmission, it is easier to gain control over them. This classification system is effective and easy to understand without requiring knowledge about a wide range of diseases. From a management standpoint, it may be easier to identify risk areas, such as fomites, and then design protocols to minimize exposure.
Disease agents can be spread from animal to animal, or animal to human, through a variety of transmission routes. For the purposes of the biological risk management materials, 5 main routes were identified: aerosol, direct contact, fomite, oral and rector-borne. The sixth route, zoonotic, can be spread from animals to humans through one of the 5 previously listed routes. Many infectious agents can be transmitted by more than one route of infection. This photo shows several dairy cows grazing in a pasture (photo source USDA – ARS). Note to presenter: This next section will review each route of transmission; this is where you could hand out the Transmission Route Definitions handout to the audience and have them follow along.
Aerosol transmission occurs when disease agents contained in droplets are passed through the air from one animal to another, or animal to human. Most pathogenic agents do not survive for extended periods of time within the aerosol droplets, and as a result, close proximity of infected and susceptible animals is required for disease transmission. Top photo depicts a tunnel ventilated dairy building; aerosol transmission is of concern if not properly ventilated (photo source DB Weddle). The bottom photo shows a situation where cattle are always in close proximity to one another- a feedlot (photo source USDA).
Transmission by direct contact requires the presence of an agent or organism in the environment or within an infected animal. A susceptible animal becomes exposed when the agent directly touches open wounds, mucous membranes, or the skin through blood, saliva, nose to nose contact, rubbing or biting. It is important to note that depending on the disease agent, it is possible for direct contact transmission to occur between animals of different species as well as to humans. For the purposes of the BRM information, reproductive transmission will encompass those diseases spread through venereal and in-utero routes. Venereal transmission (breeding), a type of direct contact, is the spread of pathogenic agents from animal to animal through breeding. In-utero (dam to offspring) transmission, another type of direct contact, is the spread of pathogenic agents from dam to offspring during gestation. The top photo shows a group of calves together in a pen with ample opportunities for direct contact transmission (photo source DB Weddle, ISU). The bottom photo shows a young heifer licking her newborn calf (photo source USDA).
A fomite is an inanimate object that can carry disease agents from one susceptible animal to another. Examples of fomites include contaminated brushes, clippers, needles, balling guns (middle picture; photo source DB Weddle) clothing, milking units, teat dip cups, feed or water buckets, and shovels. The top photo depicts a situation in which disease transmission may occur via a fomite, grooming equipment (photo source USDA). Traffic transmission is another special type of fomite transmission in which a vehicle, trailer, or human spreads organic material to another location. The bottom photos show the entrance to a dairy with a sign stating the premise''s visitor restrictions, as well as a handy place for boot distribution and collection at the entrance to the farm (photos source DB Weddle).
Pathogenic agents can also be transmitted to animals or humans orally through consumption of contaminated feed, water or licking/chewing on contaminated environmental objects. Feed and water contaminated with feces, urine or saliva are frequently the cause of oral transmission of disease agents. However, feed and water can be contaminated with other infectious agents as well such as ruminant protein in ruminant feed. The top photo depicts a Holstein and an Ayrshire drinking from different sides of a water tank- if it becomes contaminated, all of the animals in those pens could be exposed (photo courtesy of DB Weddle, ISU). The bottom depicts Hereford calves eating silage at a wooden feed bunk, a potential source of bird, rodent, or dog contamination (photo source USDA).
Vector-borne transmission occurs when an insect acquires a pathogen from one animal and transmits it to another. Fleas, ticks, and mosquitoes are common biological vectors of disease, and flies and cockroaches are a common mechanical vector. The top photo shows a calf with two old insecticide ear tags and numerous face flies, while the bottom photo shows an adult deer tick, Ixodes scapularis capable of spreading Lyme disease (photo source USDA).
Many disease agents can survive for extended periods of time in soil or other organic material like bedding, old feed, etc. Animals or humans can then acquire the disease agent from the environment through inhalation or aerosolization, oral consumption, direct contact, or via fomites as discussed in previous slides. Therefore, environmental contamination should not be ignored but recognize the routes it uses to get into the animal can be controlled. This photo demonstrates the wide realm of environmental contamination possibilities (photo source DB Weddle).
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