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猪场饮用水生物安全(二)- AASV 2020

来源:猪译馆 2020-05-21 15:36:38| 查看:

 

译者的话<<

 

病毒性疾病,如禽流感、口蹄疫、蓝耳猪流行性腹泻和非洲猪瘟,在畜牧业中仍然是一个重大问题,并已被证明对包括饮用水消毒在内的众多缓解策略有非常强的抗性。一个消毒程序,如果没有一个能指定具体设备和持续验证其性能的方法,则达不到其本身消毒目的。在这种情况下就会出现一种最糟糕的情形,那就是打着生物安全的旗号进行所谓的无用的消毒

这已成为公认的传播疾病的途径之一,并一如既往地在整个农业行业中被忽视、低估和无视。这一问题对于禽流感、蓝耳猪流行性腹泻如何能够续感染如此长的时间可能至少是一个潜在因素(如果不是代表性原因的话)。

 

猪场饮用水生物安全(二)- AASV 2020

 

Groundwater Biosecurity for Livestock Production and Husbandry (Part 2) – AASV 2020

接上文......

水力学和易感区域

Hydraulics and sensitive geographies<<

 

动物养殖场与邻近的家庭和农场相比,它们耗水量很大,这是值得注意的一个问题。由于这些养殖场从蓄水层中汲取了大量的水(与其他井相比)所在位置的静态水位就降低了。因此,供应其井水系统的地下水将从较远的地方抽取,并通过(和/或围绕)许多不同的土壤和地质结构运输。水流通道在水平或垂直面上都不均匀。

One factor of note for livestock facilities is related to the volume of water they use in comparison to neighboring homes and farms. As larger volumes of water are extracted from the aquifer at such a facility (vs. other wells) the static water level is reduced at the farm’s location. Accordingly, groundwater supplying their well system is pulled from greater distances and transported through and/or around numerous soils and geologic structure(s). Flow pathways are not uniform on either horizontal or vertical planes. 

大量的水是从多孔的区域抽取的,并且重力作用将导致更大量的水从高海拔的更接近易受地表水(病原体)入侵地区的蓄水层流向低的地方。这些因素都会导致为养殖场提供饮用水的供水系统内微生物污染可能性增加。

Greater volumes will be pulled through more porous areas and gravitational force will cause greater amounts of water to flow from higher elevations of an aquifer that are closer in proximity to areas susceptible to surface water (pathogen) intrusion. These factors serve to increase the potential of microbial contamination of well systems proving drinking water for such facilities. 

要理解影响微生物进入地下水,并在地下水中生存和转移的机制的因素。这些微生物会讯速地、广泛地、无规律地、多方向地(垂直/对角线/水平)分布开来,导致在分水岭地区有大量的病毒汇集。这种分布情况也会在发生以下事件中的一件或多件时出现:a)随季节变化而产生的水压变化(:冬季、春季径流)b)气候事件(即:降雨/干旱)c)农作物灌溉地区。d)局部地理海拔变化,e)蓄水层流入/排出的容量、数量和地理位置与(局部)水压变化的关系,f)与病原体来源的距离(即:污水净化系统、污水处理设施、养殖场、粪肥、垃圾填埋场、湖泊/溪流等,g)未固结、多孔、断裂或洞穴状地质的地方,h)封闭区域的均匀性、连续性、多样性和孔隙度(天然的和人工的)i)地下水流动的主要方向、速度和深度。

Understanding the mechanisms influencing entry, survival, transport and concentration of virus in groundwater it is accepted their distribution can be very rapid, broad, irregular and multidirectional (vertical/diagonal/horizontal) with higher viral inputs in areas of watersheds and/or events, that can be described as one, or a combination of the following: A.) Changes in hydraulic pressure in response to calendar season (i.e.: Winter, Spring runoff ), B.) Climatic events (i.e.: rainfall/drought), C.) Areas of crop irrigation, D.) Change in elevation of (inflows) of localized geography(s), E.) Capacity, number and geographic locations of aquifer recharge/discharge in relation to changing (localized) hydraulic pressures, F.) Proximity to pathogen source(s) (i.e.: septic systems, wastewater treatment plants, feed lots, manure, landfills, lakes/ streams, etc., G.) Locations of unconsolidated, porous, fractured or cavernous geologies, H.) Uniformity, continuity, multiplicity and porosity (natural & manmade) of confining horizons, I.) Prevalent direction, speed and depths of groundwater flowage. 

病毒在蓄水层中的存活、积累和释放

Survival, accumulation and release of virus within aquifers<<

众所周知,温度、来自阳光的保护、有机化合物的存在、与微粒的联系以及微生物活动的减少37-39都会影响地下水中病毒的生存能力,物种形成(病毒)和土壤组成也会影响病毒的存活。粘土颗粒在保护病毒免受自然衰变方面特别有效40,41。据报道,某些类型的有机物(例如蛋白质)能很好地保护病毒不被灭活。

As it is known temperature, protection from sunlight, presence of organic compounds, association with particulates and least attenuated microbial activity37-39 influence survivability of virus in groundwater, speciation (virus) and soil composition do so as well. Clay particles are particularly effective at protecting virus from natural decay.40,41  Some types of organic matter (i.e., proteins) are also reported to better protect viruses from inactivation.42 

更值得注意的是病毒通过吸附作用而在地质层中积累的方式。随着时间的推移,这些地方的病毒高度集中。然后被解吸进入蓄水层中的水里,从而形成高浓度的垂直病毒汇集区39,42由于病毒-土壤相互作用对表面电荷非常敏感,任何足以引起电荷逆转的水质变化都会导致病毒的解吸43,44水质变化会导致pH值的升高、离子强度的降低和有机物的存在40,45-47例如,当碱性的污水渗液与地下水混合时,增加的pH值可使病毒迅速解吸和传播,特别是在饱和流条件下48暴风雨后的降雨补给可能会降低离子强度,导致病毒解吸和传播。因此,病毒在进入蓄水层后很长一段时间内仍可能以高浓度周期性地污染蓄水层40,49

Of particular interest is the manner which virus accumulate within geologic strata by adsorption. Over time, virus in such areas become highly concentrated. Then subsequently desorbed unilaterally into the flowage of an aquifer, inherently creating highly concentrated plumbs of virus.39,42 Since virus-soil interactions are very sensitive to surface charge, any water quality change that is enough to cause a charge reversal will result in the desorption of virus.43,44 Water quality changes that can result in desorption include an increase in pH, a decrease in ionic strength, and the presence of organic matter.40,45-47  For example, when alkaline septic effluent mixes with groundwater, the increased pH allows rapid desorption and transport of virus, especially under saturated flow conditions.48  Rainfall recharge after a storm may decrease ionic strength and cause virus to desorb and transported. As such, viruses may continue to contaminate an aquifer at high concentrations on a periodic basis long after their initial entry.40,49 

由于猪流行性腹泻(PEDV)和猪繁殖与呼吸综合征(PRRSV)爆发的季节性特征,很明显水温可能是影响这些病毒生存的关键因素。

Due to the seasonality of porcine epidemic diarrhea (PEDV) and porcine reproductive and respiratory syndrome (PRRSV) outbreaks, it is apparent water temperature may serve as a critical factor regarding their survivability. 

在对南非饮用水中腺病毒的一项为期一年的调查中,发现腺病毒的检测率在7月达到高峰(南非冬季),经处理和未经处理的水样的腺病毒呈阳率分别为30%60%。只有当水温低于23°C时,才能在南非豪登省的Florida西南部的一个河口处检测到肠病毒。在一项体外研究中,在22°C的海水中与在30°C的海水中相比,脊髓灰质炎病毒的存活率和检出率都有所提高。在人工海水中,用逆转录聚合酶链反应(RT - PCR)22°C的水中至少可检测到病毒长达60天,而30°C的水中只能检测到30天。同样地,在海水中,4°C时需要671天才能灭活海水中90%的脊髓灰质炎病毒和甲肝病毒,而在25°C时只需要25天。在一项用聚合酶链反应(PCR)评估一个多功能河口中人和牛的肠道病毒的研究中,发现,所有病毒类型均与冷水温度相关,如图4.23所示23

In a year-long survey of the occurrence of adenoviruses in drinking water in South Africa, adenovirus detection peaked in July (winter in South Africa), when up to 30% and 60% of treated and raw water samples were positive for adenoviruses, respectively. Enteroviruses were detected from an estuary in southwest Florida only when the water temperature was below 23° C. In an in vitro study, enhanced poliovirus survival and detection were observed at 22° Celsius (C) compared to 30° C in seawater. In artificial seawater, viruses were detected by reverse transcription polymerase chain reaction (RT-PCR) for at least 60 days at 22° C but for only 30 days at 30° C. Similarly, in seawater, it took 671 days to inactivate 90% of poliovirus and hepatitis A virus at 4° C and only 25 days at 25° C. In a study evaluating both human and bovine enteric viruses by polymerase chain reaction (PCR) in a mixed-use estuary, it was found that all virus types were correlated with cool water temperatures as shown in Figure 4.23  

4:在一个多用途河口中通过PCR检测人与牛的肠道病毒,发现病毒与冷水的相关性

Human and bovine enteric viruses by PCR in a mixed-use estuary, correlated with cool water

注:20027月至12月,格鲁吉亚阿尔塔马哈河下游的月平均水温(°C)与人肠病毒、人腺病毒(同时检测到)以及牛肠病毒的样本阳性率(n = 5)4。文献:水生环境中人类和动物的肠道病毒:健康风险、检测和潜在的水质评估工具。作者:Theng-Theng Fong, Erin K. Lipp Microbiol Mol Biol Rev. 2005 Jun; 69(2): 357–371.

Note: Percentage of samples positive for human enteroviruses and human adenoviruses (detected simultaneously), as well as bovine enteroviruses, by month versus the mean monthly water temperature (°C) along the lower Altamaha River, Georgia, between July and December 2002 (n = 5)4.Enteric Viruses of Humans and Animals in Aquatic Environments: Health Risks, Detection, and Potential Water Quality Assessment Tools. Theng-Theng Fong, Erin K. Lipp Microbiol Mol Biol Rev. 2005 Jun; 69(2): 357–371.

病毒在地下水中的浓度

Concentration of virus in groundwater<<

病原体浓度的短期峰值可能大大增加疾病传播的风险。并且,针对微生物的水质检测结果通常不能及时提供,以便管理人员采取行动,防止不安全的水供应进入养殖场50一般来说,地下水中病毒的存在和浓度可以被描述为瞬态、间歇或短暂的,因为井水往往不会连续两个样本都是病毒阳性,而且每个样本的检测频率也很低14,51这可能归因于:a)优先流模式;b)不断减少的水量流经病毒时病毒的浓度;c)吸附-解吸过程。因此,有必要考虑它们向环境中散播的病毒量以及它们到达蓄水层的速度有多快。事实上,城市深井中的病毒浓度通常与湖泊中(湖表水)的病毒浓度一样高,甚至更高21来自受感染的个体(和群体)的粪便中的病毒数量从每克粪便中10万到*1000亿个不等53这个含量也可以代表地下水蓄水层中病毒的潜在浓度。

Short-term peaks in pathogen concentration may increase risk of disease transmission considerably. Furthermore, results of water quality testing for microbes are normally unavailable in time for management to take action and prevent the supply of unsafe water from entering a livestock facility.50  In general, virus occurrence and concentration in groundwater can be characterized as transient, intermittent or ephemeral, because wells are often not virus-positive for two sequential samples and the detection frequency is low on a per sample basis.14,51  his may be attributable to A.) preferential flow patterns; B.) concentration of virus populations within diminishing volumes of water flowing through them; C.) adsorption-desorption processes. Accordingly, it is necessary to consider the extremely high numbers by which they are shed into the environment and how rapidly they may reach an aquifer. In fact, viral concentrations in deep municipal wells are generally as high as, or higher than virus concentrations in lake (surface) water.21  The number of virus from infected individuals (and animals) range from 100,000 up to *100,000,000,000 per gram of stool53  and can be representative of the potential concentration of virus within groundwater aquifers. 

*蓄水层输入浓度势:如果一个病毒代表1英寸,那么1克粪便中病毒数量的直线距离相当于地球周长的63.4倍。

*Interpretation of aquifer input concentration potential: If a virus represented 1 inch, the lineal distance of the number of virus contained within 1 gram of stool would be equivalent to the distance of 63.4 times the circumference the Earth.

现状:家畜行业的饮用水消毒

Current synopsis: disinfection of drinking water within the livestock industry<<

 

病毒性疾病,如禽流感(家禽)、口蹄疫()蓝耳猪流行性腹泻和非洲猪瘟(),在畜牧业中仍然是一个重大问题,并已被证明对包括饮用水消毒在内的众多缓解策略有非常强的抗性。因而,对养猪设施的性能标准(要求的消毒水平)仍然是难以定论的。也正因此,尚未有针对购买水消毒系统所需的性能规范,同时还缺少用于验证所安装的消毒系统是否能真正运行的性能监控系统。一个消毒程序,如果没有一个能指定具体设备和持续验证其性能的方法,则达不到其本身消毒目的。在这种情况下就会出现一种最糟糕的情形,那就是打着生物安全的旗号进行所谓的无用的消毒

Viral illnesses such the Avian Influenzas (Poultry), foot-and-mouth (Cattle) and PRRSV, PEDV & African swine fever (ASF) (Swine) continue to be a significant concern within the livestock industry and have proven to be very resilient to an exhaustive list of mitigation strategies, including disinfection of drinking water. Although, a performance standard (level of disinfection required) for swine facilities remains elusive. Thusly, performance specifications required for the purchase of water disinfection systems remain absent, along with performance monitoring systems required to validate if an installation is, in fact working. A disinfection program, absent of a means to specify equipment and validate its performance on an ongoing basis lends itself to defeating its purpose. In this case, the worst-case scenario would include marketing such a program under the guise of providing a viable measure of biosecurity. 

这已成为公认的传播疾病的途径之一,并一如既往地在整个农业行业中被忽视、低估和无视。这一问题对于禽流感(禽类)PRRSV 与 PEDV()如何能够续感染如此长的时间可能至少是一个潜在因素(如果不是代表性原因的话)。

This has left one of the most recognized means for disease transmission; continue throughout the agricultural industry as being unaddressed, underestimated, and out-of-mind. Possibly, this is representative of, at least one of the underlying factors as to how it is possible for the avian influenzas (poultry) and PRRSV & PEDV (swine), to persist over such a long period of time.

是否有饮用水生物安全的可行模式

Is there a viable model employed for drinking water biosecurity elsewhere?<<

在公共饮用水行业内,对市政供水系统的饮用水必须进行以下消毒:a)灭活或以其他方式清除细菌、病毒和其他可能有害的微生物,这也被称为初级消毒(一级消毒)b)在饮水流经配水系统时,通过杀死潜在的有害微生物来保持水质,并防止生物膜的形成,这被称为二次消毒(二级消毒)

Within the public drinking water industry, disinfection of drinking water serving a municipal water distribution system must include a means to: a.) Inactivate or otherwise remove bacteria, viruses, and other potentially harmful organisms from entering; and is referred to as Primary Disinfection; b.) Maintain water quality by killing potentially harmful organisms and prevent the formation of biofilms as it flows through a drinking water distribution system and is referred to as Secondary Disinfection. 

据信,目前畜牧业中的大多数水消毒设施都是简单地使用化学计量泵将消毒剂直接注入供水系统的总水管中。了解了一级二级消毒的目的后,就知道这种做法只适用于二级消毒,并且不能作为生物安全措施,也不能作为防止病原体进入养殖场饮用水供应的措施。据推测,实现这一目标所需的生物安全水平仍然未知,而迄今为止安装的那些生物安全措施也被认为严重不足,不足以确保养殖场内的饮水不会成为传染病传播的原因。

It is believed most water disinfection installations within the livestock production industry today simply use a chemical metering pump to inject a disinfectant directly into a water main serving a plumbing distribution system. Understanding the purpose of Primary and Secondary disinfection, this practice would lend itself to the latter and serves no relevance as a measure of biosecurity and preventing pathogens from entering a farms’ drinking water supply. Presumably, the level of biosecurity, otherwise required to achieve this objective remains unknown and what has been predominately installed to date would be considered grossly insufficient as a measure to ensure drinking within a livestock facility will not serve as a causal agent for transmission of infectious disease. 

此外,必须理解消毒一词本身并不意味着水源没有病原体。相反,与饮用水有关的消毒,是指通过所使用的技术的敏感性、应用和安装方式以及持续的性能验证来确保供水系统不存在病原体的可能性。鉴于此,在考虑购买各种饮用水消毒系统时,应避免购买那些号称他们的技术可以对水进行消毒,但是却没有技术资质证明(例如:对病毒的灭活/清除率,流速,温度,以及pH值),也没有(用美国标准试验方法的标准)进行现场日常验证此消毒性能的方法的供应商的产品。

Furthermore, it must be understood the term “disinfection” itself does not translate to a water supply as being free of pathogens. Rather, disinfection as it relates to drinking water, refers to the probability a water supply is absent of pathogens based upon delicacy of the technologies employed, the manner they are applied, installed, and a continuing performance verification to ensure that is. Whereas, in the event various drinking water disinfection systems are being considered for purchase, vendors whom suggest their technology disinfects water, and omits qualification (e.g. ? Log10 inactivation/removal virus at ? low rate ? temperature and ? pH) and the means to verify this performance (via ASTM standards) on-site on a daily basis should be avoided. 

在农业行业接受地下水是一种疾病传播的媒介这一事实之前,这种情况将持续下去。届时,如何验证设备的关键性能要求和正在进行的性能验证将被理解和实施。

This situation will continue until the agricultural industry, accepts groundwater as a vehicle for disease transmission. Thereafter, how critically important performance claims for equipment have been validated and ongoing performance verified will be understood and implemented.

消毒系统的设计和性能验证

Disinfection system design and performance validation<<

如今,人们普遍认为,病毒以不同的浓度存在于地下水蓄水层中,其传染性短则持续数天,长则数年。在被发现之前以不同的速度和方向传播,然后(从地下水井系统中)消失。换句话说,为了防止水生病原体进入养殖场,将需要持续进行水质检测。并且,能够实时提供结果的检测方法也变得非常必要。此外,由于假阳性结果的影响,所采用的检测方法必须可靠,各项程序(质量保证/质量控制)也必须严格执行。

Today it is accepted virus are present within groundwater aquifers in varying concentrations, may remain infectious from days to years, travel at various speeds and direction in advance of being detected and then subsequently disappear (from a groundwater well system). In other words, to prevent waterborne pathogens from entering a livestock operation, water tests would need to be performed on a continuous basis. Plus, analytical methods capable of providing results in real-time become a necessity. In addition, due to the implications of a False-Positive result, analytical methods employed must be reliable and procedures (QA/QC) vigorously implemented. 

从另一方面来说,安装一个强健的病原体屏障也可能是一个更经济和实用的防控方法。多年来,公共供水系统(PWS)一直负责安全饮用水的生产和配送。这种消毒系统的技术选择、工程设计和日常运行是众所周知的,并已被证明是有效和可靠的。畜牧业可以考虑使用这种经过试验并被证明可行的模式作为一种切实可行的防控方法。

Alternatively, the installation of a robust pathogen barrier may represent a more economical and practical approach. Public Water Systems (PWS) have been charged with the production and distribution of microbiologically safe drinking water for many years. Technology selection, engineering design and ongoing operation of such disinfection systems are well known and have proven to be effective and reliable. Utilizing such a tried and proven model may serve as a practical approach the livestock industry would consider.

 

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