猪场重要虫媒及其传播病原研究进展

近年来,非洲猪瘟、牛结节性皮肤病等外来可由虫媒传播的疫病肆虐中国,而一些已在国外流行的虫媒传播病原如非洲马瘟等传入中国的风险也越来越高,严重危害中国畜牧养殖业的发展和公共卫生安全。特别是2018年8月以来非洲猪瘟在中国的流行给养猪业带来重要警示信息,即防止猪场媒介生物进入并阻断其携带病原的传播将成为猪场生物安全的重点。蚊、蝇、蠓及蜱等是猪场和发病猪群传播疫病的重要虫媒因素,虫媒种类及从虫媒中分离到的病毒、细菌、寄生虫等病原种类繁杂,虫媒生物特性的差异对病原的传播方式和传播能力也不尽相同。鉴于此,作者详细归纳了猪场存在的主要虫媒种类及其传播的重要猪病病原,包括猪乙型脑炎病毒、猪繁殖与呼吸综合征病毒、非洲猪瘟病毒、盖塔病毒、猪肠道冠状病毒、大肠杆菌、猪链球菌等,并探讨其危害性和传播风险,以降低猪场虫媒传播疾病所带来的经济损失。     

Virus survival in slurry: analysis of the stability of foot-and-mouth disease, classical swine fever, bovine viral diarrhoea and swine influenza viruses

Farm slurry can be highly contaminated with viral pathogens. The survival of these pathogens within slurry is important since this material is often distributed onto farm land either directly or after heat treatment. There is clearly some risk of spreading pathogens in the early stages of an outbreak of disease before it has been recognized. The survival of foot-and-mouth disease virus, classical swine fever virus, bovine viral diarrhoea virus and swine influenza virus, which belong to three different RNA virus families plus porcine parvovirus (a DNA virus) was examined under controlled conditions. For each RNA virus, the virus survival in farm slurry under anaerobic conditions was short (generally ≤ 1 h) when heated (to 55°C) but each of these viruses could retain infectivity at cool temperatures (5°C) for many weeks. The porcine parvovirus survived considerably longer than each of the RNA viruses under all conditions tested. The implications for disease spread are discussed.     

猪支原体肺炎净化研究进展

猪支原体肺炎是由猪肺炎支原体引起的一种严重危害养猪业生产的传染病,该病传播迅速,且一旦侵入就难以清除,控制和净化该病已成为世界养猪生产所面临的挑战。世界各国都采取了各种不同的措施净化此病,也取得了一定的成效。本文列举了美国,欧洲各国及中国猪支原体肺炎净化成功例子及经验,并加以总结归纳,为国内猪支原体肺炎的净化提供参考。     

Risk for interspecies transmission of zoonotic pathogens during poultry processing and pork production in Peru: A qualitative study

Interspecies transmission of pathogens is an unfrequent but naturally occurring event and human activities may favour opportunities not previously reported. Reassortment of zoonotic pathogens like influenza A virus can result from these activities. Recently, swine and birds have played a central role as “mixing vessels” for epidemic and pandemic events related to strains like H1N1 and H5N1. Unsafe practices in poultry markets and swine farms can lead to interspecies transmission, favouring the emergence of novel strains. Thus, understanding practices that lead to interspecies interactions is crucial. This qualitative study aimed to evaluate poultry processing practices in formal and informal markets and the use of leftovers by swine farmers in three Peruvian cities: Lima (capital), Tumbes (coastal) and Tarapoto (jungle). We conducted 80 direct observations at formal and informal markets and interviewed 15 swine farmers. Processors slaughter and pluck chickens and vendors and/or processors eviscerate chickens. Food safety and hygiene practices were suboptimal or absent, although some heterogeneity was observed between cities and chicken vendors versus processors. Both vendors (76%) and processors (100%) sold the chicken viscera leftovers to swine farmers, representing the main source of chicken viscera for swine farms (53%). Swine farmers fed the chicken viscera to their swine. Chicken viscera cooking times varied widely and were insufficient in some cases. Non‐abattoired poultry leads to the sale of poultry leftovers to small‐scale swine farms, resulting in indirect but frequent interspecies contacts that can lead to interspecies transmission of bacterial pathogens or the reassortment of influenza A viruses. These interactions are exacerbated by suboptimal safety and hygiene conditions. People involved in these activities constitute an at‐risk population who could play a central role in preventing the transmission of pathogens between species. Educational interventions on hygiene and food safety practices will be important for reducing the risk of interspecies influenza transmission.     

The potential risk of infectious disease dissemination via artificial insemination in swine

Artificial insemination (AI) is one of the most widely used assisted reproductive technologies in swine. To maintain a healthy semen trade, it is crucial that diligence be given to managing and minimizing the chance of extended semen playing an epidemiological role in the transmission of infectious disease. In swine, pathogens of primary importance, which may be transmitted through semen include Aujeszky's disease, brucellosis, chlamydophilosis, porcine circovirus type 2, classical swine fever, Japanese encephalitis, leptospirosis, parvovirus, porcine reproductive and respiratory syndrome, rubulavirus, foot-and-mouth disease and swine vesicular disease. This paper will summarise the current state of knowledge pertaining to these pathogens in relation to swine AI.     

我国主要猪病毒病的危害及其综合防控

近年来,我国猪病毒病的疫情越来越复杂,经常会出现几种病毒混合感染的现象,给我国养殖户带来了严重损失。主要从猪病毒病的种类、危害、传播方式、检测以及防控措施等方面着重介绍了对我国养猪业危害最大的5种猪病毒病,即猪口蹄疫、猪水疱病、猪瘟、高致病性猪蓝耳病和猪腹泻病,以期为相关研究提供参考。     

猪冠状病毒的起源与遗传演化

冠状病毒变异率高,宿主广泛,主要感染哺乳动物和禽类,严重威胁公共卫生安全与养殖业发展.生猪养殖业中,冠状病毒也是危害猪只健康的重要病原.本研究对4种代表性猪冠状病毒:猪传染性胃肠炎病毒(transmissible gastroenteritis virus,TGEV)、猪流行性腹泻病毒(porcine epidemic...     

Natural history of influenza in swine in Hawaii: swine influenza virus (Hsw1N1) in herds not infected with lungworms

To obtain more information on mechanisms by which influenza virus is perpetuated in swine, retrospective and prospective seroepizootiologic observations were made in swine herds in Hawaii, beginning in 1974. An epizootic of swine influenza (Hsw1N1) virus was observed in November and December 1976, involving 31 of 41 herds. Features of the epizootic included (1) infection of all herds within one geographic location, during a short period; (2) no obvious introduction of virus from the outside in most herds; (3) epizootics mainly in herds with serologic history of infection; (4) no evidence that lungworms were involved; and (5) little clinical disease associated with infection. There was evidence of viral activity in some herds before the epizootic period and afterward in two of three herds monitored. Evidence of viral transmission by feral animals was not obtained. Data indicated that swine influenza virus persists through latently or chronically infected swine, with epizootics occurring when herd immunity reaches a critically low degree.     

Research Progress on Epidemiology of African Swine Fever

African swine fever (ASF) is mainly occurred in Africa.It invades into Europe and America by chance,then invades in to Eastern Europe and the Caucasus area.And it has not been controlled until now.African swine fever virus (ASFV) can spread by soft tick vectors and affect wild and domestic pigs.The ability of the virus to survive within a particular ecosystem is defined by the ecology of its wild host populations and the characteristics of livestock production systems.African swine fever is viral disease of domestic and wild pigs which leads high mortality and causes great economic losses due to absence of available vaccine and treatment.Apart from prevention and culling,there are no other control measures.Prevention and control of the infection require good understanding of its epidemiology,so that targeted measures can be carried out.     

非洲猪瘟流行病学研究进展

非洲猪瘟(African swine fever,ASF)主要在非洲大陆流行,它通过偶然机会侵入到欧洲和美洲,之后进一步侵袭到了东欧和高加索地区,且到目前也未完全控制。非洲猪瘟病毒(African swine fever virus,ASFV)可通过软蜱传播,感染野猪和家猪,其在特定生态系统中的生存能力由它所在的野生宿主种群和畜牧生产系统来界定。ASF是可导致家猪和野猪死亡率极高的病毒性疾病,且因缺少有效的疫苗和治疗方法而造成巨大的经济损失。除了预防和扑杀,暂无其他更好的应对方法,所以需要很好地了解ASF流行病学,预防和控制其传播,以便实施更多有针对性的措施。     

基于多重PCR的寡核苷酸基因芯片检测猪瘟病毒,猪繁殖与呼吸障碍综合征病毒及猪圆环病毒1型和2型

为了建立一种可同时检测区分猪瘟病毒(CSFV),猪繁殖与呼吸障碍综合征病毒(PRRSV)和猪圆环病毒2型(PCV-2)的寡核苷酸基因芯片方法,本研究针对每种病毒设计了4条～6条寡核苷酸探针,检测低限为1.6×104PCV-2拷贝数/μL,1.6×104CSFV拷贝数/μL,1.6×105PRRSV拷贝数/μL,比琼脂糖凝胶灵敏约10倍。利用建立的寡核苷酸基因芯片方法对76个仔猪样本进行了检测,检出了3种病毒的存在,其中25个样本(32.9%)同时感染了2种以上病毒。结果表明寡核苷酸基因芯片检测是一种快速、灵敏和高效的猪只混合感染病毒的病原学诊断方法。     

Prospects for the use of embryos in the control of disease and the transport of genotypes

Transfer and low temperature storage of embryos are now proven techniques for a number of mammalian species. These techniques are useful in control of disease and in saving genotypes from infected animals. The place of embryos in the epidemiology of disease depends upon whether the causative organism can gain entry to the oocyte before or at fertilisation and on whether the young embryo can be invaded by organisms in the uterine environment. There is little evidence that important live-stock diseases are transmitted via gametes. The zona pellucida surrounding the embryo is an effective barrier against a number of important disease organisms; in some cases the embryo is susceptible once it has hatched from the zona pellucida. It is important therefore in considering the use of embryos in disease control, to ensure that virus is not attached to the surface of the zona pellucida from where it can infect the recipient and/or the embryo after hatching. Washing procedures have been devised together with the use of enzymes and antisera to remove virus from the surface of embryos. Some viruses enter pores and sperm tracks in the zona and removal of these may present a problem. African swine fever virus has been shown to resist removal by treatment with enzymes. There are no guidelines as to the likely interaction between a certain virus and embryos. Therefore each virus of interest must be tested to determine whether it can be transmitted via washed embryos. Nevertheless there are numerous instances of the use of embryo transfer to eradicate a specific disease or to save valuable genetic material from infected animals without transmitting disease.     

牛病毒性腹泻病毒侵染细胞机制的研究进展

牛病毒性腹泻病毒(BVDV)是反刍动物和猪体内广泛存在的危害动物健康的重要病原体.BVDV感染牛后主要引起牛的持续性感染、免疫耐受、免疫抑制、繁殖障碍及急慢性黏膜病等临床症状,给养牛业造成重大的损失.其致病机理非常复杂,给该病的治疗和根除带来极大的困难.随着分子病毒学研究的发展以及对猪瘟病毒和黄病毒科其他成员的研究,人们在BVDV分子水平和细胞水平的研究方面也取得了一些进展.就此,作者从BVDV入侵细胞、在细胞内的复制以及与宿主蛋白分子相互作用等方面进行综述,有助于阐明BVDV致病和在体内持续存活的机制,为该病的防治和疫苗研发提供新的思路和对策.     

Swine diseases transmissible with artificial insemination

The transport of fresh and frozen semen to be used for artificial insemination creates a mode of disease transmission between farms. Normally, semen contains a number of nonpathogenic bacterial contaminants; however, excessive bacterial contamination can result in infertile matings. Contamination with a known pathogen, eg, Brucella suis, could initiate a serious outbreak of disease in a recipient herd. Methods to minimize bacterial contamination of semen include sanitary collecting and processing of semen, isolation of boards from certain pathogens, and the addition of appropriate broad spectrum or combination antibiotics to the semen. Mycoplasmas also have been isolated from semen, although transmission by this route is unlikely. The addition of an appropriate antimycoplasmal antibiotic to semen may be warranted in some situations. Numerous viruses have been detected in semen. Their exclusion from semen is especially critical because of their ability to survive in frozen semen. These viruses include pseudorabies virus, porcine parvovirus, enterovirus, adenovirus, vesicular disease virus, and African swine fever virus. The likelihood of disease transmission is greater with the introduction of a boar into a herd than through the use of fresh or frozen semen. We believe that artificial insemination allows for the introduction of new genetics into a breeding program, with minimal risk of disease transmission.     

野猪病原体混合感染的PCR诊断与防控

野猪集约饲养是目前新发展起来的养殖产业之一,野猪抗病力强,发生猪瘟、猪繁殖与呼吸综合征等烈性传染病病例的报道较少。2009年8月,山西寿阳某野猪场出现高发病、高死亡病例,应用PCR技术进行了病原检测,结果为野仔猪混合感染猪肺炎支原体、猪繁殖与呼吸综合征、猪瘟。证明野猪对以上疫病具有易感性,并提出一些防制办法,对野猪饲养建立合理的免疫程序具有一定的参考价值。     

Observations on a Swine Herd Health Program

Observations on a swine herd health program are reported. A primary purpose was to show that such programs could provide economic benefits to swine breeders and sources for breeding stock of minimum disease status. The possible influence of diseases of swine, including atrophic rhinitis and virus pneumonia, on both aspects are discussed. The inadequacy of knowledge of diseases of swine, both specifically and generally, is pointed out. Veterinary supervision of a swine herd will result in economic benefits to an average capable owner. There is both merit and need for such programs, but as to what health standards would be reasonable, practical, and meaningful, is still not clearly defined.     

Analysis of the quality of protection induced by a porcine influenza A vaccine to challenge with an H3N2 virus

Antigenic drift of swine influenza A (H3N2) viruses away from the human A/Port Chalmers/1/73 (H3N2) strain, used in current commercial swine influenza vaccines, has been demonstrated in The Netherlands and Belgium. Therefore, replacement of this human strain by a more recent swine H3N2 isolate has to be considered. In this study, the efficacy of a current commercial swine influenza vaccine to protect pigs against a recent Dutch field strain (A/Sw/Oedenrode/96) was assessed. To evaluate the level of protection induced by the vaccine it was compared with the optimal protection induced by a previous homologous infection. Development of fever, virus excretion, and viral transmission to unchallenged group mates were determined to evaluate protection. The vaccine appeared efficacious in the experiment because it was able to prevent fever and virus transmission to the unchallenged group mates. Nevertheless, the protection conferred by the vaccine was sub-optimal because vaccinated pigs excreted influenza virus for a short period of time after challenge, whereas naturally immune pigs appeared completely protected. The immune response was monitored, to investigate why the vaccine conferred a sub-optimal protection. The haemagglutination inhibiting and virus neutralising antibody responses in sera, the nucleoprotein-specific IgM, IgG, and IgA antibody responses in sera and nasal secretions and the influenza-specific lymphoproliferation responses in the blood were studied. Vaccinated pigs developed the same or higher serum haemagglutination inhibiting, virus neutralising, and nucleoprotein-specific IgG antibody titres as infected pigs but lower nasal IgA titres and lymphoproliferation responses. The lower mucosal and cell-mediated immune responses may explain why protection after vaccination was sub-optimal.     

Transmission of agents of the porcine respiratory disease complex (PRDC) between swine herds: a review. Part 2--Pathogen transmission via semen, air and living/nonliving vectors

The transmission of PRDC-pathogens (PRRSV, influenza virus A, PCV2, M. hyopneumoniae, A. pleuropneumoniae) between swine herds, which was summarized in the first part of the review, mainly occurs via pig movement. The risk of pathogen transmission by insemination with contaminated semen plays only a relevant role in the infection with PRRSV and PCV2. A risk of the aerogen transmission of pathogens between herds within a distance of 2 to 3 km is described for M. hyopneumoniae and PRRSV. Evidence for the other pathogens is not investigated. The PRDC-pathogens are frequently detected in wild boar populations. Therefore, the transmission between wild boars and domestic pigs seems possible by close contacts. PRRSV and M. hyopneumoniae can be transmitted by contaminated clothes and boots, but the use of sanitation protocols appears to limit their spread. Live vectors like rodents or birds seemed to have no special importance for the transmission of PRDC-pathogens.     

猪水疱性口炎病毒基因及其疫苗的研究进展

猪水疱性口炎是由水疱性口炎病毒引起的高度接触传染性的病毒性疾病。其临床特征为猪的唇部,鼻及口腔等处发生水疱,并从口中不断向外流涎,有时常常还发生在蹄冠和趾间皮肤上,其症状主要以水疱为主。该病在全球许多地区造成广泛流行。近年来,由于产品贸易量的增加,猪水疱性口炎病毒也陆续的传入我国。由于该病与猪水疱病、猪口蹄疫和猪水疱性疹等病毒性疾病容易混淆,因此对该病做出准确地诊断与防制显得尤为重要。在VSV疫苗的研究方面,主要是灭活疫苗和弱毒疫苗的研究,而在新型疫苗的研究方面很少。本文主要综述了猪水疱性口炎病毒的基因及其疫苗的研究进展,为进一步了解和预防该病提供参考依据。     

The role of wildlife in transboundary animal diseases

This paper identifies some of the more important diseases at the wildlife-livestock interface and the role wildlife plays in disease transmission. Domestic livestock, wildlife and humans share many similar pathogens. Pathogens of wild or domestic animal origin that can cause infections in humans are known as zoonotic organisms and the converse are termed as anthroponotic organisms. Seventy-seven percent of livestock pathogens and 91% of domestic carnivore pathogens are known to infect multiple hosts, including wildlife. Understanding this group of pathogens is critical to public health safety, because they infect a wide range of hosts and are most likely to emerge as novel causes of infection in humans and domestic animals. Diseases at the wildlife-livestock interface, particularly those that are zoonotic, must be an area of focus for public health programs and surveillance for emerging infectious diseases. Additionally, understanding wildlife and their role is a vital part of understanding the epidemiology and ecology of diseases. To do this, a multi-faceted approach combining capacity building and training, wildlife disease surveillance, wildlife-livestock interface and disease ecology studies, data and information sharing and outbreak investigation are needed.