猪瘟临床病征的一些新知识

虽然人们对猪瘟的认识已有几十年 ,但目前对其的认识仍在深化之中。看来临床诊断仍然是个问题 ,原因主要是由于必须进行范围广泛的鉴别诊断 ;同时 ,一些新的疾病 ,如猪繁殖和呼吸综合征(PRRS)以及猪皮炎和肾病综合征 (PDNS)等的出现 ,而使诊断进一步复杂化 ;另外是还必须在不同病型 (急性、慢性和先天性 )之间正确鉴别。急性型田间病例的感染途径主要是与病猪或污染 (如泔脚 )经口、鼻直接或间接接触。在饲养密集的区域病毒很容易在邻近的猪舍之间传播 ;疾病也可经公猪的精液传播。潜伏期为 7～ 1 0天。在田间 ,当病毒引进后经 2～ 4周…     

African swine fever and classical swine fever: a review of the pathogenesis

This paper describes major pathogenetic mechanisms of African and Classical Swine Fever virus infections. The interactions between both viruses and the monocyte-macrophage-system result in the release of mediator molecules, which are important for the further progression of the diseases. The causes of the thrombocytopenia and the mechanisms of the haemorrhages, which are characteristic in both infections, are described. Apoptotic cell death is regarded as the predominant cause of lymphopenia in both virus infections.     

Transmission of classical swine fever. A review

Classical swine fever (CSF) is one of the most important viral pig diseases. Basic measures to control epidemics of CSF comprise eradication of infected herds and preventive emptying of herds at risk. Identification of these herds at risk is based on knowledge of the different transmission routes of the virus. Direct transmission of CSF is undoubtedly the most efficient way of CSF virus transmission. Data on indirect transmission are variable and often equivocal. Various indirect transmission routes like swill feeding, wild boar and artificial insemination are well described, and the importance is beyond discussion. Mechanical transmission via vehicles and persons are categorized as very important based upon epidemiological research, whereas in experiments they can only be reproduced under worst case conditions. The role of arthropods, birds, rodents, and other animals in the spread of CSF virus remains doubtful. Active transmission by these has never been demonstrated and also very sparse indications for mechanical transmission are available. Also the role of airborne transmission remains debated. However epidemiological as well as experimental data indicate that airborne spread over short distances is probable.     

黑龙江东部地区猪瘟病毒分子流行病学研究

本研究参考公开发表的Alfort株基因组全序列，用计算机软件Dnsstar的PrimerSelect程序设计了两对SCFVE2基因高变区的特异性引物，对黑龙江东部地区分离的5株猪瘟野毒(HL、JN、MSNDD、NSPD)和MSHT株)进行RT-PCR扩增、克隆和序列测定，并将这5株野毒的高变区基因序列与国内外公开发表的参考毒株的相应部分进行了比较。结果表明，5株分离毒均为基因Ⅱ群，且形成两个独立的分支，HL、JN株与HCLV株氨基酸差异在60％以上，而MS株与HQJV株氨基酸差异在30％左右。     

猪瘟的流行现状及防制

近年来 ,猪瘟的发生率呈上升趋势 ,病猪临床表现多样化 ,主要以非典型猪瘟为主。本文根据对四川部分种猪场的流行病学调查及血清学监测情况 ,参照有关资料 ,对当前的猪瘟现状进行分析 ,并提出防制建议。1　流行病学特点1 .1　以零星散发为主 ,常发生在规模化猪场。1 .2　免疫猪群常有发生。且常发生在具有明确免疫程序的规模化猪场。涂长春等报道 [1] ,在发病猪场中 ,接种疫苗 7天内发病的有 8/48个 ,7天后发病的有 2 1 /48个 ,潜伏期一般 2～ 2 1天。1 .3　 1 0日龄内和断奶前后仔猪 (1 5～ 6 0日龄 )发病率较高 ;育肥猪和种猪很少发病。1 …     

猪瘟研究新进展

猪瘟(Hog cholera or Classical Swinefever,CSF)是由猪瘟病毒(Hog cholera virusor Classical Swine fever Virus,CSFV)引起猪的一种高度接触性传染病。其流行广泛,发病率高,死亡率高[1-4]。1984年世界动物卫生组织(OIE)将其列为A类传染病,我国也将此病列为一类动物疫病[4-5]。1历史的回顾 1833年,美国在俄亥俄洲发现CSF[2-4]。1903年,Deschweinitz和Dorset证明CSF的病原体是一种滤过性病毒,而霍乱沙门氏菌只是一种继发感染的细菌,从而最终确定了CSF的病原体。1908年,匈牙利学者HutyraKoves研制出CSF高免血清,证明此时欧洲已有CSF流行。1909年,日本有CSF发生的     

Ability of veterinary pathologists to diagnose classical swine fever from clinical signs and gross pathological findings

Clinical signs recorded in a classical swine fever (CSF)-suspect situation and the results of the subsequent post-mortem examination (PME) from swine submitted to post-mortem during the 1997–1998 CSF epidemic in the Netherlands, were presented in an experiment as anonymous cases (without knowledge of the actual infection status of the submission) to five veterinary pathologists for their judgment: CSF-suspect or non-suspect. It was presented to them in two hypothetical situations: country was free of CSF for 5 years and CSF was detected in the country 2 weeks ago. Subsequently, their judgment was compared to the gold standard (infection status of the submission on the basis of an immunofluoresence assay on tissue samples) and the sensitivity (Se) and specificity (Sp) of clinical diagnosis was estimated. Furthermore, intra- and inter-pathologist agreement on pathological diagnosis was measured. Adding information on clinical signs to information on PME resulted in a significant increase in median Se and a significant decrease in median Sp for a clinical judgment by pathologists. Also, median Se was significantly higher—and Sp significantly lower—for a clinical judgment by pathologists in a situation in which CSF was detected 2 weeks ago in the country compared to the situation in which the country had been free of CSF for 5 years. Apparently, the internal threshold of pathologists is severely adjusted depending on the actual disease situation in a country. Intra-rater agreement ranged from fair to almost perfect for a clinical diagnosis on the basis of PME. There was considerable variation between pathologists, especially if clinical diagnosis was based on the combined information on PME and clinical signs observed in the herd. Inter-rater agreement was substantial for the diagnosis based on information on PME. Inter-rater agreement was considerably lower for the diagnosis based on the combined information on PME and clinical signs observed in the herd.     

Virulence of recent and former classical swine fever virus isolates evaluated by their clinical and pathological signs

The clinical diagnosis of classical swine fever (CSF) still caused problems to the veterinarians during the last decade. The primary CSF outbreak was often detected too late and, meanwhile, the virus had spread. Consequently, the recent classical swine fever virus isolates (CSFV) were suspected to be of low virulence. The purpose of the study was to quantify the virulence of four recent CSFV by evaluating the clinical and pathological signs caused by different CSFV. Pigs of the same breed and age group were inoculated intranasally with CSFV from recent epidemics in European Union (EU) member states. The CSFV used are registered in the data base of the EU Reference Laboratory for CSF and belong to different genotypes: 2.1, 2.2 and 2.3 respectively. Clinical signs of CSF were evaluated by using a score system suggested previously (Mittelholzer et al., 2000: Vet. Microbiol. 74, 293). For the evaluation of pathological lesions, a new pathological score was introduced. The four CSFV tested here were classified as moderately virulent in general, although one CSFV may cause different clinical courses, ranging from highly virulent to avirulent. This indicates the importance of additional factors in the host animal for virulence. Differences in the clinical and pathological signs between these four recent CSFV were rather minor, emphasizing that the genetic typing of CSFV is absolutely essential. Differences towards former CSFV (e.g. reference virus strain Alfort 187) were more pronounced, especially regarding the onset and duration of the disease, the occurrence of skin haemorrhages and pathological lesions of kidney, subcutis and serosae. It is concluded that clinical diagnosis of CSF is rather difficult in pigs up to 14 days post-CSFV infection using these four CSFV, emphasizing the need for careful differential diagnosis and the laboratory investigation for CSF at an early stage.     

猪瘟病毒持续感染与猪瘟预防控制

研究证明,在自然条件下,猪瘟病毒持续感染通常是在免疫力较低的情况下,由于环境中的病毒反复感染产生的,由于感染猪还有一定的免疫力,病毒虽然可以在其体内局部存留,但还不足以引起猪发病.一般情况下,感染猪虽然持续带毒,但不表现临床症状,然而却可以不断向外排毒,再次感染其他猪,污染环境;带毒的种猪可以通过母猪的胎盘和公猪的精液传播给仔猪,造成仔猪的先天免疫耐受,导致疫苗免疫失败.实验还证明,即使在良好的免疫状况下,反复多次人工感染猪瘟强毒也可造成持续感染.由此可见,猪瘟病毒持续感染是一个复杂的问题.     

猪瘟病毒FJFQ-39株的毒力鉴定

为探索一种相对客观、稳定的方法鉴定猪瘟病毒(CSFV)FJFQ-39株的毒力.本研究采用2×103TCID50的FJFQ-39株分别肌肉接种6头敏感猪,通过RT-nPCR 检测扁桃体和血液监测动物感染情况,对动物临床症状和病理变化进行系统评分,结合体温分析,判定病毒毒力.同时用相同剂量的石门株接种4头敏感猪作对照.FJFQ-39和石门接种猪的扁桃体和血液均检测到CSFV核酸;FJFQ-39接种猪的最大临床症状评分(CS)平均值为3.53.5±1.0、病理评分(PS)平均值为3.3±0.9(低于5),平均最高体温为39.3±0.2℃(低于40℃);石门接种猪的最大CS平均值为25.5±2.1、PS平均值为29.5±2.4(大于15),平均最高体温为41.8±0.2℃(高于41.0℃).实验结果表明:猪瘟病毒FJFQ-39株和石门株均成功感染了动物;评分系统结合体温测定评价CSFV毒力是可行的;FJFQ-39 属于低毒力株,而石门属于强毒株.     

Genetic typing of classical swine fever virus

Three regions of the classical swine fever virus (CSFV) genome that have been widely sequenced were compared with respect to their ability to discriminate between isolates and to segregate viruses into genetic groups. Sequence data-sets were assembled for 55 CSFVs comprising 150 nucleotides of the 5' non-translated region, 190 nucleotides of the E2 envelope glycoprotein gene and 409 nucleotides of the NS5B polymerase gene. Phylogenetic analysis of each data-set revealed similar groups and subgroups. For closely related viruses, the more variable or larger data-sets gave better discrimination, and the most reliable classification was obtained with sequence data from the NS5B region. No evidence was found for intertypic recombination between CSFVs. A larger data-set was also analysed comprising 190 nucleotides of E2 sequence from 100 CSFVs from different parts of the world, in order to assess the extent and global distribution of CSFV diversity. Additional groups of CSFV are evident from Asia and the nomenclature of Lowings et al. (1996) [Lowings, P., Ibata, G., Needham, J., Paton, D., 1996. J. Gen. Virol. 77, 1311-1321] needs to be updated to accommodate these. A tentative assignment, adapting rather than overturning the previous nomenclature divides CSF viruses into three groups with three or four subgroups: 1.1, 1.2, 1.3; 2.1, 2.2, 2.3; 3.1, 3.2, 3.3, 3.4. The expanding data-base of CSFV sequences should improve the prospects of disease tracing in the future, and provide a basis for a standardised approach to ensure that results from different laboratories are comparable.     

Neuropathologic study of experimental classical swine fever

The aim of this study was to report on the lesions occurring in the central nervous system (CNS) during experimental classical swine fever (CSF) to clarify the spatial and chronologic distribution of the lesions and virus antigen in the CNS. To learn more about the pathogenetic mechanisms of the lesions during CSF in the CNS and to investigate the role of the virus in these mechanisms, cellular infiltrates and infected cells have been characterized. Twenty-eight pigs were inoculated with the virulent CSF virus isolate Alfort 187 and slaughtered from 2 to 15 postinoculation days; 4 animals of similar background served as a control group. Immunohistochemistry, electron microscopy, and the transferase-mediated deoxyuridine triphosphate nick-end labeling method were used to detect viral antigens and apoptosis. The results showed the presence of nonpurulent meningoencephalitis, occasional microhemorrhages, and apoptosis of the lymphocytes forming the perivascular and interstitital infiltrate in swine with CSF. Macrophages appeared to display little involvement in CNS lesions. The infected cells observed at the early stage of disease were lymphocytes and microglial cells in the rostral portion of the telencephalon, with infection of these cells in other areas in the next stages. The relationship between these lesions and the presence of viral antigen varied according to the type of lesion: hemorrhages were not associated with the presence of antigen in endothelial cells, but infiltrate-cell apoptosis was temporally and spacially associated to viral infection. However, the link between viral infection and the presence of cell infiltrate was far from clear.     

Vaccinology of classical swine fever: from lab to field

There are two types of classical swine fever vaccines available: the classical live and the recently developed E2 subunit vaccines. The live Chinese strain vaccine is the most widely used. After a single vaccination, it confers solid immunity within a few days that appears to persist lifelong. The E2 subunit vaccine induces immunity from approximately 10-14 days after a single vaccination. The immunity may persist for more than a year, but is then not complete. The Chinese strain vaccine may establish a strong herd immunity 1-2 weeks earlier than the E2 vaccine. The ability of the Chinese vaccine strain to prevent congenital infection has not been reported, but the E2 subunit vaccine does not induce complete protection against congenital infection. Immunological mechanisms that underlie the protective immunity are still to be elucidated. Both types of vaccine are considered to be safe. A great advantage of the E2 subunit vaccine is that it allows differentiation of infected pigs from vaccinated pigs and is referred to as a DIVA vaccine. However, the companion diagnostic E(rns) ELISA to actually make that differentiation should be improved. Many approaches to develop novel vaccines have been described, but none of these is likely to result in a new DIVA vaccine reaching the market in the next 5-10 years. Countries where classical swine fever is endemic can best control the infection by systematic vaccination campaigns, accompanied by the normal diagnostic procedures and control measures. Oral vaccination of wild boar may contribute to lowering the incidence of classical swine fever, and consequently diminishing the threat of virus introduction into domestic pigs. Free countries should not vaccinate and should be highly alert to rapidly diagnose any new outbreak. Once a new introduction of classical swine fever virus in dense pig areas has been confirmed, an emergency vaccination programme should be immediately instituted, for maximum benefit. The question is whether the time is ripe to seriously consider global eradication of classical swine fever virus.     

猪瘟防制研究的现状及发展趋势

由于猪瘟 (Ｃｌａｓｓｉｃａｌｓｗｉｎｅｆｅｖｅｒ,简称ＣＳＦ)对养猪业的毁灭性打击 ,各养猪国家特别是ＣＳＦ存在国都高度重视对ＣＳＦ及其防制的研究。为此 ,各国都投入了大量的人力、物力与财力 ,做了大量的工作 ,并取得了很大的成绩。尽管消灭ＣＳＦ花费巨大 ,但所带来的收益明显大于防疫的支出。那些无猪瘟的国家对ＣＳＦ的研究也丝毫不敢松懈 ,除了禁止从ＣＳＦ存在国进口活猪、猪肉及猪肉制品 ,强化口岸检疫 ,密切监测有ＣＳＦ国家的疫情 ,建立健全ＣＳＦ疫情报告、监测、法律法规和扑灭措施等之外 ,也还继续开展对ＣＳＦ的研究工…     

临床猪病中猪蓝耳病和猪瘟的检测分析

为了解临床猪病中猪繁殖与呼吸综合征病毒和猪瘟的感染情况.本研究根据 GenBank 中已发表的相关序列,建立并应用两组 RT-PCR 方法,对 2007 年 6月至2009年 7 月期间收集于江苏、江西地区的 323 份临床猪病料进行了检测.结果显示 PRRSV 阳性率为 85.14%(275/323),HCY 阳性率为 56.66%(183/323),PRRSV 和 HCV 的混合感染率为 40.87%(132/323).表明在猪临床疾病中 PRRSV 和 HCV 普遍存在,且混合感染非常严重.     

The influence of maternal immunity on the efficacy of a classical swine fever vaccine against classical swine fever virus,genogroup 2.2, infection

In Thailand, where vaccination is routinely employed, there has been an increased incidence of chronic classical swine fever (CSF) outbreaks during the past decade. The major causative virus has been identified to be the moderate virulence, classical swine fever virus (CSFV) of the genogroup 2.2. An investigation was made into the efficacy of a CSF vaccine against this genogroup 2.2 challenge. Five-week-old pigs, grouped by their level of passive antibody titer were immunized with lapinized Chinese-strain CSF vaccine and challenged with CSFV genogroup 2.2, 13 days after vaccination. The group containing passive titers of lower than 64 at the time of immunization, had significantly higher number of CSFV-specific IFN-gamma secreting cells and was completely protected against the challenge. Interestingly, both cellular and antibody responses were inhibited in the pigs with the higher passive titer. Furthermore, following challenge, CSFV could be isolated from 50% of the pigs in this group. It was demonstrated that the CSF vaccine could induce complete protection in pigs, provided that the maternal derived titer at the time of vaccination was lower than 64. The result implied that an increase in CSFV outbreaks might be due to the inappropriate timing of vaccination as well as the nature of the CSFV genogroup 2.2.     

Descriptive epidemiology of the outbreak of classical swine fever in Catalonia (Spain), 2001/02

Spain suffered an outbreak of classical swine fever between June 14, 2001 and May 7, 2002, which affected 49 herds; this paper describes the epidemiological characteristics of the 39 herds that were affected in Catalonia, an area of high pig density in the north east of Spain. The outbreak took place in two waves, which affected first the province of Lleida and then Barcelona. A total of 291,058 animals were slaughtered, 59,595 belonging to infected herds; 22 of the infected herds were detected on the basis of clinical suspicion on the part of the farmer or farm veterinarian, and the other 17 were detected by surveillance methods. The transmission of the virus between herds was attributed to the movement of people in 23 per cent of the cases, to animals in 13 per cent, vehicles in 10 per cent, proximity 18 per cent, the pick-up service of the rendering plant in 8 per cent and slurry in 5 per cent; in the other nine herds (23 per cent) the route of entry of the disease could not be established. The viruses isolated in the two waves of the outbreak were 100 per cent homologous and belonged to subgroup 2.3. The origin of the outbreak remains unknown.     

使用猪瘟疫苗及“猪三联苗”的关键技术

猪瘟疫苗及“猪三联苗”是在我国养猪生产中使用几率最多和数量最大的疫苗，但我们发现在不少地方使用这些疫苗后仍然免疫效果不好，甚至免疫失败，查其主要原因是对疫病和疫苗的特点及其性能认识不足甚至误识，再是使用技术失误，为保证免疫效果，现就其关键技术以问答形式做如下叙述，以供在生产实践中应用。     

新型猪瘟疫苗研究现状

猪瘟(classical swine fever,CSF)是由猪瘟病毒(classical swine fever virus,CSFV)引起的一种以急性出血和发热为主要特征的烈性传染病,死亡率极高,对养猪业危害极大,已被国际兽疫局(OIE)列为A类动物传染病.许多国家已经针对该病施行了控制和根除措施,但因为生猪及其产品贸易的全球化、养猪业的集约化和野猪群中CSFV的持久性等原因,CSF仍然对世界养猪业构成很大威胁.