一例牛口蹄疫疫苗免疫过敏反应的诊治

口蹄疫是由口蹄疫病毒引起的偶蹄动物的一种急性、热性、高度接触性一类传染病,具有发病急、蔓延快、传播广、危害大等特点。我国对本病采取了100%注射疫苗强制免疫的措施,有效地控制了本病的发生及蔓延。然而在注苗免疫过程中,因个体差异等原因,个别家畜往往出现不同程度的过敏反应,有时因救治不及时或治疗方法不当造成死亡,给养殖户带来一定的经济损失,也影响了防疫工作的有效推进。文章通过一例牛口蹄疫免疫过敏病例的救治,介绍了牛在接种口蹄疫疫苗后可能出现的应激反应,并提出了解救措施,为及时、有效处理口蹄疫疫苗应激反应提供参考。     

Residual foot-and-mouth disease virus antibodies in French cattle and sheep six years after the vaccination ban

A serological survey was carried out on French cattle to establish a reference pattern of residual vaccine antibodies and non-specific reactions against the foot-and-mouth disease virus 6 years after the ban on vaccination and in the absence of any foot-and-mouth disease outbreak. Most of the multi-vaccinated cattle still displayed high titres of antibodies and up to 50% of those which had received a single injection still had antibodies. Non-specific reactors were also recorded among animals born during and after 1991. Most of them displayed low titres close to the threshold. Sheep were also tested and, as for cattle, 4.6% of non-specific reactors were recorded, with titres close to the threshold for two-thirds of them. As part of these animals have been resampled and retested, sera revealed negative confirming that these animals are true non-specific reactors. Serological testing as a mean of FMD control should take these facts into account.     

Outbreak of foot-and-mouth disease in Northern Benin during the 1990-1991 dry season

An outbreak of foot-and-mouth disease damaged the North-Benin during the 1990-1991 dry season (November to May). Coming from outside the Benin, it spread out very quickly in the country essentially because of trans-humant herds. No measures have been taken to limit this sickness which is endemic and which regularly exhibits outbreaks in Benin. Antibodies to types A, O and SAT2 of the foot-and-mouth disease virus were detected in the sera during this outbreak.     

Disinfection of foot-and-mouth disease and African swine fever viruses with citric acid and sodium hypochlorite on birch wood carriers

Transboundary animal disease viruses such as foot-and-mouth disease virus (FMDV) and African swine fever virus (ASFV) are highly contagious and cause severe morbidity and mortality in livestock. Proper disinfection during an outbreak can help prevent virus spread and will shorten the time for contaminated agriculture facilities to return to food production. Wood surfaces are prevalent at these locations, but there is no standardized method for porous surface disinfection; commercial disinfectants are only certified for use on hard, nonporous surfaces. To model porous surface disinfection in the laboratory, FMDV and ASFV stocks were dried on wood coupons and exposed to citric acid or sodium hypochlorite. We found that 2% citric acid was effective at inactivating both viruses dried on a wood surface by 30 min at 22°C. While 2000 ppm sodium hypochlorite was capable of inactivating ASFV on wood under these conditions, this chemical did not meet the 4-log disinfection threshold for FMDV. Taken together, our data supports the use of chemical disinfectants containing at least 2% citric acid for porous surface disinfection of FMDV and ASFV.     

Airborne spread of foot-and-mouth disease in Saskatchewan, Canada, 1951-1952.

Farms affected with foot-and-mouth disease during the epidemic in Saskatchewan, in 1951-1952, for which the origin of virus was not known or uncertain, were studied to determine if infection could have been introduced by the airborne route. A short-range Gaussian plume dispersion model was used to estimate the concentration of virus downwind and the dose available for individual animals. The investigation suggested that a large virus source due to infected pigs in a feedlot in January 1952 could have been responsible for airborne dispersion northwestwards downwind to farms up to 20 km distant. Subsequent spread from these farms was to neighboring farms and was influenced by the local topography of a creek. The dispersion model could be used for predicting airborne spread if foot-and-mouth disease should occur.     

The Role of Management Segregations in Controlling Intra-herd Foot-and-mouth Disease

Transmission of foot-and-mouth disease virus (FMDV) by aerosol spread can occur over considerable distances. However, this is less effective in hot, dry environmental conditions, and a detailed study of an outbreak within a large dairy herd in Saudi Arabia has shown that contact spread is the main mode of transmission within a herd: both physical and spatial barriers curtailed the course of disease across the farm. Hence, the speed and path of an outbreak can be altered by changing the positioning of spatial or physical barriers. Extending the distances between pens, increasing the number of farm pens, decreasing the number of animals within the pens, and placing pens of well-protected stock between those of susceptible stock, can all contribute to the control of FMD involving contact and short-distance aerosol spread. Such management techniques offer a cost-effective supplement to control by vaccination.     

The epidemic of foot-and-mouth disease in Saskatchewan, Canada, 1951-1952.

The epidemic of foot-and-mouth disease in Saskatchewan in 1951 and 1952 was studied in order to determine origins of outbreaks and methods of spread. The epidemic was initially considered to be vesicular stomatitis and foot-and-mouth disease was not recognized until February 1952, three months after the initial infection. The reports prepared at that time were reviewed in order to obtain details of the numbers of animals infected and the source and date of infection for the outbreaks. Methods of spread were rated according to their likelihood. The introduction of infection by an immigrant through his clothes as well as by sausage was possible. The sequence of events from the first outbreak to the spread from a feedlot/packing plant and from a dairy farm, which failed to report the disease, were clarified. Methods of spread included movement of animals, animal products and people and the airborne route. Milk delivery and artificial insemination did not result in spread of infection. The quarantine of affected farms reduced spread by animals and deterred visits by people. The original diagnosis of vesicular stomatitis was due to misinterpretation of a lesion in an inoculated horse. Laboratory tests established the presence of foot-and-mouth disease. The limited extent of the epidemic, despite the delay in diagnosis, is attributed to (i) the low density of cattle, (ii) few infected pigs and hence less airborne virus and (iii) absence of waste food feeding and milk collection in addition to the limited quarantine imposed.     

抗口蹄疫病毒策略研究进展

口蹄疫是偶蹄动物的一种烈性传染病,可使世界范围内的畜牧业遭受严重的经济损失。该病的防控方法主要包括扑杀、销毁病畜及其同群动物,对疫区内其它易感畜群和受威胁区的易感动物立即紧急接种对应型号的口蹄疫疫苗,除此之外,还需要有一些新的紧急抗病毒策略来弥补疫苗的不足,从而为易感动物及未感染动物提供及时的保护,作者着重综述了抗口蹄疫病毒策略的研究进展,主要包括IFN的应用、反义技术的应用、RNA干扰技术的应用三方面内容。     

Modelling the spread of foot-and-mouth disease in Australia

Preparedness for an incursion of an exotic animal disease is of key importance to government, industry, producers and the Australian community. An important aspect of Australia's preparedness for a possible incursion of foot-and-mouth disease is investigation into the likely effectiveness and cost-efficiency of eradication strategies when applied to different regional outbreak scenarios. Disease modelling is a tool that can be used to study diseases such as foot-and-mouth disease to better understand potential disease spread and control under different conditions. The Australian Government Department of Agriculture, Fisheries and Forestry has been involved with epidemiologic simulation modelling for more than 10 years, and has developed a sophisticated spatial model for foot-and-mouth disease (AusSpread) that operates within a geographic information system framework. The model accommodates real farm boundary or point-location data, as well as synthesised data based on agricultural census and land use information. The model also allows for interactions between herds or flocks of different animal species and production type, and considers the role that such interactions are likely to play in the epidemiology of a regional outbreak of foot-and-mouth disease. The user can choose mitigations and eradication strategies from those that are currently described in Australia's veterinary emergency plan. The model also allows the user to evaluate the impact of constraints on the availability of resources for mitigations or eradication measures. Outputs include a range of maps and tabulated outbreak statistics describing the geographic extent of the outbreak and its duration, the numbers of affected, slaughtered, and, as relevant, vaccinated herds or flocks, and the cost of control and eradication. Cost-related outputs are based on budgets of the value of stock and the cost of mitigations, each of which can be varied by the user. These outputs are a valuable resource to assist with policy development and disease management.     

Airborne transmission of foot-and-mouth disease virus from Burnside Farm,Heddon-on-the-Wall,Northumberland, during the 2001 epidemic in the United Kingdom

The results of a detailed assessment of the atmospheric conditions when foot-and-mouth disease (FMD) virus was released from Burnside Farm, Heddon-on-the-Wall, Northumberland at the start of the 2001 epidemic in the UK are consistent with the hypothesis that the disease was spread to seven of the 12 farms in the immediate vicinity of the source by airborne virus, and airborne infection could not be ruled out for three other premises; the remaining two premises were unlikely to have been infected by airborne virus. The distances involved ranged from less than 1 km up to 9 km. One of the farms which was most probably infected by airborne virus from Burnside Farm was Prestwick Hall Farm, which is believed to have been key to the rapid spread of the disease throughout the country. In contrast, the results of detailed atmospheric modelling, based on a combination of clinical evidence from the field and laboratory experiments have shown that by assuming a relationship between the 24-hour average virus concentrations and subsequent infection, threshold infection levels were seldom reached at the farms close to Burnside Farm. However, significant short-term fluctuations in the concentration of virus can occur, and short-lived high concentrations may have increased the probability of infection and explain this discrepancy.     

A型塞尼卡病毒检测方法及疫苗研究进展

A型塞尼卡病毒（Senecavirus A,SVA）也称为塞尼卡谷病毒（Seneca Valley virus,SVV）,属于小RNA病毒科塞尼卡病毒属成员。SVA主要引起猪的水泡性疾病,与口蹄疫、水泡性口炎、猪水泡病等临床症状相似,可导致新生仔猪急性死亡,严重影响养猪业发展。自2015年广东省发生SVA感染以来,中国多省份陆续有该病发生的报道。当前,中国因猪群缺乏针对SVA的免疫屏障,加之该病传染性较强,存在大范围暴发的潜在风险。如何有效防控SVA感染是迫切需要解决的问题。目前已开发出多种SVA诊断方法用于进行实验室及现场条件下早期的鉴别诊断。SVA的分离鉴定、原位杂交和免疫组化可用于检测病原体的存在及其与组织内形态学变化关系;血清学诊断方法包括基于不同结构蛋白的间接ELISA方法、竞争ELISA方法、均相光激化学发光免疫技术和病毒中和试验,用免疫学方法检测抗体有助于了解SVA感染进程,是临床诊断的主要手段;病毒核酸检测方法主要有PCR技术、等温扩增技术、基因组测序等分子生物学技术,在病毒感染的早期快速检测及检测新发病毒中具有重要作用。目前仍无商品化疫苗预防SVA感染,但科研人员已研发出了灭活疫苗、弱毒疫苗、核酸疫苗和亚单位疫苗等多种具有潜力的候选疫苗。笔者系统总结了SVA检测方法及疫苗研发的最新进展,以期为SVA感染的防控提供参考依据。     

Foot-and-mouth disease eradication efforts in the Republic of Korea

On March 20, 2000, a suspected vesicular disease in cattle was reported to the National Veterinary Research and Quarantine Service (NVRQS) of the Republic of Korea. This represented the index case of a foot-and-mouth disease (FMD) outbreak, which spread through several provinces. The Republic of Korea had been free of FMD for 66 years prior to the reintroduction of the virus and had recently suspended imports of pork and pork products from neighboring Japan owing to a reported FMD outbreak in that country. The Korean outbreak was ultimately controlled through the combination of preemptive slaughter, animal movement restrictions, and a strategy of ring vaccination. The purpose of this paper is to review the current FMD situation in Korea in the aftermath of its 2000 epizootic and how it may affect future efforts to eradicate or reduce risk of reintroduction of the disease into Korea.     

Foot-and-mouth disease: an assessment of the risks facing New Zealand

Although New Zealand has never had a case of foot-and-mouth disease (FMD), the threat that this disease poses to the economy of this country has long been recognised. The unprecedented global spread of FMD caused by the type-O PanAsia strain, culminating in the outbreak that occurred in the United Kingdom in early 2001, has refocussed the concerns of biosecurity agencies worldwide. The 3 lines of defence against exotic disease incursions in this country are border controls, surveillance and incursion response capability. This article reviews the pathogenesis, virus survival, routes of infection and methods of spread of FMD virus, and in the light of recent international developments, presents a summary of the major risks of introduction and dissemination of FMD virus and the risk-management measures in place for this country.     

Interferon inducers and foot-and-mouth disease vaccines: influence of two synthetic polynucleotides on antibody response and immunity in guinea pigs and swine.

Polyriboadenylic-polybouridylic acid enhanced the immunological response of guinea pigs to aqueous foot-and-mouth disease virus vaccine. Polyriboninosinic-polyribocytidylic acid enhanced the early antibody production of swine to oil emulsified foot-and-mouth disease virus vaccine. Polyriboninosinic-polyribocytidylic acid alone did not stimulate resistance to foot-and-mouth disease in swine.     

口蹄疫转基因植物可饲疫苗研究进展

口蹄疫是由口蹄疫病毒引起的一种急性热性高度接触性传染病,给畜牧业造成极大的经济损失,疫苗是预防和控制该病的有效方法。近年来,转基因植物可饲疫苗由于其易于生产、成本低廉、使用方便和安全等诸多的优点成为口蹄疫新型疫苗的研究热点。文章综述了口蹄疫转基因植物可饲疫苗的研究现状,介绍了其原理和方法,分析了其优缺点和改进方法,并对其应用前景进行了展望。     

Experimental evaluation of foot-and-mouth disease vaccines for emergency use in ruminants and pigs: a review

Changes to foot-and-mouth disease (FMD) control policies since 2001 mean that emergency vaccination must be considered more readily as a control measure in the future. Since field application of vaccine for emergency use has only rarely been applied, the effectiveness of single dose administration, as a control measure in an outbreak situation, is poorly understood. In this review we consider all the available experimental data from studies utilizing either experimental or readily available, commercially produced vaccines, in order to assess their likely effectiveness as an additional means of controlling FMD transmission and spread in an emergency. Overall it is concluded that such vaccines offer an additional and valuable means of FMD control for both ruminants and pigs. They are able to reduce clinical disease, sub-clinical infection and excretion and onward transmission of virus. However, to be most effective, vaccination should be rapidly applied to give maximum opportunity for immunity to develop. We also identify areas for future research and emphasize the importance of vaccine efficacy studies in providing data for models that can help to predict the efficacy of differing FMD control strategies.     

The epidemiology of foot-and-mouth disease: implications for New Zealand

Foot-and-mouth disease is an acute, highly communicable disease affecting cloven-hoofed animals, both domesticated and wild. It may well be the most contagious disease known in the animal kingdom. The key features that contribute to this include its ability to gain entry and initiate infection through a variety of sites, the small infective dose, the short incubation period, the release of virus before the onset of clinical signs, the massive quantities of virus excreted from infected animals, its ability to spread large distances due to airborne dispersal, and the persistence of the virus in the environment. These features, plus the ability of the virus to be disseminated through the movements of animals, animal products, people, and plant and equipment makes the disease very difficult to control. New Zealand has never experienced a foot-and-mouth disease epidemic, and the economic consequences of an outbreak would be disastrous, due to the eradication costs, the loss of productivity and the impact on the export of animals and animal products. The smuggling of meat products, embryos or semen into the country are perceived as the most likely ways in which the disease could be introduced. The New Zealand Ministry of Agriculture and Fisheries therefore operates a two-tier system of defense against foot-and-mouth disease. The first tier involves border protection through stringent import controls to prevent the entry of infectious material. If this barrier is breached, an emergency response programme is activated, involving a stamping-out eradication strategy. This paper attempts to draw on overseas historical outbreak experiences and research findings to gain insights into the epidemiology of foot-and-mouth disease as it would relate to New Zealand.     

Pacheco's parrot disease in macaws of the Lisbon's Zoological Garden. Description of an outbreak, diagnosis and management, including vaccination

The Lisbon's Zoological Garden, Portugal, has maintained for many years a large collection of psittacine birds without any serious health problems. Unexpectedly, in April 1999, a total of nine macaws died after a short period of illness. Clinical signs consisted mainly of anorexia, ruffled feathers and yellowish droppings. A herpesvirus was isolated from brain, trachea, lung, liver, spleen, kidney and intestine of each of the examined dead birds, confirming that all animals succumbed during viraemia. Serotyping of the isolate in cross neutralization tests with reference sera prove that the outbreak was caused by serotype 3 of Pacheco's parrot disease herpesviruses. An autogenous, formalin-inactivated vaccine with adjuvant (aluminium hydroxid gel) was prepared from one of the isolates and injected intramuscularly 14 days and six weeks after the onset of mortality in an attempt to protect the remaining psittacine birds in the zoo from the disease. The autogenous vaccine was well tolerated and was able to rapidly stop virus spread and morbidity and mortality among the psittacine birds. Follow-up studies demonstrate that all nine blood samples from vaccinated birds obtained nine month' after the second vaccination contain neutralizing antibodies. Twenty five month' after vaccination two out of four serum samples were still antibody positive. No herpesvirus was isolated from faecal samples nine and twenty five months after the onset of the outbreak. These data prove that the autogenous vaccine played a major role in containing a severe outbreak of Pacheco's parrot disease in a large collection of psittacine birds.     

Epidemiological investigations of the 2001 foot-and-mouth disease outbreak in Argentina

A total of 2126 herds, an attack rate of 0.82 per cent, were affected during an epidemic of foot-and-mouth disease in Argentina in 2001. The spatial and temporal distribution of the epidemic was investigated using nearest-neighbour and spatial scan tests and by estimating the frequency distributions of the times to intervention, and distances and times between outbreaks. The outbreaks were clustered and associated significantly (P<0.01) with herd density; 94 per cent were located in the Pampeana region, where the cattle population is concentrated, which had an attack rate of 1.4 per cent. The clustering results suggested that the virus had spread locally between outbreaks. Most of the outbreaks were separated by one day and the maximum distance between outbreaks was almost 2000 km, indicating that the infection spread rapidly over large distances. The index outbreak was detected more than 15 days after the primary outbreak, and restrictions on the movement of cattle were probably not enforced until about one month after infection occurred. As in other major epidemics, the period between the first outbreaks and the effective application of control strategies was probably crucial in determining the progress of the epidemic.     

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.