Characteristics of foot and mouth disease virus in Taiwan

Since March 1997 two strains of foot and mouth disease (FMD) virus have found their way into Taiwan, causing severe outbreaks in pigs and in Chinese yellow cattle. Outbreaks occurred in March 1997 were caused by a pig-adapted virus strain (O/Taiwan/97) which did not infect other species of cloven-hoofed animals by natural route. The epidemic spread over the whole region of Taiwan within two months and the aftermath was 6,147 pig farms infected and 3,850,746 pigs destroyed. In June 1999, the second strain of FMD virus (O/Taiwan/99) was isolated from the Chinese yellow cattle in the Kinmen Prefecture and in the western part of Taiwan. By the end of 1999, Chinese yellow cattle were the only species infected and those infected cattle did not develop pathological lesions. Seroconversions of serum neutralization antibody and on non-structural protein (NSP) antibodies were the best indicators for infection in non-vaccinated herds. The infected animals, however, excreted infectious levels of virus to infect new hosts. Based on the detection of the specific antibody to FMD virus, and virus isolation from oesophageal-pharyngeal (OP) fluid samples, ten herds of Chinese yellow cattle located in Kinmen and Taiwan were declared to have been infected. During the period of January to March 2000, however, five outbreaks caused by FMD virus similar to the O/Taiwan/99 virus occurred in four prefectures of Taiwan. The infected species included goats, Chinese yellow cattle and dairy cattle. Those outbreaks have caused high mortality in goat kids under two weeks old and also developed typical clinical signs of infection in dairy cattle.     

人参茎叶皂甙对口蹄疫病毒灭活疫苗免疫后抗体产生的影响

分别用人参茎叶皂甙(GSL)、白油或两者混合物作为免疫佐剂,与Asia-Ⅰ型口蹄疫病毒(FMDV)灭活疫苗混合免疫小鼠,检测免疫后的血清特异性抗体水平.结果表明,GSL具有佐剂作用,能显著促进机体产生抗FMDV抗体的水平,其佐剂作用呈量效关系.当GSL和白油混合形成复合佐剂时,具有组合效应,能产生比2种佐剂单独应用时更强的抗体效价;且GSL和白油混合产生的组合效应主要促进IgG2a和IgG2b的产生.     

Improvement of the immune response to foot and mouth disease virus vaccine in calves by using Avridine as adjuvant.

The epidemiological analysis of the cattle population during the eradication plan of foot and mouth disease (FMD) in Argentina clearly indicated a higher incidence of the disease in animals within their first year of age. It is important to improve the efficacy of the vaccination in those animals. In a previous report, we have shown the effect of an immunomodulator, Avridine (Avr), in the enhancement of the immune response elicited by FMD virus (FMDV) vaccines in experimental hosts [Berinstein, A., Pérez Filgueira, M., Schudel, A., Zamorano, P., Borca, M., Sadir, A.M., 1993. Avridine and LPS from Brucella ovis: effect on the memory induced by foot-and-mouth disease virus vaccination in mice. Vaccine 11, 1295-1301]. In this report, we analyze the effect of Avr in the improvement of the anti-FMDV immune response elicited in young animals immunized with a tetravalent vaccine. The anti-FMDV antibody response was evaluated using a liquid-phase blocking sandwich ELISA (LPBE) [Smitsaart, E.N., Zanelli, M., Rivera, I., Fondevila, N., Compaired, D., Maradei, E., Bianchi, T., O'Donnell, V., Schudel, A.A., 1998. Assessment using ELISA of the herd immunity levels induced in cattle by foot and mouth disease oil vaccines. Prev. Vet. Med 33, 283-296] while the cellular response was detected using an antigen specific lymphoproliferative test [Zamorano, P., Wigdorovitz, A., Chaher, M., Fernández, F., Sadir, A., Borca, M., 1994. Localization of B and T cell epitopes on a synthetic peptide containing the major immunogenic site of FMDV O1 Campos. Virology 201, 383-387]. The results show that, while no differences were detected in the cellular response, the anti-FMDV antibody reaction was significantly (<0.05) higher in animals immunized with the immunogen containing Avr. At 90 days post vaccination, 89-100% of the animals immunized with Avr presented predicted protection (PP) higher than 82% while just 50-61% of the animals immunized with vaccine without immunomodulator presented that characteristic. Also, it is shown that the increase in the anti-FMDV antibody titre in animals immunized with the vaccine containing Avr was mediated by an increase in the levels of both IgG1 and IgG2 which presented a significative correlation with LPELISA antibodies titres. It is concluded that the addition of Avr in the FMDV vaccines improve the immune status of the calves, the cattle population that suffers the highest epidemiological risk.     

Recent outbreak of foot and mouth disease in Ivory Coast]

An outbreak of foot and mouth disease (FMD) due to SAT2 occurred among cattle, sheep and pigs in C?te-d'Ivoire. The morbidity and mortality were low so vaccination of only high value livestock in intensive production systems was suggested.     

Clinical picture and differential diagnosis of foot and mouth disease in cattle

Foot-and-mouth disease (FMD) in cattle is characterized by the formation of vesicles and erosions in the mouth, teats and feet. Despite extremely high morbidity, mortality in adults is usually very low, however up to 50% of calves dies due to cardiac involvement or secondary infections. This paper describes the signs of FMD in cattle as well as those of other diseases which causes similar lesions in this species.     

Clinical signs and differential diagnosis of foot and mouth disease in pigs

FMD in pigs is primarily a foot disease. It is dominated by rather painful formation of vesicles in the epidermis of the feet (coronary band, interdigital clefts, bulbs) combined with severe lameness. Complications will be seen as detachment of the hoof and secondary infection of disrupted aphthae which may cause purulent arthritis of the pedal joint. Concerning differential diagnosis are to be considered all cases of acute lameness, vesicle-formation as typical lesions of exudative epidermites of pemphigus in the course of infections with S. hyicus or S. aureus as well as degenerative changes after selenium-intoxication, specially near the coronary band, sometimes linked with exungulation.     

牲畜口蹄疫强制免疫操作应注意事项

安全有效的疫苗免疫,是目前控制和扑灭口蹄疫的主要技术措施之一。我国对牲畜口蹄疫实行强制免疫制度,即对生猪、牛、羊等偶蹄动物全面实施口蹄疫强制免疫。这一措施收到了防控口蹄疫的理想效果,但在实施口蹄疫强制免疫过程中也存在着一些问题,应引起高度重视。     

母源抗体对猪口蹄疫疫苗免疫应答的影响

用液相阻断ELISA(Liquid phase blocking ELISA,LPB-ELISA)和正向间接血凝(Indirect hemagglutination test,IHAT)2种血清学试验方法对规模化饲养猪群仔猪的口蹄疫母源抗体、母源抗体的传递途径、消长规律、母/仔代特异抗体相关性及母源抗体对口蹄疫疫苗免疫的影响进行了研究和分析。结果表明,2种血清学方法均没有从未吸吮初乳的新生仔猪中检出特异抗体;在吸吮初乳后的仔猪血清中可检出特异性抗体,并于10日龄左右抗体效价升至峰值,而后随着日龄的增加,特异性抗体的效价呈明显的线性下降,母源抗体半衰期约为10～20d,至45～60日龄母源抗体效价降至不完全保护带(lgX<1.8)或更低;仔猪母源抗体水平与母体特异抗体水平呈正相关。通过对不同日龄仔猪接种口蹄疫疫苗后抗体水平检测发现,仔猪体内较高水平的母源抗体对疫苗免疫应答具有明显或一定的负面影响。     

猪口蹄疫O型合成肽与油乳灭活疫苗免疫后抗体水平的比较

为明确猪口蹄疫O型合成肽疫苗与油乳灭活疫苗免疫后的抗体水平,将65头51日龄四元杂交猪随机分为5组(13头/组),其中AA组和DD组分别为油乳灭活疫苗A及合成肽疫苗D的二次免疫组,AAA组及DDD组为相应疫苗的3次免疫组,在首免或二免后4周加强免疫,采用阻断ELISA方法检测首免后2、4、6、8、10周及12周(WPI)特异性抗体的阻断率。研究结果表明,在6 WPI,DD组及DDD组抗体阻断率开始上升,接近或达到峰值,其阻断率分别为94.5%(13/13)和97.1%(13/13),随后DD组抗体水平基本维持稳定,而DDD组抗体水平在10 WPI缓慢攀升至峰值,随后下降至65.7%(11/13);AA组和AAA组在6 WPI尽管抗体阻断率也呈上升趋势,且在10 WPI达到或接近峰值,分别为53.0%(8/13)及45.3%(6/13);综上,与猪口蹄疫O型油乳灭活疫苗2次免疫或者3次免疫相比,合成肽疫苗不仅可使机体获得较高水平的抗体,且抗体维持时间较长。     

猪亚洲Ⅰ型口蹄疫免疫程序试验

口蹄疫是世界动物卫生组织（OIE）规定的A类烈性动物传染病，我国列为一类动物传染病。口蹄疫共有7种血清型，亚洲Ⅰ型是其中一种。目前国内还没有猪亚洲Ⅰ型口蹄疫免疫程序，通过对105头猪进行亚洲Ⅰ型口蹄疫母源抗体和免疫抗体的检测，观察其抗体消长规律，以制定比较符合实际的、科学的猪亚洲Ⅰ型口蹄疫免疫程序。     

Participatory appraisal of foot and mouth disease in the Afar pastoral area, northeast Ethiopia: implications for understanding disease ecology and control strategy

Foot and mouth disease (FMD) is the most economically important disease of livestock that still affects extensive areas of the world. This study described the use of participatory appraisal tools such as pair-wise ranking, matrix scoring and proportional piling to assess the perception of livestock keepers about the clinical signs and epidemiological features of cattle diseases with particular emphasis on FMD. Strong agreement among informant groups (W?=?0.710; P?=?0.000) in pair wise ranking indicated that the diseases were common problem to all the selected districts. Matrix scoring of disease indicators/signs also showed strong agreement (W?=?0.504 to 0.955; P?=?0.000) that implied significant current veterinary knowledge by Afar pastoralists. Age specific means of annual incidence rates estimated by proportional piling were significantly (P?<?0.05) different but negatively correlated for FMD, CBPP and pasteurellosis. However, correlation was not significant for anthrax, blackleg and other important diseases. Age specific means of annual mortality was significantly (P?<?0.05) but negatively correlated for FMD, CBPP, pasteurellosis and other important cattle diseases with correlation coefficients of ?0.72, ?0.81, ?0.8 and ?0.55, respectively. However, correlation (r?=?0.12) was not significant for anthrax and not correlated at all for blackleg. This study indicated that pastoralists have detailed knowledge about their livestock health problems, and hence the combined use of participatory appraisal and conventional methods is essential for an ultimate disease control strategy.     

牛、羊口蹄疫免疫抗体监测分析

口蹄疫(FMD)只有通过疫苗免疫才能有效预防,因而掌握本地区牛羊口蹄疫的免疫抗体水平情况,对减少该类疫病的发生有重要意义。本文即对南平市近三年牛羊口蹄疫免疫抗体监测结果进行分析总结。     

新疆周边国家的口蹄疫疫情调查分析

口蹄疫（FMD）俗称“口疮”、“蹄癀”，是由口蹄疫病毒引起的偶蹄兽的一种急性、热性、高度接触性传染病。发病地区的活畜产品不但禁止上市，而且出口贸易被禁止或限制及对其采取封锁、隔离、免疫接种和检疫消毒等措施，必然造成重大的经济损失。及时了解疫区与非疫区分布对我国的防治工作具有重大的意义，本文主要对新疆周边国家的口蹄疫疫情状况进行概述及危害分析。     

Improved immune response by ID-pVAC: a secretory DNA vaccine construct delivered by PLG micro particles against foot and mouth disease in guinea pigs

Foot and mouth disease (FMD) outbreaks usually have devastating effects on the economy of countries were disease is endemic due to direct and indirect cost; most of them related to international trade embargoes of animals and animal products. Although currently used inactivated vaccine provides protection, it has several drawbacks like short duration of immunity, and the requirement for containment facilities. A DNA vaccine construct which expresses the secretary antigens, delivered through micro particles could be one of the alternate approaches to overcome these limitations. Present study is envisaged to prepare a DNA vaccine construct containing the VP1 sequence of FMDV serotype O in pVAC vector. DNA vaccine was formulated by adsorbing plasmid DNA construct on cationic micro particles and administered in guinea pigs @25 μg DNA vaccine construct per animal intramuscularly. Sera samples collected were analyzed by sandwich ELISA and SNT, shown enhanced immune response in PLG adjuvanted DNA vaccine. MTT and 3H Thymidine incorporation have shown good CMI responses to PLG adjuvanted DNA. When challenged with 100 gpid50 of homologous virus 5 of the six animals were protected.     

猪口蹄疫O型病毒ORMF8测毒试验

用中国农科院兰州兽医研究所统一提供的猪口蹄疫O型灭活疫苗效检攻毒用种毒ORMF8,在3个企业同时用架子猪进行测毒,分别测得猪的最小感染量(MID)和猪的半数感染量(ID 50).3家单位测得的MID和ID 50分别为10 -6.0 /2 mL,10 -8.2 /2 mL;10 -7.0 /2 mL,10 -7.0 /2 mL;10 -6.0 /2 mL,10 -7.5 /2 mL.将所有实验动物统计计算,MID约为10 -6.3 /2 mL,ID 50约为10 -7.6 /2 mL.从这些数据得出,该试验1 MID约为20 ID 50.     

羊亚洲Ⅰ型口蹄疫免疫程序试验

口蹄疫是哺乳动物高度接触性烈性传染病，OIE列为A类传染病之首。2005年口蹄疫亚洲Ⅰ型在中国的少数地区暴发，那么研究FMD Asia—Ⅰ免疫程序，就成为了兽医工作的当务之急。     

A simulation model of intraherd transmission of foot and mouth disease with reference to disease spread before and after clinical diagnosis.

Intraherd transmission of foot and mouth disease virus (FMDV) was examined using a simulation model for a hypothetical 1,000-cow dairy, assuming clinical diagnosis was made when at least 1% (10 cows) or 5% (50 cows) had clinical signs of FMD, I index case cow, and transition state distributions for the latent, subclinically infectious, and clinically infectious periods of FMD calculated from published data. Estimates assumed for the number of animal-to-animal contacts (k) adequate for transmission ranged from 0.6 to 9.0 per hour (13.7-216.0 per day). A total of 40,000 iterations (5,000 for each scenario, assessing 4 adequate contact rates and 2 detection criteria) were run. The model predicted that FMD would not be diagnosed in the herd until 10.0-13.5 days after the index case cow had become infected, at which time between 65% and 97% of the cows (646-967 cows) to nearly 100% (978-996 cows) would already have become infected with the virus, if the number of cows showing clinical signs of FMD at the time of diagnosis were 10 or 50, respectively. At the time of diagnosis, the simulated number of infectious cattle varied substantially from 82-472 to 476-537 cows, depending on adequate contact rate and whether the diagnosis was made when 10 or 50 animals were showing clinical signs, respectively. The simulated number of infectious cows increased rapidly during the first few days after diagnosis. In the scenario where at least 10 cows showing clinical signs was necessary before a clinical diagnosis was made, each day after diagnosis, the number of infectious animals increased by nearly 100 to more than 200 cases per day up to day 5, assuming 0.57-9.0 animal-to-animal contacts per hour, respectively. Results obtained when it was assumed that at least 50 clinical cases were present at the time of diagnosis showed smaller relative increases because nearly one-half of the herd was projected to be infected at the time of diagnosis. From these results, it is clear that once an individual in a herd becomes infected with FMDV, herd infectivity is not static, rather it accelerates as would be expected as long as there are sufficient susceptible animals to sustain the increasing transmission rate, after which time the rate at which new infections occurs will diminish. Results indicate that biosecurity strategies aimed at minimizing both intraherd and interherd contact will be critical in minimizing the spread of FMD before the initial diagnosis is made. In addition, simulations suggest that very early clinical diagnosis of FMD and effective isolation or depopulation and disposal will be critical in limiting the number of infectious animals capable of transmitting the virus to other herds and thus in timely control of an epidemic. Early diagnosis will rely on early virus detection from animals in the preclinical phase of infection, rather than waiting for clinical signs to manifest in sufficient numbers to be noticed and to warrant investigation.