Risk factors of bovine tuberculosis in cattle in rural livestock production systems of Ethiopia

This study shows a representative stratified cluster sample survey of the prevalence of comparative intradermal tuberculin test in cattle from four regions in Ethiopia. Using a cut-off for positivity of 2 mm, it assesses possible risk factors for tuberculin-positive reaction in cattle. Seventy-three villages in 24 kebeles (administrative units) were randomly selected, from which 2216 cattle from 780 owners were tested. In addition, 450 of these cattle owners were interviewed for risk factor assessment. Ninety-nine percent of the tested cattle in this rural livestock production system were traditional zebus. The individual overall prevalence of cattle bovine tuberculosis (BTB)e was 3%, with the highest found in Meskan Mareko, in Central Ethiopia (7.9%) and the lowest in Woldia, in the North East edge of the Rift Valley (1.2%). Generalised Linear Mixed Models (GLMM) with random effect on kebeles was used to analyse risk factors of cattle reactors and human tuberculosis (TB) infection. Purchase of cattle and presence of other livestock in the herd were statistically significant, with OR: 1.7, p-values of 0.03 and OR: 2, p = 0.05, respectively. Family members diagnosed with TB or showing clinical signs of extra-pulmonary TB (EPTB) were reported in 86 households (19%). None of the assessed potential risk factors of disease transmission between cattle and human (food consumption, livestock husbandry and presence of BTB-positive cattle) were statistically significant.     

牛结核病的诊断与预防概况

结核病是一种人畜共患传染病,危害严重.本文着重对牛结核病的病原学、临床症状、病理变化及诊断情况作了系统的介绍,并对防治情况简要分析.     

监测牛结核病时应注意的问题

本文对监测牛结论核病时应当注意的问题进行了较为详细地探讨,为同行提供了参考.     

Prevalence of bovine tuberculosis and animal level risk factors for indigenous cattle under different grazing strategies in the livestock/wildlife interface areas of Zambia

A cross-sectional study was conducted to investigate the prevalence and animal level risk factors for bovine tuberculosis (BTB) in indigenous cattle of the livestock/wildlife interface areas in Zambia. A total of 944 cattle from 111 herds were investigated. The comparative intradermal tuberculin test (CIDT) was used to identify reactor animals for BTB. Animal level data on sex, age, parity and body condition score were registered. The overall animal prevalence of BTB as determined by the CIDT was 6.8% (95% CI: 4.2, 9.5%). In Lochinvar and Blue Lagoon areas, animal level prevalence were observed at 5.2% (95% CI: 2.2, 8.2%) and 9.6% (95% CI: 6.1, 13.2%), respectively. Kazungula, an area outside the livestock/wildlife interface, had a prevalence of only 0.8% (95% CI: 0.0, 2.3%). The age of the animal, its body condition score and the type of management system, were predictive of its BTB status. The study revealed that BTB was relatively high in the livestock/wildlife interface areas of Lochinvar and Blue Lagoon compared to Kazungula. These findings should raise a serious public health concern considering the extent to which the communities of the study areas are in contact with their animals and the levels at which they use untreated milk.     

论牛结核病诊断和防治措施

由于牛结核病一旦在畜群中发生就难以根除且在临床检查中很难发现异常,所以就牛结核病的诊断提出笔者的看法,并对其防治提出直接的见解。     

鹿结核病野毒株与卡介苗差异基因基因文库的构建

应用四碱基限制性内切酶对鹿结核病流行株和卡介苗基因组分别酶切,以鹿结核流行株酶切产物为testerDNA,卡介苗酶切产物为driver DNA,testerDNA接头连接后与driver DNA进行抑制性消减杂交。将获得的消减PCR产物与pMD-18连接,JM109感受态细胞,进行蓝白斑筛选。结果表明,RsaI酶切产生的酶切产物在0.1～2.0 kb之间,将消减PCR产物克隆后,挑取208个转化子,构建了鹿结核病流行株与卡介苗的差异基因文库。结果表明,应用抑制性消减杂交技术,构建鹿结核病流行株与卡介苗基因组差减文库,可为鹿结核病自然感染和卡介苗免疫的鉴别诊断及鹿结核病的综合防治奠定基础。     

Improving protective efficacy of BCG vaccination for wildlife against bovine tuberculosis

Possums are a wildlife vector of bovine tuberculosis in New Zealand. Vaccination of possums with BCG is being considered as a measure to control the spread of bovine tuberculosis to cattle and deer. Delivery via oral bait is feasible but BCG is degraded in the stomach. The aim was to determine whether ranitidine (Zantac) would reduce gastric acidity and enhance the efficacy of intragastrically administered BCG. A dose of 75 mg reduced gastric acidity for at least 4 h. Thus, possums were vaccinated intragastrically with BCG after receiving 75 mg ranitidine or ranitidine or BCG alone, as controls, before challenge with virulent Mycobacterium bovis. Proliferative responses of blood lymphocytes to M. bovis antigens after vaccination were significantly higher in possums given ranitidine/BCG compared to controls and seven weeks after challenge they had significantly lower lung weights and spleen bacterial counts than ranitidine alone controls. Vaccination with BCG alone only gave a reduction in loss in body weight. Agents that reduce gastric acidity may be useful in formulating BCG for oral bait delivery to wildlife for vaccination against bovine tuberculosis.     

结核分支杆菌HSP65 DNA疫苗的制备和重组蛋白的原核表达

结核分支杆菌分子量为65ku的热应激蛋白(HSP65)是一种非常重要的抗原，为了研制结核病核酸疫苗，构建编码HSP65DNA，并将其分别克隆到原核和真核载体中进行了表达。以标准结核分支杆菌H37Rv基因组DNA为模板，用PCR法扩增出HSP65基因，经限制性内切酶消化后，插入真核表达栽体pJW4303中，获得重组质粒pJW-HSP65。同时将HSP65基因插入原核表达栽体pET-22b( )，获得重组质粒pET22b-HSP65。将pET22b-HSP65重组质粒转化大肠杆菌蛋白酶缺陷型菌株BL21(DE3)／PolysS，用IPTG诱导，进行蛋白表达。结果表明，经酶切鉴定和序列测定证实插入片断为目的基因HSP65，构建成功了真核重组质粒pJW-HSP65即可作为结核病DNA疫苗。经SDS-PAGE检验证明可以在大肠杆菌细胞中高效表达，将表达蛋白进行纯化，作为保护性结核杆菌抗原以便检测HSP65DNA疫苗的免疫效果。     

Strategy for the detection and differentiation of Mycobacterium avium species in isolates and heavily infected tissues

The members of Mycobacterium avium species, comprising M. avium subsp. paratuberculosis, M. a. hominissuis, M. a. avium, M. a. silvaticum, are currently the most prevalent opportunistic pathogenic mycobacteria causing mycobacterial infection in animals and humans. The ability to distinguish between these subspecies is of relevance for proper diagnosis and control programmes of the diseases. The aim of this study was to design a fast and specific PCR strategy for the detection and differentiation of M. avium subspecies from the solid plate cultures for use in routine veterinary diagnosis. We have developed a multiplex PCR based on IS900, IS901, IS1245 and the dnaJ gene. This method allows the detection of M. a. paratuberculosis, M. a. hominissuis and M. a. avium/M. a. silvaticum in one PCR reaction and theoretically enables mixed infections of M. a. paratuberculosis and M. a. avium or M. a. paratuberculosis and M. a. hominissuis to be revealed. The sensitivity of this multiplex PCR is 10(3)CFU for each bacterial strain in one PCR reaction, which also enabled the use of this test directly for DNA isolated from the tissue of the heavily infected sheep.     

牛结核病诊断方法研究进展

牛结核病主要是由牛分支杆菌引起的一种人兽共患传染病,近年来发病率有所上升,给奶牛养殖业造成了巨大的危害。目前,牛结核病的诊断仍然以传统的迟发性变态反应试验为主,其他诊断方法有根据临床症状和病理变化诊断、抗酸染色法、细菌分离培养法、PCR法、血清学方法、淋巴细胞转化试验、γ-干扰素试验和菌体成分检测法等。为了净化该病,必须提高诊断方法的敏感性和特异性。文章对这些诊断方法及其优缺点做了概述,并指出结核病普查检测时,比较合理的诊断方式是迟发性变态反应试验和间接ELISA法同时运用。