Risk factors for brucellosis seropositivity of goat herds in the Mexicali Valley of Baja California, Mexico

A case-control study was conducted in the Mexicali Valley to identify risk factors for goat-herd seropositivity for Brucella melitensis. Nineteen case herds (≥2 positive results with the 8% rose bengal plate test (RBT)) and 55 control herds (zero positive results in RBT), matched for herdsize and geographic location, were enrolled. Conditional logistic regression was used to construct a multivariable model of the odds of seropositivity using variables assessed in a questionnaire administered to goat ranchers. The final model for herd seropositivity included increased risk from importation of goats from other Mexican states, the presence of La Mancha breed does, and the presence of does born outside the herd. Increasing herdsize was also highly significant (p<0.01). In addition, a significant (p<0.05) positive association was found between the presence of seropositive dogs (as assessed by RBT) and seropositive goats on the same ranch.     

Pathological changes,distribution and detection of Brucella melitensis in foetuses of experimentally-infected does

BackgroundBrucellosis of goats is caused by Brucella melitensis. It is a re-emerging zoonotic disease in many countries due to transmission from domestic animals and wildlife such as ibex, deer and wild buffaloes.ObjectiveTo describe the pathological changes, identification and distribution of B. melitensis in foetuses of experimentally infected does.MethodsTwelve female goats of approximately 90 days pregnant were divided into 4 groups. Group 1 was exposed intra-conjunctival to 100 µL of sterile PBS while goats of Groups 2, 3 and 4 were similarly exposed to 100 µL of an inoculum containing 10⁹ CFU/mL of live B. melitensis. Goats of these groups were killed at 15, 30 and 60 days post-inoculation, respectively. Foetal fluid and tissues were collected for bacterial identification (using direct bacterial culture, PCR and immuno-peroxidase staining) and histopathological examination.ResultsBilateral intra-conjunctival exposure of pregnant does resulted in in-utero infection of the foetuses. All full-term foetuses of group 4 were either aborted or stillborn, showing petechiations of the skin or absence of hair coat with subcutaneous oedema. The internal organs showed most severe lesions. Immune-peroxidase staining revealed antigen distribution in all organs that became most extensive in group 4. Brucella melitensis was successfully isolated from the stomach content, foetal fluid and various other organs.ConclusionVertical transmission of caprine brucellosis was evident causing mild to moderate lesions in different organs. The samples of choice for isolation and identification of B. melitensis are stomach content as well as liver and spleen tissue.     

Isolation and sero-genomo-epidemiological studies on Brucella infection in dairy cattle in Meghalaya,India

In this study, we report the serological, bacteriological and whole genome sequencing data of a 6 years study of Brucella abortus in Meghalaya, India. Investigation of 3060 sera samples indicated overall prevalence of 6.4% by Rose Bengal Plate Test and 10.7% by ELISA. Considerably higher prevalence was observed among milk samples (17.5%, n = 362) and in blood samples (37.7%, n = 262) by direct PCR. Clinical samples (n = 94) from late abortion cases yielded 11 B. abortus isolates. Multi-locus sequence typing indicated circulation of single sequence type, ST1. Whole genome sequencing (n = 8) and phylogenomic analysis revealed close clustering of majority of isolates in two clusters alongwith genomes from other countries, indicating global relatedness among B. abortus. Taken together, the results of our study revealed the putative hotspot of infection in the dairy-dominant districts of the state and also calls for concerted One Health based action for prevention and control of this zoonotic disease.     

犬种布鲁氏菌研究进展

犬种布鲁氏菌属于6个经典种布鲁氏菌之一，为天然粗糙型，毒力较弱。长期以来，由于犬种布鲁氏菌对人类致病性较低，其危害一直被忽视。自1966年在美国发现该菌以来，已传播至世界多地。近年来，随着养犬业的不断发展及宠物犬数量的增多，犬布鲁氏菌病发病率不断上升，在某些地区已成为流行性疫病，且对人类公共卫生安全的威胁也日益加重。目前，犬种布鲁氏菌感染导致的犬布鲁氏菌病尚无可靠的诊断方法及有效的疫苗。鉴于此，在查阅相关文献的基础上，笔者对犬种布鲁氏菌的病原学、流行病学、致病机理、检测方法、疫苗研究等方面的相关研究进展进行综述，以期为犬布鲁氏菌病的深入研究和防控提供参考。     

布鲁氏菌OMP16对RAW264.7细胞凋亡与免疫活性的影响

旨在研究布鲁氏菌外膜蛋白OMP16对小鼠巨噬细胞RAW264.7细胞凋亡和免疫活性的影响及其机制探讨。以OMP16处理RAW264.7细胞为模型,通过MTT以及Hoechst法检测OMP16对细胞活力的影响,通过Western blot检测Caspase-3、GRP78、CHOP的表达情况,流式细胞术检测OMP16对细胞凋亡的影响以及RT-PCR检测免疫因子IL-1β、IL-6和TNF-α的变化。结果表明,OMP16能够影响RAW264.7细胞的活力,且有浓度依赖性;添加OMP16后能够显著增加凋亡标志因子Caspase-3的表达（P<0.001）,并促进RAW264.7细胞的凋亡;作用24、36 h之后,显著引起内质网应激标志蛋白GRP78、CHOP的表达;并且能显著上调IL-1β、IL-6、TNF-α等炎性因子的mRNA表达水平。布鲁氏菌OMP16能够诱导RAW264.7凋亡,OMP16显著引起内质网应激CHOP通路的激活。     

布鲁菌外膜蛋白基因Omp22克隆测序及生物信息学分析

根据GenBank中的布鲁菌属特异性基因序列Omp22设计1对引物,以牛布鲁菌（Brucella）通辽市分离菌株染色体DNA作为模板,进行PCR扩增。将其定向插入克隆载体PGEM-7Zf,综合利用生物信息学软件（Danman和Vector NTI）、数据库（Prosite和PDB）和网络服务器对外膜蛋白Omp22进行基本性质分析、三维结构预测和功能预测。结果显示,用PCR方法扩增的Omp22基因长度为639bp,编码212个氨基酸,预测其蛋白质的相对分子质量约为22 000,同时用于预测B细胞线性表位的柔韧性和亲水性参数得到综合阐释,生物信息学预测和分析结果可为研究在布氏菌致病及机体免疫应答中外膜蛋白Omp22的结构与功能的关系提供丰富资料。     

Comparison of agar gel immunodiffusion test, rapid slide agglutination test, microbiological culture and PCR for the diagnosis of canine brucellosis

The performance of the rapid slide agglutination test, with and without 2-mercaptoethanol (RSAT and 2ME-RSAT) and agar gel immunodiffusion test (AGID) was evaluated for the diagnosis of brucellosis in naturally infected dogs. The microbiological culture, PCR and clinical parameters were used as reference. A total of 167 dogs were clinically examined and tested by blood culture, culture of semen/vaginal swab and PCR in blood and semen/vaginal swab. According to the results observed the 167 dogs were divided into three groups: Brucella canis infected dogs (Group 1), B. canis non-infected dogs (Group 2) and dogs with suspected brucellosis (Group 3). The dogs were then tested by RSAT, 2ME-RSAT and AGID. Groups 1 and 2 were used to calculate the diagnostic sensitivity and specificity of the serological tests and the results observed in Group 3 were also discussed. The diagnostic sensitivity of RSAT, 2ME-RSAT and AGID was respectively 70.58%, 31.76%, and 52.94%. The diagnostic specificity of RSAT, 2ME-RSAT and AGID was respectively 83.34%, 100%, and 100%. In dogs with suspected brucellosis 15% were RSAT positive, none was 2ME-RSAT positive and 5% were AGID positive. Although the serological tests are the most commonly used methods for brucellosis diagnosis, a significant proportion of false-negative results were observed highlighting the importance of the direct methods of diagnosis, like blood culture and PCR to improve the diagnosis of canine brucellosis.     

Epidemiology,zoonotic aspects,vaccination and control/eradication of brucellosis in India

In India, brucellosis was first recognised in 1942 and is now endemic throughout the country. The disease is reported in cattle, buffalo, sheep, goats, pigs, dogs and humans. B. abortus biotype-1 in cattle and buffaloes and B. melitensis biotype-1 in sheep, goats and man are the predominant infective biotypes. The long-term serological studies have indicated that 5% of cattle and 3% of buffaloes are infected with brucellosis. Economic losses due to brucellosis in livestock are considerable in an agrarian country like India. There is no organised and effective brucellosis control programme in the country. With the indigenous development of serum and milk based ELISA kits, the population survey of the disease has been undertaken on a large scale in several states and plans for the control of the disease through calf-hood vaccination are being worked out. An innovative approach—Bovine Brucellosis Progressive Control Programme (BBPCP) is targeted to overcome the basic problems of ban on cow slaughter, distress sale of animals following the positive serological diagnosis of brucellosis and absence of a disease control strategy. The work plan for the implementation of BBPCP is presented.     

Eradication of bovine brucellosis in the 10th Region de Los Lagos,Chile

The process of Bovine Brucellosis Eradication that began in 1996 in the 10th Region de Los Lagos of Chile will be reviewed. The region comprises the most important dairy area of the country and it has the largest concentration of brucellosis infected herds. Based on the information gathered by an epidemiological surveillance system, the results of the eradication process for the years 1996 till 2001 are presented as rates of Milk Ring Test (MRT) positive dairies, rates of brucellosis reactors (bovines) in livestock markets and slaughterhouses, and the annual incidence and prevalence of brucellosis infected herds.

During the period the rates of positive dairies, bovine reactors in livestock markets and slaughterhouses, and the annual incidence and prevalence of infected herds have experienced a decrease, while the rate of bovine reactors in slaughterhouses has remained stable. Data on the preventive measures taken, such as vaccination of female bovines and Certification of Brucellosis Free Herds, are also shown. The surveillance system has allowed the detection of infected herds, while the measures of prevention and cleaning of infected herds have allowed a reduction in the incidence and prevalence of the infection by Brucella abortus.