Academic literature on the topic 'Brucellosis Brucellosis Brucellosis Brucellosis'

La brucellose est une maladie qui se transmet de l’animal à l’homme. Elle est causée par la bactérie Brucella. Lors de ma thèse, j’ai montré que Brucella persiste dans les cellules de la moelle osseuse des animaux infectés. Ces observations sont très importantes car la moelle est un organe responsable de la génération des cellules du système immunitaires et c’est la principale niche des cellules souches hématopoïétiques. Au cours de ma thèse, j'ai montré que la protéine de la membrane externe 25 de Brucella (Omp25) est capable de lier au récepteur SLAMF1, une molécule exprimée par les cellules souches hématopoïétiques. Cette interaction conduit à la génération d'un plus grand nombre de cellules myéloïdes par les cellules souches hématopoïétiques. Les cellules myéloïdes sont la niche préférée de Brucella. Ainsi, cette stratégie permet à la bactérie d'envahir l’hôte et d'établir une infection chronique de longue durée. SLAMF 1 apparaît comme une nouvelle cible thérapeutique pour le contrôle des maladies infectieuses chroniques, ce qui représenterait une avancée importante dans la génération de nouveaux médicaments<br>Brucellosis is a disease that is transmitted from animals to humans. It is caused by the pathogenic bacterium Brucella. During my thesis, I showed that Brucella persists in the bone marrow cells of infected animals. These observations are very important because the bone marrow is an organ of the immune system responsible for the generation of the immune cells, as it is the principal niche of hematopoietic stem cells. During my thesis, I showed that Brucella outer membrane 25 (Omp25) is able to bind SLAMF1, a hematopoietic stem cell molecule. This interaction leads to the production of more myeloid cells by the hematopoietic stem cell. Myeloid cells are the favorite niche of Brucella. Thus, this strategy allows the bacteria to invade the host and establish a long lasting chronic infection. SLAMF 1 appears as a new therapeutic target for controlling chronic infectious diseases, which would represent an important advance in the generation of new drugs

Previous economic analysis of brucellosis control in Mongolia provided a basis for further research. It was observed that there was a long tradition of brucellosis control in Mongolia but little knowledge on its effect on the spread of disease. This thesis addressed this gap and analysed the relationship between stated surveillance policy, the brucellosis prevalence in animals, and the brucellosis incidence in humans. The aim was to contribute to better understanding of the brucellosis surveillance policies applied in Mongolia and their effectiveness, and to draw conclusions and recommendations for control of brucellosis. Four aims were formulated providing steps for investigating the research question. The first two aims focused on (i) the establishment of the epidemiological patterns of brucellosis in Mongolia over the time period 1966 to 2002, and on (ii) the provision of a historical overview of the different strategies applied to the control of brucellosis in Mongolia over the same time period. The third aim was to assess the interactions between the spread of brucellosis and the surveillance strategies, and finally the forth aim was to issue recommendations about future surveillance policies for brucellosis. It was found that the published figures reflected the Brucellosis abortus incidence in the population that could be serologically tested. However, the population at risk (herders) with the main burden of disease, and suffering from Brucellosis melitensis, was underdiagnosed and not treated properly, additionally, the immunisation cam- paigns in small ruminants did not reach the critical vaccination level for eradication. Therefore, the diagnosis and treatment of Brucellosis melitensis in humans has to be assured at Soum (district) level. The current immunisation campaign has to be monitored and evaluated, and the knowledge of brucellosis in humans has to be recognised by policy makers, physicians and general population.

Brucellosis is endemic in many livestock worldwide especially developing countries. The aims of this study were to estimate the seroprevalence of bovine brucellosis and risk factors associated with the seropositivity in rural and peri-urban buffaloes and cattle populations of Sindh. Firstly, a cross sectional study was conducted to estimate the seroprevalence of bovine brucellosis in cattle and buffaloes of Sindh province, Pakistan. Serum samples (2600) were tested using Rose Bengal Plate Test. The overall seroprevalence of brucellosis in Sindh province was 13.96% (95% C.I.; 11.55 - 16.37). Of the 917 herds tested, 232 or 25.30% herds (95%C.I.; 22.51-28.24) were positive for brucellosis. The adult animals were 2.05 (95% C.I.; 1.14-3.68, P= 0.02) times more likely to test positive for brucellosis. The animals in a peri-urban dairy production system were 2.07 times (95%C.I.; 1.09-3.90, P = 0.03) times more likely have brucellosis. The species or sex of animal did not appear to affect the risk of seropositivity in cattle or buffalo in this population. Secondly, a cross sectional survey was conducted to understand the structure and composition of farms, animal husbandry and management practices in peri-urban dairy colonies in Karachi and farmers’ awareness of zoonoses. The mean herd size was 93.58 animals and 88.01% of these animals were female buffaloes. Of 326 farms surveyed, only 37.42% were able to associate animals with transmission of diseases in human. The characteristics of peri-urban dairy farms in Karachi are discussed. Thirdly, the value of FTA® cards in detecting the Brucella DNA in milk samples was estimated by determining the detection limits of genus specific ERI PCR assay for FTA® cards and comparing the PCR results from whole sediments taken from culturing pooled milk samples with taking sediment on FTA® cards. The detection limits of this method ranged from 6.6 x 103 cfu/ml for B. abortus to 7.17 x 106 cfu/ml for B. suis. Assuming the results of ERI PCR for the whole sediment as gold standard (method 1), the method using sediment on FTA® cards as test samples (method 2) showed a diagnostic sensitivity of 81.44% (95% C.I.; 75.54-87.33) but a poor diagnostic specificity of 42.86% (95%C.I.; 16.95-68.78). The kappa value, κ, was 0.14 (p = 0.02) demonstrating a poor agreement between the two methods. Lastly, 181 bulk milk samples were used to estimate the herd level prevalence of bovine brucellosis in Landhi dairy colony, Karachi. The ERI PCR was used to test these samples. The herd prevalence was estimated as 92.26% (95% C.I.; 88.34-96.19). For each level (50 animals) increase in herd size, the risk of herd being brucellosis positive increases by 2.38 times. The herds that have a male animal for breeding are 0.09 times less likely to have brucellosis. The history of abortion, presence of small ruminants or the regions of animal purchase don’t appear to have any association with the risk of brucellosis at a herd level in this population at LDC, Karachi. A high seroprevalence of bovine brucellosis in livestock population in Sindh and a very high herd level prevalence in peri-urban dairy farms in particular poses a serious threat to the public health and livestock production in Sindh, Pakistan.

Disease management along the boundaries of wildlife reserves is a growing conservation problem worldwide, as infected wildlife can migrate outside protected areas and pose a threat to livestock and human health. The bison Bison bison population in Yellowstone National Park has long been infected with Brucella abortus, the bacterium causing bovine brucellosis. Concern over migratory bison transmitting B. abortus to cattle herds on lands adjacent to Yellowstone has led to proposals for bison vaccination. Model simulations suggest that vaccination is unlikely to eradicate B. abortus from Yellowstone bison but could be an effective tool for reducing the level of infection and eliminating unpopular management practices such as lethal culling. The culling of Yellowstone bison to reduce the risk of brucellosis transmission to cattle is negatively affecting long-term bison conservation because of difficulties in diagnosing actively infected animals. Age-specific serology and B. abortus culture assays from slaughtered bison were used to develop a diagnostic tool to estimate whether particular animals are infective. Findings suggest that active B. abortus infection is age-dependent, which allows true infection probabilities to be estimated based on age and quantitative diagnostic tests. Active brucellosis infection was associated with below-average nutritional condition, with the intensity of B. abortus infection being influenced by seasonal reductions in dietary protein and energy. The reproductive strategy of Yellowstone bison is linked with the seasonal availability of food, which increases bison fitness but may have consequences for B. abortus infection. Seasonal food restriction may also influence the ability of vaccinated bison to recall protective immune responses when later exposed to B. abortus. The rate of fat metabolism was an important factor influencing cell-mediated responses. Thus, individual variation and the seasonal availability of food may reduce vaccine efficacy when vaccination is applied at the population level. Consequently, effective management practices will require a diverse range of integrated methods, which include maintaining separation of livestock and wildlife, managing habitat to reduce brucellosis transmission, and reducing disease prevalence in wildlife. The long-term success of these management practices will depend on sound science and support of the stakeholders involved.

Brucella abortus st. RB51 is a rough mutant of smooth st. 2308 devoid of O-side chain and resistant to rifampin. The purpose of this investigation was to study the behavior and effects of viable st. RB51 organisms in inoculated mice and cattle and to further substantiate the lack of O-side chain antigens in this strain. A single injection of live st. RB51 persisted in BALB/C mice up to 28 days. A secondary exposure was cleared in 7-21 days. One or 2 injections of st. RB51 did not induce detectable titers of anti-O-side chain antibodies, although antibody titers to st. RB51 whole cell and cytoplasmic antigens were detected. Mice infected with st. RB51 alone or followed by infection with st. 2308, demonstrated a very strong reaction to a 14-18 Kd antigen which was believed to be the core of the LPS complex. When st. RB51 was administered after injection of st. 2308 the response to the core determinants were inhibited. One vaccination with st. RB51 was able to significantly protect mice against challenge with st. 2308 at one and four weeks post challenge. Two st. RB51 vaccinations were able to protect mice as well as one vaccination at one week post challenge but protection increased by four weeks post challenge. Strain RB5l was able to survive in cattle a for at least twenty-two days. The organism remained stable, rifampin resistant, and may have induced minor amounts of transient anti-O-side chain antibodies in some cows late in the experiments.<br>Master of Science

Feral swine are a nuisance species across the United States that costs around $1.5 billion each year in agricultural, environmental, and personal property damages. In the last ten years the population of feral swine is estimated to have quadrupled and novel population control methods are needed. Furthermore, feral swine are known carriers of zoonotic diseases such as brucellosis, which threatens both livestock biosecurity and public health. Recombinant multimeric gonadotropin-releasing hormone (mGnRH) has been previously used as a subunit vaccine to induce immunocontraception in feral pigs. However, potent adjuvants and large amounts of purified antigen are needed to elicit a robust anti-GnRH immune response and current delivery methods are limited. Brucella suis strain VTRS2 can be used as a novel platform to deliver mGnRH without the use of antibiotic resistant markers. Strain VTRS2 was created by deletion of the LPS biosynthesis gene wboA as well as the leuB gene required for leucine biosynthesis inside the nutrient-depleted intracellular environment occupied by Brucella. Mutations in wboA are known to attenuate Brucella strains such as the vaccine strain B. abortus RB51, however strain RB51 is rifampin resistant and has poor efficacy in swine. Strain VTRS2 confers significant protection against B. suis challenge in mice and additionally shows evidence of protection in feral swine. Furthermore, the mGnRH antigen can be delivered using the pNS4 plasmid (which expresses leuB under its native promoter) thus maintaining the plasmid in strain VTRS2 under leucine-deficient conditions while expressing recombinant antigen in the host. The murine model was used to determine the clearance kinetics of strain VTRS2-mGnRH and to measure vaccine efficacy against challenge by virulent B. suis 1330. Subsequently the effects of the VTRS2-mGnRH vaccine on fertility were assessed in breeding trials in mice. Strains VTRS2 and VTRS2-mGnRH were found to be protective against virulent Brucella suis challenge. Strain VTRS2-mGnRH elicited an anti-mGnRH antibody response in vaccinated mice, though an effect on fertility was not observed. An improved vaccine against brucellosis in swine, which also confers immunocontraception without the introduction of antibiotic resistance, could become an important tool in the management of this nuisance invasive species.<br>Ph. D.