RESUMO
BACKGROUND: Bovine brucellosis is a zoonotic disease that causes substantial economic losses and has a strong impact on public health. The main objective of this paper is to determine the risk factors for new infections of Brucella abortus on Colombian cattle farms previously certified as being free of brucellosis. A case-control study was conducted by comparing 98 cases (farms certified as brucellosis-free for three or more years but became infected) with 93 controls (farms that remained brucellosis-free during at least the previous three years). The farms were matched by herd size and geographical location (municipality). Information was obtained via a questionnaire completed by veterinary officers through a personal interview with the herd owners. RESULTS: Two-thirds of the herds (67%) were dairy herds, 16% were beef herds, and 17% were dual-purpose (beef and milk) herds. After exploratory univariate analysis, all explanatory variables with a p-value of ≤0.20 were included in a logistic regression model using the forward stepwise method to select the model with the best goodness of fit. The significant risk factors were the replacement of animals from farms not certified as brucellosis-free compared to replacement from certified brucellosis-free farms (OR = 4.84, p-value < 0.001) and beef cattle farms compared to dairy cattle farms (OR = 3.61, p-value = 0.017). When herds with and without artificial insemination were compared, it was observed that farms that used natural breeding with bulls from non-certified herds had a higher risk than farms using artificial insemination (OR = 2.45, p-value = 0.037), but when the bulls came from brucellosis-free farms, farms with natural breeding were less affected (OR = 0.30, p-value = 0.004) than farms using artificial insemination, whether with frozen semen from certified brucellosis-free herds or fresh semen from uncontrolled herds. The latter is commonly sold to neighbouring farms. CONCLUSIONS: The government should make efforts to inform farmers about the risks involved in the introduction of semen and replacement heifers from farms that are not certified as brucellosis-free and to establish measures to control these practices.
Assuntos
Brucelose Bovina/epidemiologia , Brucelose Bovina/prevenção & controle , Criação de Animais Domésticos/normas , Animais , Cruzamento/métodos , Brucella abortus/isolamento & purificação , Brucelose Bovina/transmissão , Bovinos , Colômbia/epidemiologia , Criopreservação , Indústria de Laticínios , Feminino , Inseminação Artificial/métodos , Inseminação Artificial/veterinária , Masculino , Fatores de Risco , Preservação do SêmenRESUMO
Bovine brucellosis is an important zoonosis caused by Brucella abortus that negatively impacts livestock productivity. In 2001, Brazil launched a new national program aimed at eradicating animal brucellosis that included large-scale studies of the prevalence and risk factors to support strategic decision-making. These studies were implemented by the animal health authorities and were underpinned by the scientific coordination of the University of São Paulo and the University of Brasília. The state-level results were published and revealed important differences in herd prevalence among regions. The risk factors varied across states and did not clearly explain the observed spatial disease spread. This study used a consolidated herd-level database of 14 states and 17,100 herds, from the prevalence surveys' data, to gain insights into herd profiles and cattle production practices that might be associated with the risk of brucellosis. At the time of data collection, the study area comprised just over 56 million bovine females aged over 24 months and approximately 1.8 million herds. After an exploratory univariable analysis, all factors with p≤0.20 were included in a multiple logistic regression model, using the design-based method in order to take herd sampling weights into account. The number of females in the herd markedly increased the risk of infection; compared with smaller herds (less than 30 females), the odds ratio was 3.42 [CI 95% 2.98-3.91] for herds with 31 to 100 females, 5.68 [4.92-6.55] for herds with 101 to 400 females, and 13.14 [10.94-15.78] for herds with more than 400 females. The risk was higher for extensive cattle production farms (OR=1.23 [1.07-1.42]) and for farms that purchased replacement stock from cattle traders (OR=1.27 [1.08-1.47]) or directly from other farms (OR=1.19 [1.07-1.32]). The exclusive use of artificial insemination (OR=0.57 [0.4-0.81]) and regular veterinary support (OR=0.68 [0.6-0.77]) appeared to be protective factors. These findings are consistent with the regional prevalence trends observed in the study and provide key guidance for the planning of the national effort to control and eradicate brucellosis. High vaccination coverage of heifers is recommended, especially when targeted to areas where large-scale extensive cattle production predominates. The smaller, more intensive herds, are good candidates for disease accreditation schemes.
Assuntos
Brucelose Bovina/epidemiologia , Brucelose Bovina/prevenção & controle , Medicina Veterinária/estatística & dados numéricos , Criação de Animais Domésticos/normas , Animais , Anticorpos Antibacterianos/sangue , Brasil/epidemiologia , Brucella abortus/isolamento & purificação , Brucelose Bovina/microbiologia , Brucelose Bovina/transmissão , Bovinos , Estudos Transversais , Feminino , Humanos , Modelos Logísticos , Razão de Chances , Densidade Demográfica , Prevalência , Fatores de Risco , Estudos SoroepidemiológicosRESUMO
Relata-se a ocorrência de um surto de brucelose em um rebanho de aproximadamente 1000 animais, livre da doença há 18 anos, certificado pelo Ministério da Agricultura, Pecuária e Abastecimento desde 2006. Dois animais reagiram aos testes sorológicos de diagnóstico por ocasião dos procedimentos de recertificação em 2008. Após o sacrifício deles, Brucella abortus, biovariedade 1, amostra não vacinal, foi isolada e identificada por meio de provas bioquímicas e de biologia molecular (PCR AMOS). A origem do agente no rebanho é de difícil determinação. No entanto, a adoção de procedimentos preconizados pelo Programa Nacional de Controle e Erradicação da Brucelose permitiu evitar a disseminação da enfermidade. Ocorrências como essas, em que rebanhos livres foram infectados após anos sem a ocorrência de brucelose, nunca haviam sido relatadas no Brasil.
A Brucellosis outbreak is reported in a bovine herd free from the disease for over 18 years, officially free since 2006. One heifer and one cow tested positive in serological tests for the 2008 annual recertification in a herd of almost 1000 animals. Isolation and identification by biochemical tests and molecular biology (AMOS PCR) confirmed the infection by a Brucella abortus biovar 1 field strain. It wasn't possible to find the source of the infection. However, adoption of standard procedures prescribed by the Brazilian National Brucellosis and Tuberculosis Control and Eradication Program hindered the spread of the disease. This is the first report of a Brucella infection in an officially Brucellosis-free bovine herd in Brazil.
Assuntos
Animais , Bovinos , Brucella abortus , Brucelose Bovina/diagnóstico , Brucelose Bovina/transmissão , Doenças dos Bovinos/diagnóstico , Doenças dos Bovinos/transmissão , Surtos de Doenças/veterináriaRESUMO
Relata-se a ocorrência de um surto de brucelose em um rebanho de aproximadamente 1000 animais, livre da doença há 18 anos, certificado pelo Ministério da Agricultura, Pecuária e Abastecimento desde 2006. Dois animais reagiram aos testes sorológicos de diagnóstico por ocasião dos procedimentos de recertificação em 2008. Após o sacrifício deles, Brucella abortus, biovariedade 1, amostra não vacinal, foi isolada e identificada por meio de provas bioquímicas e de biologia molecular (PCR AMOS). A origem do agente no rebanho é de difícil determinação. No entanto, a adoção de procedimentos preconizados pelo Programa Nacional de Controle e Erradicação da Brucelose permitiu evitar a disseminação da enfermidade. Ocorrências como essas, em que rebanhos livres foram infectados após anos sem a ocorrência de brucelose, nunca haviam sido relatadas no Brasil.(AU)
A Brucellosis outbreak is reported in a bovine herd free from the disease for over 18 years, officially free since 2006. One heifer and one cow tested positive in serological tests for the 2008 annual recertification in a herd of almost 1000 animals. Isolation and identification by biochemical tests and molecular biology (AMOS PCR) confirmed the infection by a Brucella abortus biovar 1 field strain. It wasn't possible to find the source of the infection. However, adoption of standard procedures prescribed by the Brazilian National Brucellosis and Tuberculosis Control and Eradication Program hindered the spread of the disease. This is the first report of a Brucella infection in an officially Brucellosis-free bovine herd in Brazil.(AU)
Assuntos
Animais , Bovinos , Brucelose Bovina/diagnóstico , Brucelose Bovina/transmissão , Brucella abortus , Doenças dos Bovinos/diagnóstico , Doenças dos Bovinos/transmissão , Surtos de Doenças/veterináriaRESUMO
In this paper a model of bovine brucellosis spread is analyzed. This model consider four epidemiological classes: susceptibles, aborting infectious, infectious carriers and immune by vaccination. The per capita death rates of susceptibles, aborting and carriers are interpreted as slaughtering rates and they are time variable in order to maintain the size of the herd constant. A description of the evolution of the disease at the beginning of the epizootiological outbreak is given by means of singular perturbation techniques. We obtain a threshold parameter for the outbreak of the disease and a description of the asymptotic behavior of the model by using a theorem of Markus on asymptotically autonomous systems.
Assuntos
Brucelose Bovina/transmissão , Modelos Estatísticos , Aborto Animal , Animais , Brucelose Bovina/epidemiologia , Portador Sadio/veterinária , Bovinos , Simulação por Computador , Surtos de Doenças/veterinária , Suscetibilidade a Doenças , Feminino , Matemática , Gravidez , Complicações Infecciosas na Gravidez/veterinária , Vacinação/veterináriaRESUMO
This paper describes how path analysis, a quantitative analytical technique, was used to evaluate details on the epidemiology of bovine brucellosis in a discrete geographic area of Baja California Norte, Mexico. The steps involved in the analysis are discussed and details are presented for refining and improving the bovine brucellosis control program in this geographic area.
Assuntos
Brucelose Bovina/prevenção & controle , Animais , Vacina contra Brucelose , Brucelose Bovina/transmissão , Bovinos , Feminino , Inseminação Artificial/veterinária , Masculino , Modelos TeóricosRESUMO
The world literature was searched to document the variables known to affect the initiation, spread, maintenance, and/or control of bovine brucellosis. Each variable was classified into 1 of 3 categories, depending upon whether it was related to the animal population, to management, or to the biology of the disease. These variables were documented and categorized as the initial step for a quantitative path analysis on the epidemiology of bovine brucellosis in a defined geographic area in northern Mexico.