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A cross-sectional study was conducted on bovine brucellosis in a sample of 173 medium/small-scale cattle farmers in a tropical region of Ecuador. A total of 173 milk tank samples were collected and analyzed through an indirect ELISA. A survey was also applied to each farm to collect information on herd management, evaluate the level of knowledge about the disease and estimate the risk that bovine brucellosis on those farms could represent for public health. The apparent prevalence among farms was 11.5% (95% CI: 6.7%-16.2%). The medium farms had a prevalence significantly higher (23.8%,95% CI: 10.9%-36.6%, p<0:0001) than the small farms (7.6%, 95% CI: 4.5%-9%). Two multivariable analysis were conducted to identify risk factors associated with bovine brucellosis or reproductive disorders. Medium farms had 3.7 more odds to be infected than the small farms (OR: 3.7, 95% CI: 1.39-9.84, p = 0:008). Incineration/burial of abortion material was identified as a protective factor (OR: 0.4, 95% CI: 0.14-0.98, p = 0:04). Farm size and brucellosis were identified as risk factors for the occurrence of reproductive disorders. Only 25% of the farmers were aware of bovine brucellosis. Unpasteurized curdled milk was regularly consumed and marketed on 112 farms of which 14 were positive for bovine brucellosis. Highly at-risk practices, such as manipulation of aborted fetuses were also reported. These results indicate that there is a need to develop public health education programs targeted at medium/small-scale farmers in Ecuador. [ABSTRACT FROM AUTHOR]

Dirichlet process mixtures are flexible nonparametric models, particularly suited to density estimation and probabilistic clustering. In this work we study the posterior distribution induced by Dirichlet process mixtures as the sample size increases, and more specifically focus on consistency for the unknown number of clusters when the observed data are generated from a finite mixture. Crucially, we consider the situation where a prior is placed on the concentration parameter of the underlying Dirichlet process. Previous findings in the literature suggest that Dirichlet process mixtures are typically not consistent for the number of clusters if the concentration parameter is held fixed and data come from a finite mixture. Here we show that consistency for the number of clusters can be achieved if the concentration parameter is adapted in a fully Bayesian way, as commonly done in practice. Our results are derived for data coming from a class of finite mixtures, with mild assumptions on the prior for the concentration parameter and for a variety of choices of likelihood kernels for the mixture. [ABSTRACT FROM AUTHOR]

We develop methodology and complexity theory for Markov chain Monte Carlo algorithms used in inference for crossed random effects models in modern analysis of variance. We consider a plain Gibbs sampler and propose a simple modification, referred to as a collapsed Gibbs sampler. Under some balancedness conditions on the data designs and assuming that precision hyperparameters are known, we demonstrate that the plain Gibbs sampler is not scalable, in the sense that its complexity is worse than proportional to the number of parameters and data, but the collapsed Gibbs sampler is scalable. In simulated and real datasets we show that the explicit convergence rates predicted by our theory closely match the computable, but nonexplicit rates in cases where the design assumptions are violated. We also show empirically that the collapsed Gibbs sampler extended to sample precision hyperparameters significantly outperforms alternative state-of-the-art algorithms. [ABSTRACT FROM AUTHOR]

Bovine brucellosis is a worldwide zoonotic disease that still burdens several countries in the Mediterranean, Asia, Africa and Latin America. Although the disease is present in Ecuador, the Galapagos Islands seem to be free from the disease based on a survey conducted in 1997 where all tested animals showed negative results. This study aimed at estimating the probability of freedom from brucellosis in this Ecuadorian province in 2014. A survey was implemented on the three main cattle-producing islands of the province: Santa Cruz, Isabela and San Cristóbal. Thirty-three cattle farms and 410 cattle were tested for brucellosis using the Rose Bengal test and indirect ELISA. All animals showed negative results for both tests. Probability of freedom was estimated at 98%, 91% and 88% for Santa Cruz, Isabela and San Cristóbal, respectively, considering a herd-level design seroprevalence of 20% and animal-level design seroprevalence of 15%, and assuming a perfect specificity of the survey. The negative results found in 1997 and present surveys suggest that the Galapagos Islands are free from bovine brucellosis. [ABSTRACT FROM AUTHOR]