Establishment of risk classification index for animal brucellosis by stochastic models

Brucellosis is a zoonotic disease of animal origin, which not only causes serious harm to the development of animal husbandry but also poses a threat to human health. Risk classification of animal brucellosis is very important and serves as the basis for decision-making of disease prevention and control. In this study, a probability model and continuous time Markov chain models are proposed to establish the importing probability and extinction probability for different production modes of farms, respectively. The main findings show that the importing probability has the most significant impact on the measures of quarantine and testing. For the extinction probability, when the environmental factors and indirect transmission are taken into account, the related parameters are sensitive, while the initial values of the infections are sensitive in the case that the environmental factors and indirect transmission are absent. Finally, the model is extended to the regional level and the data from epidemiological investigations are used to quantitatively assess the extinction probabilities of the three counties in a certain city.