Modelo probabilístico de espalhamento de salmonelose em suínos

Abstract

The toxinfections caused by eating food contaminated with the bacillus of Salmonella represents a major concern for public health and for large producers of pork and derivatives. The presence of any Salmonella serovar in foods is enough to classify it as unfit for consumption, both domestically and internationally. The Salmonella is a bacterium that affects the animal’s intestinal tract, causing malaise, weight loss and death in consequence of infection. For a study of the dynamics of spreading disease in swine are developed mathematical models that provide the state of the population regarding the infection. The proposed model describes the dynamics of a population over time, divided into three classes of states regarding the presence or absence of the bacillus of Salmonella: Susceptible, Latent and Infected. This dynamics is governed by a system of ordinary differential equations, perturbed by the presence of random factors that pose a risk of infection to the farm. These factors are characterized as white noise whose impact on the dynamics is controlled by two constant functions, T1 and T2. The solution to the system of differential equations is obtained by the Runge-Kutta method of approximating 2a order, computationally implemented and simulated in different scenarios. The average rates of birth and contact were drawn from the literature and used as basis for parameters in the mathematical model. The results of computer simulations to calculate the probability of a farm infection levels reach any given time and observing the rules of management and creation.