Using mathematical model to understand the impact of various preventive and control measures on the dynamics of visceral leishmaniasis in Brazil

Visceral leishmaniasis (VL) is a zoonosis with global distribution. Its incidence has increased in Brazil in recent years, thus coming to represent a serious public and animal health problem. The strategies applied in Brazil, essentially consisting of diagnosis and culling of seropositive dogs, have not sufficed to control the disease. Thus, we used a mathematical model of differential equation to evaluate the efficacy of different strategies of prevent and control of VL in endemic areas of Brazil, in different coverages. Rates of elimination of seropositive dogs, use of insecticide-impregnated dog collars and vaccination of dogs were simulated. The results showed that all of the tested control strategies significantly contributed to reduce the prevalence of infection in both the canine and the human population. However, none of the simulated measures was able to fully eliminate the disease. Because the use of insecticide-impregnated collars directly affects the vector-related parameters and the force of infection, it is possible to understand their high level of efficacy as a control measure. Evaluating the efficacy of control measures in different scenarios of coverage allows for better analysis of those measures to be selected for actual implementation and thus contributes to the elaboration of programs for the control and prevention of VL, especially in high-priority endemic areas.