Cost assessment of optimal control strategy for brucellosis dynamic model based on economic factors.

In recently years, brucellosis between humans and animals in China has shown signs of outbreak again. Brucellosis always takes a heavy toll on human health and profitability of livestock industry, but for farmers, the purpose of breeding is to make profits. Therefore, the optimal control strategy that can maximize the profits of farmers and effectively control brucellosis is needed. It is important to understand the profit mechanism of farmers and disease transmission mechanism in order to design a more effective and reasonable control strategy to maximize the profits of farmers. We propose a dynamic model combining the economic factors, behaviors of livestock farmers and transmission mechanism of brucellosis. Then we investigate the result of the optimal strategy in theory using Pontryagin Maximum Principle and its existence and uniqueness are proved. To verify the accuracy and applicability of the theory, the model are simulated by the least square method based on the price data and infected people data of Ningxia Hui Autonomous Region. The simulation results show that brucellosis is in an outbreak in Ningxia Hui Autonomous Region and the current control policy must be adjusted. Sensitivity analysis indicate economic factors have certain influence on the outbreak of diseases. Under different compositions of three control items (including reduce the contact between susceptible and infected animals, increase the vaccination of susceptible animals, and reduce the discharge of Brucella), we evaluate the optimal control strategy for Ningxia Hui Autonomous Region from profits and infected brucellosis livestock perspectives. The profit results show that the government should increase financial support for disease control and it is effective to implement control by stages.