Global dynamics of a periodic brucellosis model with time delay and environmental factors

Abstract

In China, brucellosis has always been a significant public health issue, especially in the pastoral regions of northern provinces where animal husbandry is well-developed. However, the impact of control measures, breeding characteristics and temperature fluctuations on the transmission dynamics of brucellosis outbreaks remains unclear. We construct a periodic mechanism-driven dynamic model with latent delay coupled with the regional breeding and temperature characteristics of Xinjiang Region. Theoretically, the global dynamics of periodic solutions are demonstrated by the theory of monotone dynamical system. In the application, the monthly human brucellosis cases and average temperature data of Xinjiang from 2015 to 2020 are fitted, and the basic reproduction number of brucellosis transmission is evaluated as 0.6691. Nonetheless, it is yet unable to attain the national control standards in the short term. The findings suggest that: 1. Interactions of periodic fluctuations in Brucella survival time and sheep shearing are key factors leading to the periodic outbreaks of brucellosis. 2. Improving the frequency of environmental disinfection could quickly eliminate the brucellosis epidemic. Specifically, when the disinfection frequency was once a month, the national control standard could be reached 5 years ahead of schedule. 3. In extreme cases, when the immunization rate κ=0 or the detection rate γ=0, the basic reproduction number might still be less than 1. From an epidemiological perspective, non-immunization control measures may be implemented with the reduction of brucellosis cases. The aforementioned statement may also bear resemblance to the preventive and control measures implemented in our country.