Dynamic analysis of rabies transmission and elimination in mainland China

Abstract

Rabies is an acute zoonotic infectious disease caused by rabies virus. In 2015, the World Health Organization proposed the goal of eliminating dog-induced human rabies by 2030. In response to this goal positively, China has been dedicated to the control and elimination of rabies mainly caused by dogs, for nearly 10 years. By applying infectious disease dynamics, in this paper, we establish a dog-human rabies transmission model to forecast future epidemic trends of rabies, assess whether the goal of eliminating dog-induced human rabies cases in China can be achieved in 2030, and further evaluate and suggest the follow-up sustained preventive measures after the elimination of human rabies. By analyzing and simulating above dynamic model, it is concluded that rabies has been well controlled in China in recent years, but dog-induced human rabies cannot be eliminated by 2030 according to current situation. In addition, we propose to improve rabies control efforts by increasing the immunization coverage rate of rural domestic dogs, controlling the number of stray dogs and preventing the import of rabies virus in wild animals. Immunization coverage rate of rural domestic dogs which is currently less than 10% is far from requirement, and it needs to reach 50%-60% to meet the goal of 2030. Since it is difficult to immunize stray dogs, we suggest to control the number of stray dogs below 15.27 million to achieve the goal. If the goal of eliminating human rabies is reached in 2030, the essential immunization coverage needs to be maintained for 18 years to reduce the number of canine rabies cases to zero. Lastly, to prevent transmission of rabies virus from wild animals to dogs, the thresholds of the number of dogs and the immunization coverage rate of dogs after eliminating canine rabies cases are also discussed.

Keywords: Dog-induced rabies; Dynamics; Elimination; Reproduction number; Stray dog population; Vaccination.

Fig. 1

Dog-induced human rabies cases in China from 1996 to 2022. Dog-induced human rabies cases account for 95% of the total human cases.

Fig. 2

The flow chart of rabies transmission between dogs and humans.

Fig. 3

The fitting chart of dog-induced human rabies cases from 2015 to 2022. The red dots represent the data reported by the Chinese Center for Disease Control and Prevention while the solid curve represents the fitting result of model. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 4

The change of effective reproduction number with time. The blue line is the mean value, and the gray area is the 95% confidence interval for 100 random simulations. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 5

(a) Prediction of the total number of people in China. (b) Prediction of the number of dogs in China. (c) The ratio of people to dogs.

Fig. 6

The prevalence of rabies. (a) The number of human rabies cases. (b)The positive rate of canine rabies.

Fig. 7

(a) The relationship between immunization coverage rate of dogs and theoretical human cases number of model in 2030. Dots represent 100 times of predicted number of human rabies cases in 2030 with different immunization coverage rate. (b) The relationship between immunization coverage rate and canine cases in 2030. When immunization coverage rate is 47%, the theoretical number of canine cases in 2030 is in [1886, 2228].

Fig. 8

The relationship between the proportion of stray dogs and the theoretical number of human cases in 2030.

Fig. 9

R₀ in term of the number of stray dogs.

Fig. 10

The theoretical number of canine cases. The initial values of model variables are taken as follows. $S\left(0\right)=1.2922\times {10}^8,E\left(0\right)=1.9609\times {10}^3,I\left(0\right)=96.1098,R\left(0\right)=9.9276\times {10}^7,S_1\left(0\right)=1.4517\times {10}^9,$$E_1\left(0\right)=0.26,I_1\left(0\right)=1.1434,R_1\left(0\right)=8.5058\times {10}^6.$

Fig. 11

Dog immunization coverage in terms of number of dogs. The blue line is where $R_0=1$. Above the blue line is where $R_0<1$, and below the blue line is where $R_0>1$. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)