Reconsideration of the plague transmission in perspective of multi-host zoonotic disease model with interspecific interaction

The human-animal interface plays a vital role in the spread of zoonotic diseases, such as plague, which led to the "Black Death", the most serious human disaster in medieval Europe. It is reported that more than 200 mammalian species including human beings are naturally infected with plague. Different species acting as different roles construct the transmission net for Yersinia pestis (plague pathogen), in which rodents are the main natural reservoirs. In previous studies, it focused on individual infection of human or animal, rather than cross-species infection. It is worth noting that rodent competition and human-rodent commensalism are rarely considered in the spread of plague. In order to describe it in more detail, we establish a new multi-host mathematical model to reflect the transmission dynamics of plague with wild rodents, commensal rodents and human beings, in which the roles of different species will no longer be at the same level. Mathematical models in epidemiology can clarify the interaction mechanism between plague hosts and provide a method to reflect the dynamic process of plague transmission more quickly and easily. According to our plague model, we redefine the environmental capacity K with interspecific interaction and obtain the reproduction number of zoonotic diseases R-Z(0), which is an important threshold value to determine the zoonotic disease to break out or not. At the same time, we analyze the biological implications of zoonotic model, and then study some biological hypotheses that had never been proposed or verified before.