Fig. 6

Trends of the basic reproduction number \(R_{0}\) varying with in parameters \(c_{hh}\), \(c_{lh}\) and \(\beta_{h}\). a Impact of parameters \(c_{hh}\) and \(\beta_{h}\) on the basic reproduction number \(R_{0}\). b Impact of parameters \(c_{lh}\) and \(\beta_{h}\) on the basic reproduction number \(R_{0}\). The right-side legend corresponds to the values of \(R_{0}\), and the black solid line represents \(R_{0} = 1\)