Figure 4

Time domain behaviors of SDDEs model (2) (right) and corresponding deterministic model (1) (left) when \({\mathcal{R}}_{0}^{s}=0.38<1\), with \(\eta =0.0005\), \(\xi =0.6\), \(\beta =0.01\), \(\sigma =0.12\), \(\alpha =0.3\), \(\gamma =0.02\); \(\tau =2.5\) and white noises \(\nu _{1}=0.02\), \(\nu _{2}=0.2\), \(\nu _{3}=0.02\), \(\nu _{4}=0.2\). The figure shows a periodic outbreak due to the time-delay τ