Figure 10.

The Wu Model [10] (a SEIR model) with 4 variables: the number of susceptible S, latent E, infectious I, and removed R individuals, and only one organization: $\{\text{S},\text{E},\text{I}.\text{R}\}$, that contains all species. Thus this model implicitly assumes the infection to persist forever once it occurs which is a totally contrary assumption compared to the models assuming the vanishing of infection in the like the previously analyzed Nesteruk model. The signature of this model is: $\underset{\_}{\text{X}}\underset{\_}{\mathrm{X}}$.