It is to be mentioned here that distinguising between infected and uninfected compartments cannot be
done only from the structure of the equations but depends also on the epidemiological interpretation of
the model. Also, the basic reproductive ratio does not depend on the structure of the model (system
of ODE) alone but also on the definition of the infected and uninfected compartments.
Now, we consider the following system of equations for the disease transmission model (epidemic model)