Figure 1.

Depiction of the Markov chain of the (a) birth–death process with state definition {B} where B∈ℕ is the number of bacteria, and (b) birth–death–survival process with, as an example, G = 3 and state definition {T,P} where T∈ℕ is the total number of extracellular bacteria, B∈ℕ, and bacteria-containing phagocytes, P∈ℕ. The birth, death and survival rates are λ > 0 and μ > 0 and α > 0 respectively and the threshold for illness is M∈ℕ.