The complete system in the original variables ͑see p. 2͒ will evolve in time t in the following way: transition rate ͑s − 1,e + 1,i͒ ␤si/N ͑s,e − 1,i + 1͒ ␣e ͑s,e,i − 1͒ ␥i ͑s + 1,e,i͒ N ͑s − 1,e,i͒ s ͑s,e − 1,i͒ e ͑s,e,i − 1͒ i.