As in the Hepatitis E-only model, PottersWheel Toolbox is used to investigate the basic reproduction number R C , when natural mortality is not equal to zero, (i.e. mw0) A sequence of parameter estimates are generated, this time setting the fits in sequence to 20. The process is repeated until a set of 50 readings is obtained. The parameters are chosen in such a way that 0:1077vsv0:4777 (i.e. 15v1=sv64 days, the Hepatitis E incubation period, [26, 31, 32] ), and x 2 value is less than 65. The basic reproduction number for each run is calculated using the expression in equation (14) .