A computer model of the spread of hepatitis C virus among injecting drug users

A number of behavioural and clinical parameters influence the transmission of an infectious agent through direct contact between two individuals. The behavioural parameters encountered in such situations are also likely to ex hibit an enormous amount of variability. With the spread of hepatitis C amo ng injecting drug users, the parameters associated with injecting behaviour play an important role in the modelling of the transmission process. Compu ter simulation modelling is an ideal approach to deal with a large number o f parameters as well as high levels of variability without excessive simpli fication. The simulation model presented in this paper is tested on data fr om a cohort of injecting drug users and the results obtained are very encou raging from a public health perspective. The model clearly indicates that t he rate at which HCV spreads through a population of injecting drug users i s extremely sensitive to the interaction rate and to the probability of inf ection through a single contact with an infective. At the same time it show s that rate of spread is not very sensitive to initial prevalence, which is very encouraging from a public health perspective.