THE BASIC REPRODUCTION RATIO OF HIV AMONG INTRAVENOUS-DRUG-USERS

A new approach for the estimation of the Basic Reproduction Ratio Ro f or HIV among intravenous drug users (IVDU) is proposed. This approach is based in an adaptation of the models proposed by Ross and Macdonald for vector-borne infections. A straightforward adaptation of Macdonal d's model is presented first: biological vectors are replaced by needl es and syringes and we consider a homogeneous population of IVDUs; nex t we present a modified model where several heterogeneities are consid ered. Some of those heterogeneities are due to intrinsic differences b etween needles and syringes and biological vectors; others, such as th ose related to movements of individuals between communities, should ap ply to both biological vectors and injection apparatuses. An example o f the calculations of R(0) for a real IVDUs community is presented.