With clustering, the HIV incidence due to IDU and sexual intercourse were mostly identical in the 1994Á1999 and 2000Á 2004 periods. However, three spatial clusters of sexually acquired HIV emerged in the 2005Á2009 period (RR 0 3.44, p 0 0.0005; RR 0 10.60, p0 0.011; RR 0 2.18, p 0 0.0265), which did not correspond to an increased RR of IDU-acquired HIV (see Fig. 1 ). Proportion of Radas, simultaneously included in the clusters of both types of HIV transmission, decreased from 64.58% in 2000Á2004 to 48.33% in 2005Á2009.