We assume that the case-counts in the regions follow independent ZIP random variables with the same probability p of a structural zero. The ZIP model allows for additional flexibility when compared to the Poisson. When structural zeros occur, the ZIP model accounts, in average, for a reduction in the casecounts. The ZIP model allows for superdispersion or extra-Poisson variation, while the Poisson model often understimates the observed dispersion. Regarding the likelihood ratio test formulation for the ZIP model we describe our Scan-ZIP statistic considering (a) we know when a zero count is a structural one and (b) we do not know, for sure, whether or not a zero count is a structural one. For the latter case, the Scan-ZIP statistic is obtained through an EM procedure.