Smith? et al. [15] examined a metapopulation model with travel between two regions, with reproductive ratios R (0) 0,1 and R (0) 0,2 for each region in the absence of travel, and R 0,1 and R 0,2 when only susceptibles travel, but infectives do not. They showed that if both R (0) 0,1 < 1 and R (0) 0,2 < 1, then there are conditions on the travel of susceptible such that R 0,1 > 1 and R 0,2 < 1. Thus, a disease which would otherwise be eradicated in both regions could be sustained in one of the regions if there were sufficient travel of the susceptibles (not infectives). Furthermore, if R (0) 0,1 < 1 and R (0) 0,2 > 1, then there are conditions on the travel of susceptibles such that R 0,1 > 1 and R 0,2 > 1. Thus, if one region sustains the disease on its own, while the other does not, then sufficient travel of susceptibles (not infectives) could sustain the disease in both regions.