Since the first cases of HIV/AIDS disease were recognised in the early 1980s, a large number of mathematical models have been proposed. However, the mobility of people, which has an obvious impact on the spread of the disease, has not been much considered in the modelling studies. This book provides various new results pertaining to the spread of the disease, including epidemic intervention, in mobile populations. The results can serve as a basic framework how to formulate and analyse a more realistic stochastic model for the spread of HIV in mobile heterogeneous populations - classifying all individuals by age, risk, and at the same time considering different modes of the disease transmission. Some strategies such as how to allocate a limited budget to minimise the number of new HIV cases over a finite time horizon as people move among regions might provide some useful information in controlling the spread of the disease. A novel approach using the Cross-Entropy (CE) method is introduced to solve such highly non-linear and multidimensional problems. This book, therefore, should be especially useful to those interested in Epidemic Modelling, Analysis, and Simulation fields.