While the metapopulation framework highlights the role of migration in maintaining regional persistence, the inherent challenges in measuring human movement have limited the ability to predict the specific dynamics of large-scale disease metapopulations (though see Grenfell 2001 Xia 2004 for a comprehensive retrospective analysis of the very regular patterns of measles fade-out in England and Wales in the pre-vaccine era). Increasingly, remote sensing technology, such as satellite imagery and cell phones, have allowed formal quantification of rates of human movement between population centers, from which we can characterize the dynamics of connectivity may allow a more operational understanding of epidemic sources and sinks from which we can more effectively prioritize surveillance and control efforts Bharti 2016.