Figure 6.31 Communicable disease diffusion in Iceland. Hypothetical sketch of the spread of an infectious disease agent from an international source down to a farm family in rural Iceland. The arrows indicate possible contacts. At levels 1 and 2, the movements are likely to be young adults; at 3 and 4, children. The synchrony of Iceland with Europe and the United States as international sources which seed infectious diseases in Iceland is discussed in Weinberger, et al. (2012).