As of May 8 th 2009, only two weeks after it was first reported, the 2009 A/H1N1 influenza strain had spread to 24 countries, 40 U.S. states (plus the District of Columbia) in the US, and 9 provinces in Canada ( Figure 1 ). This rapid spread resulted, in part, from the tight connectivity of the globe through air travel ( Figure 2) .