Previous studies suggest that data on air travel can be used to predict the spread of newly emerged human pathogens and better target public health measures [15, 16, 17, 18] . Our analyses support this, but demonstrate that the ability of a country to rapidly detect, diagnose, and report the new infection is a critical element that enhances our predictive power and control capacity. Other studies suggest that analysis of the underlying drivers of disease emergence (e.g. agricultural intensification, land-use change) can be used to predict the geographic origins of new emerging diseases [2] . The currently circulating pandemic influenza strain is a triple reassortment virus with closest known relatives from Europe, Asia, and North America, but there is uncertainty regarding its origin due to the large temporal separation between this pandemic 2009 A/H1N1 strain and the nearest ancestors (10-15 years) [7] . Our analyses of swine and poultry trade demonstrate an enormous potential for intercontinental mixing of potentially zoonotic pathogens, including influenza A viruses. Although artificial insemination is the predominant strategy for interbreeding of commercial swine, live swine are still routinely traded for breeding purposes [19] . Large numbers of poultry are also traded globally, and low pathogenicity influenza viruses are likely to spread unnoticed among poultry until they reassort or mutate to highly pathogenic forms, such as the A/H1N1v strain. This strain notably was the results of reassortment of several relatively low pathogenic influenza strains, as explained by Garten et al. [8] . In addition, as the recent cases of workers exposing a herd of pigs to the 2009 A/H1N1 virus makes clear [20, 21] , even dramatic reductions in the international live animal trade may not prevent the exposure of local livestock to novel viral types from distant locations [9, 10] . Although extensive trade of poultry and swine between continents and within the North American countries almost certainly contributed to the emergence of this virus, surveillance of influenza strains circulating among traded animals is poor [10] , so that it is impossible to designate any single country, trade connection or market as the key point at which the new strain evolved. Expanded surveillance for influenza in livestock populations may allow more of the markers of transmissibility and virulence to be identified, or factors driving higher virus transmission to be determined [9, 22] . In particular, we need to analyze all influenza strains, including the non-and low pathogenic influenzas, in addition to the highly pathogenic ones, with greater regularity. Only by this thorough surveillance can we begin to understand what differentiates the strains that cause pathogenesis in humans from those that do not. Such that eventually we may be able to predict viral emergence and develop vaccines against pandemic influenza viruses in advance of their spread. In order to develop such capability, we need to do more surveillance of livestock and wild influenza strains now.