Abstract
Under the current International Health Regulations, 194 states parties are obligated to report potential public health emergencies of international concern to the World Health Organization (WHO) within 72 hours of becoming aware of an event. During July 2007-December 2011, WHO assessed and posted on a secure web portal 222 events from 105 states parties, including 24 events from the United States. Twelve US events involved human influenza caused by a new virus subtype, including the first report of influenza A(H1N1)pdm09 virus, which constitutes the only public health emergency of international concern determined by the WHO director-general to date. Additional US events involved 5 Salmonella spp. outbreaks, botulism, Escherichia coli O157:H7 infections, Guillain-Barré syndrome, contaminated heparin, Lassa fever, an oil spill, and typhoid fever. Rapid information exchange among WHO and member states facilitated by the International Health Regulations leads to better situation awareness of emerging threats and enables a more coordinated and transparent global response.