On May 5, 2014, the World Health Organization (WHO) Director-General declared the international spread of wild poliovirus a Public Health Emergency of International Concern. At end-2013, 60% of polio cases were the result of international spread of wild poliovirus, and there was increasing evidence that adult travellers contributed to this spread.

The current situation stands in stark contrast to the near-cessation of international spread of wild poliovirus from January 2012 through the 2013 low transmission season for this disease (i.e. January to April). If unchecked, this situation could result in failure to eradicate globally one of the world’s most serious vaccine preventable diseases.