The slippery geographies of polio

The 2013 deadline for the worldwide goal to eradicate polio has come and gone, with a new endgame set for 2018. Although cases of polio have decreased by 99% worldwide since 1988, geopolitical conflicts have exacerbated its spread—Syria, Ethiopia, and Kenya have reported polio infections, and Afghanistan, Nigeria, and Pakistan remain endemic. The virus has resurfaced in Israel, and might be linked to use of intravenous inactivated polio vaccine (IPV). Transnational mobility also contributes to polio\'s persistence, and circulating vaccine-derived poliovirus (cVDPV) in Yemen, Mozambique, and Madagascar is further complicating eradication efforts.6