No country is safe without global eradication of poliomyelitis.

In 1988, the World Health Assembly endorsed the goal of eradicating poliomyelitis worldwide. At the time, the estimated annual number of new cases of paralysis was 350,000, and poliomyelitis was considered to be endemic in 125 countries.1 In the 25 years since then, the incidence of poliomyelitis has been reduced by more than 99%, and only three countries — Pakistan, Nigeria, and Afghanistan — have never terminated indigenous transmission.1,2 Wild-type poliovirus type 2 has probably been eradicated; the last naturally occurring case was detected in 1999.2 Wild-type poliovirus type 3 appears to be close to eradication, with no new cases detected in 2013 (as of October 31, 2013).3-5 However, wild-type poliovirus type 1 remains in circulation.2,3 As illustrated by the 2011 poliomyelitis outbreak in China — a country that had not reported a case of paralysis caused by wild-type polioviruses since 1994 — as long as polioviruses circulate anywhere in the world, they can be exported to countries that are now poliomyelitis-free and can cause serious outbreaks.6 Public health authorities in China are to be commended for containing the outbreak so quickly. As described by Luo et al.6 in this issue of the Journal, a mass campaign to inoculate children with trivalent oral poliovirus vaccine was started within 3 weeks of outbreak confirmation, and the last case was detected approximately 1 month after the campaign was initiated. However, to make sure that polioviruses were truly eliminated, a total of five mass campaigns were conducted, in which 43.7 million doses of oral poliovirus vaccine were administered.6 The cost of containing the outbreak was considerable. Approximately $26 million (in U.S. dollars) was allocated for outbreak control. This cost does not include the less tangible cost of diverting hundreds of public health experts and local health workers from other important public health work. The apparently high immunity levels in this area of China probably made containment easier, since the population immunity was already close to herd-immunity thresholds.6 Should a similar outbreak occur in a poorer country with lower routine immunization coverage, or in a country that is not capable of responding as quickly, containment could prove far more difficult, as may be the case in the current importation of the poliovirus to the Horn of Africa and the Middle East, including Syria. Underscoring the highly infectious nature of poliomyelitis, importation of polioviruses from reservoir countries into areas that had been free of wild-type poliovirus has occurred in at least six countries so far this year, including Somalia (which had been free of the wild-type poliovirus since 2007), Kenya, Ethiopia, Syria, Cameroon, and Israel.3,7 The outbreak in the Horn of Africa was genetically traced to viruses from Nigeria, whereas the widespread circulation of wild-type poliovirus type 1 in Israel was linked to virus originating in Pakistan.7,8 To end poliomyelitis forever, the Global Polio Eradication Initiative (GPEI) has developed a comprehensive strategic plan to interrupt all transmission of wild-type poliovirus by the end of 2014 and to certify the world as poliomyelitisfree by 2018.2 Global eradication will require several key actions; these include administering oral poliovirus vaccine to interrupt the transmission of wild-type polioviruses, building and sustaining political commitment, improving routine immunization delivery in remaining reservoir