There are just three countries in the world where polio is still endemic: Afghanistan, Pakistan, and Nigeria. Now, experts think it's feasible for Nigeria to wipe out wild poliovirus within its borders this year, even as the country stays on high alert against Ebola. If Nigeria does eradicate wild polio, it would be a big help to the rest of the world. Since 2003, polio has migrated from Nigeria to 31 polio-free countries.
(Those countries were able to control the outbreaks.) But Nigeria hasn't seen a single case of wild polio transmission since July. The country has had 21 cases of polio arising from vaccination in 2014, which happens in areas where some people are vaccinated, but many people are not, and sanitary conditions are poor. (The version of the polio vaccine that high-income countries use, including the U.S., does not give rise to circulating vaccine-derived polio.) Experts…
