Polio: worldwide eradication progress
Wildtype polio is still considered to be endemic in 3 countries. Cases are still occurring in Pakistan and Afghanistan as of April 2019. The last case in Nigeria occurred in 2016. Wildtype polio has been eradicated from the Western Hemisphere and most of the rest of the world.
Outbreaks of cVDPV are occurring sporadically in parts of Africa, the Middle East, and S.E. Asia where OPV is used exclusively. Virulence conversion has occurred with types 1, 2, or 3 in various locations; these strains are designated by type number, e.g., "cVDPV1"
