世界ポリオ根絶の失われた10年とポリオ根絶計画のこれから

Abstract

The Global Polio Eradication Initiative was aimed to eradicate poliomyelitis by the year 2000, however, polio eradication is still not in sight even in 2010, over 10 years after the initial target date. In 2010, indigenous transmission of wild polioviruses has been interrupted throughout the world except four countries, Afghanistan, Pakistan, India, and Nigeria. Despite the intense use of monovalent oral polio vaccines, type 1 and type 3 wild polioviruses still circulate in the four remaining polio-endemic countries, and multiple importations of wild polioviruses have also occurred extensively from Nigeria and India to a number of previously polio-free countries in Africa, Asia, and Europe. Furthermore, the emergence of type 2 vaccine-derived polioviruses has raised concerns about low level of immunity against type 2 poliovirus in some polio-endemic areas like Nigeria and India. On the other hand, operational improvements in 2009 were reported in high-risk states in northern Nigeria and transmission of type 1 and type 3 polioviruses in Nigeria is markedly declining from 2009 to 2010. Moreover, bivalent oral polio vaccine containing Sabin 1 and Sabin 3 strains has been introduced in 2010 as a promising tool to improve and simplify the supplemental immunization activities in high-risk areas. Although there was no apparent decline in the annual number of polio cases in 2000-2009 globally, it would be critical to review our experience during "the lost decade of global polio eradication" to move forward into the final stage of global polio eradication.