Progress toward poliomyelitis eradication--Afghanistan and Pakistan, January 2002-May 2003.

Since 1988, when the World Health Assembly resolved to eradicate poliomyelitis worldwide, the number of countries in which polio is endemic has decreased from 127 to seven, including Afghanistan and Pakistan. These two countries are considered one epidemiologic block because of their geographic proximity, frequent cross-border population movement, and the presence of genetically similar wild poliovirus (WPV) lineages. Although polio remains endemic in both countries, progress in interrupting poliovirus transmission has been substantial. This report describes intensified polio eradication activities in Afghanistan and Pakistan during January 2002-May 2003, summarizes progress made, and highlights the remaining challenges to interrupting poliovirus transmission.