The surveillance challenge: final stages of eradication of poliomyelitis in the Americas.

Current levels of surveillance have contributed to substantial reductions in morbidity and mortality due to poliomyelitis in the Americas. Despite the success of the poliomyelitis eradication initiative, it has become critical that surveillance be intensified so that the absence of wild poliovirus circulation can be verified with confidence in countries not reporting confirmed cases of poliomyelitis. Cases of acute flaccid paralysis continue to be classified as compatible with poliomyelitis, because investigations of such patients do not provide sufficient information to rule out wild poliovirus as the cause of paralysis. At this stage of the eradication initiative, the presence of compatible cases in some countries in Latin America indicates a failure of the surveillance system. The greatest challenge for the eradication initiative may be correcting the remaining deficiencies of the existing surveillance system that hinder efforts to verify that wild poliovirus is no longer being transmitted in the Americas.