The Lancet  
Sep 28, 2013  Volume 382  Number 9898  p1071 – 1152  e6 – 9
http://www.thelancet.com/journals/lancet/issue/current

Letter
Poliomyelitis: threats to eradication
Mohammed Umer Mir, Mehreen Bhamani

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The recent isolation of wild poliovirus from Israeli sewage samples1 (environmental sampling) elucidates an important consideration for polio eradication. The Iocal population has humoral immunity against the poliovirus because of high rates of coverage with inactivated polio vaccine (IPV).2 But not everyone has mucosal (intestinal) immunity because of removal of oral polio vaccine (OPV) from routine immunisation since 2005, and absence of endemic wild poliovirus conferring natural immunity. People immunised with IPV are protected from disease but the poliovirus replicates in their intestines and is shed with stools for about 3 weeks after initial infection.