A Nigerian health commissioner Dr. Sani Malam vaccinates a child for polio during a national immunization drive in Bauchi, Nigeria, last week. Deji Yake/EPA /Landov hide caption

itoggle caption Deji Yake/EPA /Landov

A boy works at an illegal gold mine in northern Nigeria. Lead from these mines has sickened thousands of children in the region. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

Ado Ibrahim carries his son Aminu through a village in northern Nigeria. Aminu, 4, was paralyzed by polio in August. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

Sahya Idriss, a service provider at the health clinic in Minjibir, carries a vial of the polio vaccine. David Gilkey/NPR hide caption

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Women and their children wait for medication and instructions on how to use it at the clinic in Dareta, Nigeria. Treating children with high levels of lead is a painstaking process that works only if their environment at home is free from lead. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

A young boy works at an illegal gold mine in Dareta, Nigeria. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

Women and their children wait for medication and instructions on how to use it at the clinic in Dareta, Nigeria. Treating children with high levels of lead is a painstaking process that works only if their environment at home is free from lead. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

A picture taken with a photo camera shows residents of the Iju district of Lagos, Nigeria, gathering at the site where a Dana Air jet crashed into a neighborhood on Sunday. AFP/Getty Images hide caption

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Onlookers view the wreckage of a car bomb that exploded outside a church near Madalla, Nigeria on Christmas Day, 2011 killing scores of people. Boko Haram claimed responsibility for the attack. Sunday Aghaeze/AP hide caption

itoggle caption Sunday Aghaeze/AP