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

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 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