title: Progress towards polio eradication, Somalia and southern Sudan. January 1998-June 1999.
mesh_terms: D006801:Humans; D017589:Immunization Programs; D011051:Poliomyelitis / Q000453:epidemiology / Q000517:prevention & control*; D012998:Somalia / Q000453:epidemiology; D013397:Sudan / Q000453:epidemiology