Urban Refugees in Nairobi, Kenya.

NAIROBI, KENYA - MAY 7, 2013: A single refugee woman and her seven children share a plate of rice for lunch. Food security is a daily challenge for urban refugees and many children suffer from malnutrition. Humanitarian organizations wrestle with how best to distribute aid to the most vulnerable when their circumstances require children to remain hidden for their safety. Half of Africa's 2.5 million refugees now live in cities - marking a major migration shift from camps to urban centers. Living in the shadows of Africa's slums are the newest faces of the world's changing refugee crisis: urban and alone. (Photo by Amy Toensing/Corbis via Getty Images)