The latest data (2015) from the UNESCO Institute for Statistics (UIS) Adult and Youth Literacy: National, regional and global trends, 1985-2015 show that Sub-Saharan Africa (SSA) is home to over 191 million adults (15 years and above) who lack basic literacy skills, including 47 million youth (15–24 years). Nearly 50% (89 million) of illiterate adults and 50% (23 million) of illiterate youth live in just four countries: Nigeria, Ethiopia, Democratic Republic of Congo, and Tanzania. Nigeria and Ethiopia alone account for 37% (69 million) of adults and 37% (17 million) of youth who lack basic literacy in SSA. SSA also lags behind other regions in key indicators pertaining to quality and equity. Disparities in terms of gender, location and income have been endemic, deep and persistent, with the poor, girls, women and those in remote rural areas being disproportionately disadvantaged. 

SSA has one-seventh of the population worldwide. Yet it accounts for nearly half of all illiterate youth and more than a quarter of illiterate adults worldwide. The other region where youth and adult illiteracy is a huge challenge is South and West Asia. However, the two regions are poles apart in terms of the progress made during the Millennium Development Goals period. South and West Asia reduced its illiterate adult population by 19 million and its illiterate youth by 50 million from 1990 to 2015.  In Sub-Sahara Africa the number of adults and youth classified as illiterate increased by 58 million and 13 million respectively during the same period. Sub-Saharan Africa had been the only region saddled with this this peculiar affliction.

The economic and social cost of illiteracy is huge, corrosive, and immensely debilitating. Its destructive impacts are wide and far-reaching, cutting across all critical sectors of development.

Economic and Social Cost of Illiteracy
Economic	Lost earnings and limited employability
	Lost business productivity
	Lost wealth creation opportunities
	Lower technology skills capacity
Social	Poor health, poor quality of life & rising health costs
	Crime, including massive upshot in juvenile delinquency
	Increased & disabling dependency on welfare & charity
	Rapid increase of out-of-school children, drop-outs, gender-based inequality
Source: World Literacy Foundation (2015)

Two more recent, ominous and heavily consequential afflictions could also be linked to the high cost of illiteracy: youth radicalization and extremism and the tragic specter of African youth heading to Europe in droves, putting their safety and life in great danger in the perilous journey across the Sahara or in the treacherous waters of the Mediterranean Sea.

The World Literacy Foundation (WLF) estimates the cost of illiteracy to the global economy at $1.2 trillion. At the national level, aggregate figures vary greatly, depending on a wide range of factors. A developing country on average looses 0.5% of its GDP yearly due to illiteracy. This will translate to the following estimated annual losses for Angola ($500 million), Sudan ($381 million), Tanzania ($250 million), and Ethiopia ($288 million). Data is not available for Nigeria and D R of Congo. The WLF underscores that these estimates are quite conservative, and the actual cost of illiteracy is likely to be much higher.