I doubt that it has anything to do with the fact that we changed how we are measuring unemployment in the US -- accounting for up to 5 years' unemployment at a stretch instead of only 2. So now people who were listed as 2+ years can be listed as 3. That doesn't change how many are unemployed, only our understanding of unemployment dynamics.
Aid Thoughts discusses the problems of using the same notion of unemployment in Sub-Saharan Africa that we use in the US:
Firstly, the condition of ‘being without work’ discriminates against women who are involved in economically productive activities. ... Women in Africa are very likely to combine economic activities with ‘non-economic’, household activities, and thus work intermittently over the year, or to work from home in either own-account or waged occupations – massively increasing the likelihood of being under-represented as employed labour. What’s more, in many countries, economically productive activities conducted by women (which may be crucial inputs to smallholder agriculture or home-based goods production) are classed as ‘housework’ and not an input into production. Men carrying out separate parts of the same production process are counted as working, self-employed. Another, equally large problem with the idea of unemployment exists in much of Sub-Saharan Africa: the condition of being completely without work hardly ever exists for people of working age without disability.