A few weeks ago, I wrote a post examining where Wikipedia edits come from. The map below drills into the data in slightly more detail in order to visualise where edits in Africa come from (the data include edits to all language versions of Wikipedia).
The number of Internet users in a country explains some of the patterns that we see here, but can't in any way explain all of the variance in the map (e.g. take a look at Nigeria - a country with over 45 million Internet users).
My team and I are currently working on a paper in which we use a range of secondary data to further examine these inequalities in participation in East Africa and the Middle East and North Africa. I'll share a draft as soon as possible.