I think there's a bit more to it than just poverty but poverty and education are definitely huge issues. There are also many cultural and traditional practices which have assisted the spread of the disease as well.
A couple of links to some of the factors that have made the spread of AIDS in Africa so much more than in other regions of the world. The 1st one is a bit dated but from the 2nd article almost 20 years later it appears the same issues are persisting.
Cultural practices contributing to the transmission of HIV in Africa
http://www.nytimes.com/2006/11/21/wo...1cameroon.html