Yes, but they have only made a debut in the Gakuen Hetalia game.They have yet to make an appearance in the actual manga.
In addition, one might remember that both Egypt and Seychelles are African countries (featured in the manga (both), Egypt in the anime)~ Cameroon is also an African country, designed primarily for the World Cup South Africa 2010 group pictures.
As for the African class in Gakuen Hetalia, the only full-body designs appear to be for Kenya, Zimbabwe, and another female nation.
Full credits are here--http://hetalia.wikia.com/wiki/Gakuen_Hetalia Located at the very bottom:
Kenya (seen as a chibi head): Introduced as a British territory. Her favorite food is nyama choma. Uganda (chibi head): Introduced as a British territory. They state that they took their name from the former Kingdom of Buganda. Zimbabwe (chibi head): Introduced as a British territory. Botswana (chibi head): Introduced as a British territory. They like to weave baskets and bead things, and believe that they can cook seswaa the best. Ghana (chibi head): Introduced as a British territory. Cabinda: Introduced as a Portuguese territory. Guinea-Bissau: Introduced as a Portuguese territory. Congo: Introduced as a Belgian territory. Sahara: Introduced as a Spanish territory. Ethiopia: Introduced as an Italian territory. He is made fun of by the rest of the class for being this, and is nervous to admit to it.
It also mentions the possibly of a Libya character, although there is no known design of him/her.
Original sourcing was from this post (http://community.livejournal.com/hetalia/2753593.html), although I feel tdei makes an interesting observation over the validity of the screenshots (http://tdei.livejournal.com/434324.html). We shall just have to see, I suppose <3