It depends on where in Africa we're talking about.

Generally, "Old World" epidemic diseases did not have the same effect on populations in northern and eastern Africa as they did in other parts of the continent. Historically, there has been a good deal of contact between these regions and other parts of Eurasia, so many populations could develop limited immunity to diseases like smallpox and measles.

There are examples, however, of epidemic diseases wreaking havoc on communities in sub-Saharan Africa, both indigenous and settler population alike. I know, for example, there was a smallpox epidemic in Cape Town in 1713 that was very damaging to the Khoisan people, and I'm sure there are other epidemic events like it (similar outbreaks occurred in 1755 and 1767). African history isn't my forte, so I'm hoping that someone else can step in and provide detailed information.