Why does Richard Preston both end and begin the book in Africa?

In beginning and ending his book in Africa, Preston comes full circle. In the novel's final section, the reader is introduced to Richard Preston as a character on his own journey through the world of the filoviruses. While Preston has been largely limited to third person narrative up to this point, he now provides the reader with his own perspective of Kitum Cave, as well as background about his time in Africa as a child. As a result, this section serves as a sort of nonfiction epilogue to the rest of the narrative. As the bulk of the story has already been told, Preston uses this opportunity to offer his own conclusions about the filoviruses and their role in the natural order.