White devils / Paul McAuley.

Enhanced descriptions from Syndetics:

One of the most exciting new science fiction writers of the new millennium, Paul McAuley has already won the Arthur C. Clarke Award, the Philip K. Dick Award, and the John W. Campbell Award. Now he presents a disturbingly convincing exploration of the future of Africa, the darker applications of biotechnology, and of the very nature of the human psyche.
The Congo, roughly thirty years from now. Plague, civil war, and rampant genetic engineering have spawned widespread chaos and devastation throughout Africa. Nicholas Hyde is investigating a reported massacre in a remote corner of the Congo when his team is attacked by a band of fierce apelike creatures, possibly the result of illegal genetic experimentation on chimpanzees. Nick survives the encounter, only to discover himself at the center of a massive cover-up.
Obligate, the supposedly eco-friendly transnational that now controls the Congo, denies the existence of the "white devils," and will stop at nothing to suppress all evidence to the contrary. Although Nick has secrets of his own to conceal, he becomes determined to uncover the origin of the mysterious creatures---and why certain individuals will kill to bury the truth.
But even the atrocities he has already witnessed cannot prepare him for the terrifying secret of the white devils.