Rollins, James, 1961- Sigma Force novel

Series name and numeration from Amazon.com

"It begins in Africa... A United Nations relief team in a small village in the Congo makes an alarming discovery. Men, women, and children have been reduced to a dull, catatonic state. The environment surrounding them--including plants and animals--has grown more cunning and predatory, evolving at an exponential pace. The insidious phenomenon is spreading from a cursed site in the jungle--known to locals as the Kingdom of Bones --and sweeping across Africa, threatening the rest of the world. What has made the biosphere run amok? Commander Gray Pierce and Sigma Force have kept the world safe. Yet, even these seasoned scientific warriors do not understand what is behind this frightening development--or know how to stop it. As they race to find answers, the members of Sigma quickly realize they have become the prey. Sigma Force must risk their lives to uncover the shattering secret at the heart of the African continent--a truth that will illuminate who we are as a species and where we may be headed...sooner than we know. Mother Nature--red in tooth and claw--is turning against humankind, propelling the entire world into the Kingdom of Bones." -- Back cover