Robert Ludlum's The Ares Decision

When a U.S. Special Forces team is wiped out by a group of normally peaceful farmers in Uganda, Covert-One operative Jon Smith is sent to investigate. Video of the attack shows even women and children possessing almost supernatural speed and strength, consumed with a rage that makes them immune to pain, fear, and all but the most devastating injuries. Smith finds evidence of a parasitic infection that for centuries has been causing violent insanity and then going dormant. This time, though, it's different. And as Smith and his team are cut off from all outside support, they begin to suspect that forces much closer to home are in play...