LETTER FROM CAMEROON THE DOOMSDAY STRAIN Can Nathan Wolfe thwart the next Alps before it spreads? BY MICHAFI. SPECTER aT ook up," Nathan Wolfe barked. Li I didn't respond immediately, so the next suggestion came with an el- bow to the ribs: "Take your head out of that map." We were standing on the side of "the road," a dirt highway that passes through the center of Min- dourou, a dusty logging village in southeastern Cameroon. Wolfe, the director of Global Viral Forecasting, and several colleagues were in the midst of a ten-hour drive from the cap- ital, Yaounde, to a town called Ngoila, one of the many sites that G.V.F. has established in the past decade to mon- itor the emergence of deadly viruses from the jungles of Central Africa. He nodded toward a couple who had just pulled up beside us on a Chinese mo- torcycle. The driver wore flip-flops and a red tracksuit. His passenger, dressed in a pale-blue shirt and a matching pill- box hat, looked as if she were on her way to church. But that wasn't where they were headed. Her right arm was wrapped around the driver's waist. In her left, she clutched the lengthy tail of a freshly trilled agile mangabey, a mon- key often found in the lush forests of the region. "Those monkeys are viral ware- houses," Wolfe said to me, as the cou- ple drove toward the market, drag- ging their bloody merchandise behind them. Mangabeys carry many viruses that infect humans, including one that may cause a rare form of T-cell leuke- mia and another, simian foamy virus, the ultimate impact of which is not yet known. Wolfe is a forty-year-old biol- ogist from Stanford University: a swar- thy man with a studiously dishevelled look, he comes off as a cross between a pirate and a graduate student. He is also the world's most prominent virus hunter, and he spends much of his time sifting through the blood of wild ani- mals. "When I see a monkey like that dragged through the street, bloody, on the way to mark