News Feature: Special agents offer modeling upgrade.

When news of West Africa’s Ebola outbreak first appeared in the spring of 2014, “the world wasn’t paying a lot of attention,” says Bryan Lewis. After all, previous flare-ups of the virus had burned out quickly, mainly because victims tend to die of fever, shock, and spontaneous bleeding before they can spread the virus very far. Except this time was different. In the hardest hit nations of Guinea, Liberia, and Sierra Leone, the Ebola toll just kept climbing. By early summer, the region was seeing about 100 new cases every week, and alarm bells were going off in public health organizations around the world. So in July, Lewis wasn’t too surprised when the United States government’s Defense Threat Reduction Agency (DTRA) asked him to develop a model of how the outbreak might progress. “I didn’t even hesitate,” says Lewis, a computational biologist at the Virginia Polytechnic Institute and State University (Virginia Tech) in Blacksburg. He and his Virginia Tech colleagues had spent a decade building sophisticated computer simulations of how people and pathogens behave during epidemics, but this was a rare chance to help save people in real time. “It fired up my public health juices,” he says. It was the beginning of a 7-month sprint. Lewis and his colleagues found themselves working in tandem with modeling teams around the world (1), all feverishly racing to answer relief agencies’ questions fast enough tomake a difference on the ground: Howbadwill it get? How many mobile hospitals should we send? And how do we field-test a vaccine?