Battling bird flu by the numbers

Los Alamos mathematical model gauges epidemic potential of emerging diseases

LOS ALAMOS, New Mexico, May 27, 2008—A pair of Los Alamos National Laboratory theorists have developed a mathematical tool that could help health experts and crisis managers determine in real time whether an emerging infectious disease such as avian influenza H5N1 is poised to spread globally.

In a paper published recently in the Public Library of Science, researchers Luís Bettencourt and Ruy Ribeiro of Los Alamos’ Theoretical Division describe a novel approach to reading subtle changes in epidemiological data to gain insight into whether something like the H5N1 strain of avian influenza—commonly known these days as the “Bird Flu”—has gained the ability to touch off a deadly global pandemic.

“What we wanted to create was a mathematically rigorous way to account for changes in transmissibility,” said Bettencourt. “We now have a tool that will tell us in the very short term what is happening based on anomaly detection. What this method won’t tell you is what’s going to happen five years from now.”

Bettencourt and Ribeiro began their work nearly three years ago, at a time when the world was wondering whether avian influenza H5N1, with its relatively high human mortality rate, could become a frightening new pandemic. Health experts believe that right now the virus primarily infects humans who come in contact with infected poultry.

But some health experts fear the virus could evolve to a form that would become transmissible from human to human, the basis of a pandemic like the 1918 Spanish Flu that killed an estimated 50 million people.

The Los Alamos researchers set out to create a “smart methodology” to look at changes in disease transmissibility that did not require mounds of epidemiological surveillance data for accuracy. The ability to look at small disease populations in real time could allow responders and health experts to implement quarantine policies and provide medical resources to key areas early on in an emerging pandemic and possibly stem the spread.