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Vol. LVII, No. 17
August 26, 2005

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Researchers Model Avian Flu Outbreak, Impact of Interventions

Two international research teams supported by NIGMS have developed computer models of what might happen if the deadly avian flu, found in birds throughout Southeast Asia, started passing efficiently between people. Could we stop an outbreak at its source before it spreads elsewhere? Yes, according to the simulations.

The H5N1 strain of the avian flu virus has infected a number of species, including domestic poultry, pigs and people. Scientists fear that a genetic exchange between bird and human flu viruses or the accumulation of H5N1 mutations could soon make efficient person-to-person transmission possible. With bird flu continuing to spread in Southeast Asia, the researchers decided to model a hypothetical human outbreak of H5N1 in this region.

Both models incorporated detailed data for Thailand on population densities, household sizes, age distribution, distances traveled to work and other factors. They also included information about the flu virus, such as the possible contagiousness of an infected person. The goals were to visualize how an outbreak might spread and to test the effectiveness of possible intervention strategies, such as the selective distribution of antiviral medication, vaccination and quarantine.

Although the models differed in the specific scenarios they simulated and the containment measures they evaluated, the general conclusions were similar: Preventing a pandemic would require a combination of carefully implemented public health measures introduced soon after the first cases appear. The need for additional measures, the models suggest, increases as the virus becomes more contagious. The results appear in online editions of Science and Nature.

Because computer models cannot capture all the complexities of real communities and real outbreaks, the researchers will continue to refine their simulations and test different scenarios as new information becomes available.

"As these modeling approaches develop," said NIGMS director Dr. Jeremy Berg, "they will offer policymakers and researchers powerful tools to use in strategic planning."

Led by scientists at Imperial College in London and Emory University in Atlanta, this new work is part of the NIGMS Models of Infectious Disease Agent Study research network, which strives to develop computational models of disease spread that will aid the development of effective control strategies.