Amid concerns about a pandemic of swine flu, researchers from Nebraska report that poultry carcasses infected with another threat — the "bird flu" virus — can remain infectious in municipal landfills for almost 2 years.

Shannon L. Bartelt-Hunt and colleagues note that avian influenza, specifically the H5N1 strain, is an ongoing public health concern. Hundreds of millions of chickens and ducks infected with the virus have died or been culled from flocks worldwide in efforts to control the disease. More than 4 million poultry died or were culled in a 2002 outbreak in Virginia, and the carcasses were disposed of in municipal landfills, per recommendations by the U.S. Environmental Protection Agency

Until now, few studies have directly assessed the safety of landfill disposal.

"The objectives of this study were to assess the survival of avian influenza in landfill leachate and the influence of environmental factors," the report states.

The data showed that the virus survived in landfill leachate — liquid that leaches from a landfill — for at least 30 days and up to 600 days. The two factors that most reduced influenza survival times were elevated temperature and acidic or alkaline pH.

A key finding: The 600-day period is within U.S. guidelines for how long a landfill is supposed to retain leachate. So in theory, the virus should die in the landfill.

"Data obtained from this study indicate that landfilling is an appropriate method for disposal of carcasses infected with avian influenza," according to the study, which notes that landfills are designed to hold material for much longer periods of time.

The report will be detailed June 15 in the journal Environmental Science & Technology.

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