Water: unlikely source of transmission for bird flu
Cornell researchers studied the
H5N2 virus to see if a hypothetical mutated form of the H5N1 virus could infect
people through drinking and wastewater systems. The study was published in a
recent issue of Environmental Engineering Science.
H5N2, a low-pathogenic avian
influenza (bird flu) virus is similar to H5N1, however, it is unknown if
H5N1 is more resistant than H5N2 to procedures used by the water management
industry, according to Araceli Lucio-Forster, lead author and a specialist at
Cornell's Department of Microbiology and Immunology.
Because H5N1 requires high-level
bio-safety facilities, H5N2 was used as a surrogate virus. Given the
similarities, if H5N1 entered the water treatment system "the virus should be
inactivated, which means treated water may not be a likely source of
transmission," said Lucio-Forster.
radiation - To test the effectiveness of UV radiation for killing
the H5N2 virus, researchers exposed the virus in drinking water and in
wastewater effluents to UV light at varying levels. The treatment was very
effective in killing H5N2 at levels within industry standards.
- For chlorine, the results were less definitive. Inactivation of H5N2 depends
on both chlorine concentrations and time of exposure. US treatment plants
typically treat drinking water with chlorine concentrations of 1 milligram per
litre for 237 minutes. Given these guidelines, researchers found that H5N2 (and
likely H5N1 as well) would be mostly inactivated. Further studies are needed to
see if the viruses stay active when they come out of faeces or are at different
pH and salinity levels.
digesters - The small laboratory-scale study found that bacterial
digesters also reduced H5N2 to undetectable levels after 72 hours (consistent
with industry standards). The researchers also found that higher digester
temperatures inactivated the virus more quickly.
Environmental Engineering Science
Cornell's Department of Microbiology and Immunology
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