Study suggests bird flu can be transmitted by migratory birds

Assumption that poultry poses main risk has to shift, says researcher

- Chin Hui Shan

Bird flu, or avian influenza, in humans is often thought to be contracted through close unprotected contact with infected poultry or contaminated environments, but a new study has found another potential pathway through which it can be transmitted.

Habitat destruction—such as through deforestation in coastal habitats—may be bringing migratory birds in closer proximity to communities, facilitating the spread of the disease between the wild flocks and humans, a new study found.

By studying 2,000 blood samples of people living in northern Sabah in Malaysian Borneo, the study, published in Nature Communications on Oct 17, found that poultry and non-poultry owners had antibodies to the H5 avian influenza. Along with statistical analyses, this suggested that for the study, there was no correlation between H5 exposure risk and contact with poultry.

Antibodies indicate past exposure to disease and can be used to understand what diseases people were previously exposed to, even if they were not diagnosed or ill.

The antibodies in these individuals reacted to the specific H5 virus strains that were found in wild birds, according to the study conducted by researchers from the Pandemic Sciences Institute at the University of Oxford, Borneo Medical and Health Research Centre at Universiti Malaysia Sabah, and the Saw Swee Hock School of Public Health at the National University of Singapore.

No human case of the H5 flu had been reported in those areas.

Complementing environmental data on habitats and distribution of bird species, the researchers found these individuals with the antibodies were living close to migratory shorebird habitats.

Bird flu occurs naturally among wild aquatic birds like ducks and geese and shorebirds like plovers and sandpipers. They can easily infect domestic poultry like chickens through direct contact or through contact with surfaces contaminated with the viruses.