February 1, 2007

Research finds low-pathogenic bird flu impair birds' performance

Wild birds affected by low-pathogenic bird flu depart later on their migratory routes, feed slower and fly shorter distances, according to scientists from the Netherlands Institute of Ecology (NIOO-KNAW) and the Department of Virology of the Erasmus MC.

The study would be published in PLoS ONE, the International, peer-reviewed, open-access, online publication from the Public Library of Science (PLoS).

This contrasts with common belief that mild forms of bird flu do not cause illnesses.

Migratory birds such as Bewick's swan start migration up to a month later and is liable to stop and rest more often. They also eat less as their digestion seems to be impaired, with more energy having to be reserved for their immune system.

Because of their slower migration, ill birds come into contact with many more healthy birds passing by them on migration, thus spreading the virus more widely, scientists said.

Scientists said such mild virus-types could form the origin of massive pandemics if it mixes with human flu. While low pathogenic bird flu seems to originate among wild birds, high-pathogenic bird flu that causes death among birds seems to originate from intensive poultry farms, the study said.

Wild ducks in at least 5 US states tested positive for low pathogenic bird flu last year. The USDA in October last year downplayed the significance of these occurrences and said it would stop issuing news releases on low pathogenic bird flu found in wild birds as they pose no threat to human health.