Low-pathogenic forms of bird flu do cause illness among birds: Mild form of bird flu slows down migration of swans

These insights will be published on January 31, 2007 in PLoS ONE, the International, peer-reviewed, open-access, online publication from the Public Library of Science (PLoS) by scientists from the Netherlands Institute of Ecology (NIOO-KNAW) and the Department of Virology of the Erasmus MC. This contrasts previous ideas that mild forms of bird flu do not cause illness among wild birds. Moreover, these patterns can affect the rate of spread of avian influenza.

Wild birds were thought not to suffer from mild forms of avian influenza. But new data suggest that so-called ‘low-pathogenic’ avian influenza viruses do affect the lives of birds. The Bewick’s swan (Cygnus columbianus bewickii) is a migratory bird that breeds in NW-Russia and overwinters in NW-Europe, especially in The Netherlands. In this species, a team of ecologists and virologists showed that infected individuals initiate their migration by the end of January or early February, while uninfected individuals already do so by the end of December. Also, their next ‘fuelling station’ is only 35 km away instead of the usual 250 km. Sick birds fuel at a lower rate: they take fewer bites per day and their digestion seems to be impaired. Presumably, this is due to their need to channel more energy towards their immune system.

Being ill is no fun for us, but for a migratory bird being ill could potentially mess up its whole calendar for the rest of the year. According to scientist Jan van Gils from NIOO, “Infected swans clearly suffer from their ‘mild’ disease. The late departure from the wintering grounds could lead to late arrival in the breeding grounds, and thus to a lost breeding season. All in all, these low-pathogenic viruses have a much greater impact than previously thought. Because of their slower migration, ill birds get in touch with many more healthy birds passing by them on migration. In this way the virus can spread itself more rapidly than previously thought.”

Acquiring more knowledge about mild but illness-causing avian influenza viruses is very important. Van Gils adds, “These mild virus-types always formed the origin of massive pandemics such as the Spanish Flu. Only such viruses that are non-lethal to birds can be spread easily by (wild or captive) birds, simply because the birds stay alive.” Only after mixing with human flu can such a low-pathogenic avian flu cause the nightmare of a deadly pandemic among humans. “High-pathogenic avian flu that causes death among birds seems to originate from intensive poultry farms.”

In the Dutch study 25 swans were investigated. The birds were caught in polder Wieringermeer (NW-Netherlands) last winter and were measured, weighed and screened for the prevalence of avian influenza viruses. Twelve birds were equipped with a GPS attached to their neck collar (80 g in total). This enabled the researchers to follow the birds’ movements in great detail. When within 300 m of the bird, all “travel data” were downloadable by wireless modern technology. Birds were found back by volunteer bird watchers reading and reporting the code on each bird’s neck collar. Among the twelve neck-collared birds, two were infected with bird flu: type H6N2 and H6N8. These mild virus types are common among free-living waterfowl. From antibodies found back in blood samples it could be concluded that a few more individuals had been infected before but were fully recovered and behaved as the other healthy birds. Both birds that were infected last winter have returned this winter and seem fully recovered too.

Media Contact

Froukje Rienks alfa

Alle Nachrichten aus der Kategorie: Ecology, The Environment and Conservation

This complex theme deals primarily with interactions between organisms and the environmental factors that impact them, but to a greater extent between individual inanimate environmental factors.

innovations-report offers informative reports and articles on topics such as climate protection, landscape conservation, ecological systems, wildlife and nature parks and ecosystem efficiency and balance.

Zurück zur Startseite

Kommentare (0)

Schreib Kommentar

Neueste Beiträge

Detecting early-stage failure in electric power conversion devices

Researchers from Osaka University use non-destructive acoustic monitoring to identify the earliest stages of failure in silicon carbide power electronics, which will help in the design of more-durable power devices….

Build your own AI with ISAAC for error detection in production

Fraunhofer IDMT has developed a software tool for quality inspectors based on Artificial Intelligence (AI), which automates and simplifies the analysis of industrial sounds, for example in welding processes. Thanks…

BEAT-COVID – advanced therapy strategies against the pandemic

The present SARS-coronavirus-2 pandemic with all its effects on society – both health and economic – highlights the urgency of developing new therapies for COVID-19 treatment. At the same time,…

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close