Ducks transmit H5N1 virus through their respiratory system

26-10-2010 | Updated on 07-02 | |
Ducks transmit H5N1 virus through their respiratory system

The ‘classic’ avian flu virus H5N1 is causing a lot of worries and specualtions among experts. Juthatip Keawcharoen studied this virus and illustrated the role that wild animals, especially birds, play in its spread.

Keawcharoen will defend her PhD thesis today (October 25th) at Utrecht University in the Netherlands.
The H5N1 virus strain has been circulating since 1997, primarily in Asia. Outbreaks of this virus has lead to widespread mortality among poultry, but has also spread to humans, often with deadly results. The virus does not yet spread from humans to other humans, but the potential of a human pandemic is still present. If the virus were to mutate into a variant that spreads from humans to humans, then the effects could be much more serious than that of the Mexican flu, in which the human mortality rate was ‘only’ 0.2%. 
Keawcharoen was led to her research subject as a result of the infection of some tigers in a zoo in Thailand. She described the course of the infection and studied the role that migratory birds may have played in the spread of H5N1 from Asia to other parts of the world. Experimental research showed that the wild duck may have played an important part in the spread of the virus along the Eurasian route. This species of duck does not display many symptoms of infection, but does transmit large amounts of the virus. 
One unexpected discovery was that these ducks primarily transmit the virus through their respiratory system, instead of through their excrement. When tracking this virus in wild birds, it is therefore advisable to take samples from the beak or throat, as well as excrement samples. The doctoral candidate also made another contribution to diagnostics in detailing which organs can best be used to discover the H5N1 virus for a wide collection of wild animal species. This will significantly benefit the collection of data from field studies.
Keawcharoen’s further research in Thailand showed that wild birds play a role in the spread of the virus: a larger number of infected wild birds in the vicinity of poultry lead to an increase in the spread of the virus between poultry farms in the area. She therefore recommends keeping wild birds away from poultry farms.

Van Dijk
Zana Van Dijk Editor Dairy Global