Migratory Birds and Bird Flu

Are migratory birds responsible for the spread of Bird Flu?

When the avian influenza A(H5N1) virus was found in a mute swan in the village of Cellardyke in Fife, Scotland, experts and public were worried about wild birds spreading the bird flu. Britain's poultry industry is very worried. Their fears were compounded when 14 more swans tested positive for the A(H5N1) virus. How the birds became infected became a point of concern.

Thousands of mute swans that live in Britain are largely sedentary birds and the dead one might be a resident bird too and likely infected by a migratory bird wintering in Scotland.

The instant fear is that some migratory birds returning to their breeding grounds in Greenland, the Baltic regions etc. might be spreading the disease when they return to other countries.

International experts feared for the worst, about the disease spreading to Africa during the southward migration and a deadly backlash later when they return to Europe. Blissfully, that has not happened!

Specialists from Wetlands International, a non-profit organisation, sampled some 7,000 African wild birds for influenza viruses in winter 2005, on behalf of the Food and Agriculture Organization.

But not a single wild bird was found to be infected with A(H5N1). Interestingly, during the peak return migration season in April, only a few cases involving wild birds have been detected in Europe. In contrast since February, a number of cases were reported, implying no role for the spring time return migration.

The last cases to be reported (as of writing) are of a falcon in Germany, a few swans in France and a grebe in Denmark (28th April). The World Organization for Animal Health has confirmed it and many European nations have now lifted restrictions imposed on free ranging poultry industry.

It is believed that European wild bird cases in February might be due to the migration of infected wild birds to the warmer west from frigid Russian and Central Asian territories.

If that is true, they could never have carried the virus to Africa. Also, it is known that the virility of the viruses among wild birds tend to weaken as they migrate southward.

Even, the rampaging bird flu in poultry on farms in some African nations like Egypt, Nigeria and Sudan etc., might have been imported through infected poultry and poultry products form elsewhere.

Newer evidence from (researchers based in Hong Kong in February, 2006) suggest that some migratory birds infected with A(H5N1) may travel for long distances, (which is contrary to popular belief), and infecting vast areas in western china, Mongolia, Russia, Ukraine, Turkey, Romania and the Balkans etc.

Some bird specialists have even suggested a few wetland lakes in Central Asia and Russia may actually have the virus all the time, and this could be where the virus originates in Europe and Central Asia.

However they are at a loss on which birds are the carriers and how they transmit? Trucks and people can also play a role. As an expert noted, fertilizer made of manure from poultry is commonly used to fertilize fish ponds, where the migrating birds stop en-route. Probably an infection can be contracted there. The irony is that no one is sure.