Avian flu: Don’t fear the flocks yet
It’s November, which means that the snow geese are pouring into Oregon’s Klamath Basin in the hundreds of thousands. The sight of the undulating flocks, snow white against slate blue storm clouds, is unspeakably beautiful.
These are tundra geese, passing through en route to winter quarters in California’s Central Valley. They have come all the way from arctic Canada, from Alaska, and perhaps a few even from Ostrov Vrangelya, in the Russian Far East. That is, from Asia, from the homeland of avian flu.
The news has been full of reports about avian flu and the possibility that this disease could become a deadly global epidemic. Increasingly, those reports have highlighted the possible role of wild birds in spreading avian flu along their migration routes. For years, I have looked forward to arrival of the great waterfowl flocks every fall. As the time approached this November, I found that anticipation was tinged with a trace of fear. So I decided to review the facts about avian flu and migratory birds.
Although many mild strains of avian flu occur in wild birds, especially waterfowl, the deadly varieties are thought to arise in domestic poultry flocks, where crowded conditions are ideal for their spread. The particular avian flu virus that is the center of all the current concern is called H5N1. This highly pathogenic strain was never recorded in wild birds before it appeared in poultry flocks in Southeast Asia. Since its appearance, H5N1 has killed uncounted thousands of wild birds as well as millions of domestic chickens and ducks.
So far, about 120 people — all in Southeast Asia — have been infected with H5N1, over 60 of whom have died. While this form of avian flu is a serious disease if it is acquired, it does not spread easily to humans, even those working closely with infected poultry. It is not the current strain that terrifies public heath officials: It is the possibility that this virus could mutate into a form that is highly infectious to, and between, humans. Such mutations have occurred in the past, most notoriously in the flu pandemic of 1918, which killed 40-50 million people worldwide.
But it’s important to emphasize that this deadly transformation is only a possibility; there is nothing inevitable about it.
The H5N1 virus has now spread outside of Southeast Asia, to China, Russia, Romania and Turkey. Most of these cases are explained by trade in infected poultry. In a few instances, however, it appears that wild birds are carrying the virus along their migratory routes. It’s easy to miss that the ‘spread" being discussed in media reports is from wild birds to poultry, not to people. There is not a single case of human infection with H5N1 through contact with wild birds.
Nevertheless, the news that wild birds may carry the virus has led to some panicked reactions in Asia and the Middle East, including proposals to drain wetlands used by migratory waterfowl, and calls to kill (or ‘cull") wild birds in an effort to contain the virus.
This would actually make the situation worse by dispersing infected individuals and stressing healthy birds, increasing their susceptibility to disease. This view is shared by the World Health Organization, the Food and Agriculture Organization, the World Organization for Animal Health, and many other public health and environmental groups. These experts agree that the only effective containment strategy for H5N1 is to house poultry flocks in isolation from wild birds and infected water sources, and to conduct swift and complete culls of infected poultry flocks in the event of an outbreak.
H5N1 has not yet been reported from North America. Since the 1990s, the U.S. Department of Agriculture has sampled more than 10,000 migratory waterfowl crossing the Bering Sea from Asia to Alaska, but has not found a single bird carrying the H5N1 virus. Government agencies are now seeking $5 million over the next three years to expand virus testing to birds along their migratory routes in the lower 48 states beginning next spring. This is a prudent step that deserves our full support.
For me and millions of others, the observation of wild birds provides a blessed escape from the worries of the world. Avian flu is now certainly among those worries, but that should not diminish our enjoyment, or our protection, of these beautiful creatures.