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.
Pepper Trail is a contributor to Writers on the Range, a
service of High Country News (hcn.org). He is a
biologist who lives and writes in Ashland,
Oregon.
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