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April 2007 |
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Avian Influenza and Your Small Poultry
Flock: Frequently Asked Questions
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How do I know if my
chickens or turkeys have avian influenza?
Mild strains of avian influenza may present no symptoms or will cause
sick birds and low levels of mortality. Moderate drops in egg
production or increased numbers of poor egg shells are additional
symptoms in laying hen flocks. These symptoms can easily be confused
with other small flock diseases such as Infectious Laryngotracheitis,
Fowl Cholera or Infectious Bronchitis. Mortality can range from 0% to
20% over a period of several days to weeks. In flocks with other
health problems such as worms or respiratory infections, half or more
of the birds may die. |
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Strains that have mutated to a deadly form of avian influenza are
obvious. It is not unusual for a deadly strain to kill half of your
chickens or turkeys in 24 hours. In laying hen flocks, a dramatic
drop in egg production is often the first sign. Chickens and turkeys
may display respiratory or nervous signs or die suddenly without
first appearing sick. Your ducks and geese may show little or no
signs of illness with any form of avian influenza infection and
often none will die.
Only submitting your birds to a veterinarian will tell you if the
mortality or egg production problem on your farm is being caused by
avian influenza. The signs of the disease vary too much from flock
to flock for you to be able to make a home diagnosis.
Where do the North American strains of avian
influenza come from?
In North America there are two major reservoirs or sources of avian
influenza:
1) Wild ducks and geese in Canada and the U.S. naturally carry a
wide range of avian influenza viruses. None of these North American
strains have been implicated directly in killing large numbers of
poultry and none are known to have made people sick. Of the many
variations of the virus found in wild waterfowl, a few have the
potential to mutate after they infect a poultry flock into forms
that will kill large numbers of birds. In strains native to North
America, the virus must cycle through thousands of domestic poultry
before it has the opportunity to change into a highly pathogenic
strain capable of killing large numbers of chickens or turkeys. No
cases are known where an avian influenza virus has mutated into the
deadly form in a small flock of chickens or turkeys. If the virus
does change into a deadly form, it can then spread to backyard
flocks and kill large numbers of birds.
2) The 100 or more live bird markets in New York, New Jersey and
other U.S. states are a man-made reservoir of the disease. At these
live bird markets, people can pick out live chickens, turkeys, ducks
and other animals that they can have slaughtered on-site or take
home to process themselves. Because of the large number and turnover
of birds at these markets, the virus has the opportunity to survive
by infecting the thousands of birds that pass through the markets on
a weekly basis. The virus also has the potential to mutate to a
deadly form under these conditions. The close contact between
thousands of people visiting the markets and the manure and feathers
produced by the birds is a potential human health problem.
Fortunately, no live birds markets that can act as effective
reservoirs of avian influenza are known to operate in Manitoba. To
be an effective reservoir, a market will likely need to operate 40
weeks or more each year and accept hundreds of new birds on a weekly
or monthly basis.
How is Asian H5N1 avian influenza
different?
Unlike the strains of avian influenza native to North America, the
Asian H5N1 strain can arrive in a form ready to kill chickens,
turkeys and other gallinaceous birds. It does not need to cycle in a
large flock of poultry before gaining the ability to kill large
numbers of birds. This strain of virus can jump from wild waterfowl
to your small flock of poultry and start to rapidly kill your birds
immediately. This virus has spread from southeast Asia to Russia,
Europe, Africa and the Middle East but has not yet been identified
in North America.
The Asian H5N1 strain of avian influenza is a significant concern
because it has demonstrated a very limited ability to infect people.
If this strain mutates to a form that can readily infection people,
the human health consequences could be severe.
What types of birds are affected?
Strains of avian influenza that have mutated into forms that kill
large numbers of poultry can readily infect and kill chickens,
turkeys, quail, guinea fowl, pheasants, pea fowl, and partridges.
Some pet birds such as parrots and finches can also be very
susceptible to the virus. There are contradictory reports as to
whether wild sparrows or starlings will become sick or shed any
virus. Wild and domestic geese may show some signs of illness such
as difficulty walking and some deaths may occur. Ducks are highly
resistant and will normally appear healthy if infected - although
some cases of sick ducks have been observed with the Asian strain of
the virus. Pigeons appear to resist most strains of the virus
although some mortality due to the Asian strain has been reported.
With the Asian strain of avian influenza, deaths have occurred in
swans and a variety of other wild waterfowl.
How do I catch "bird flu"?
For information on bird flu and people, read, "Avian Influenza," in
the Q & A section of the Manitoba Health webpage on Pandemic
Influenza. To find this and other avian influenza documents, visit
www.gov.mb.ca/pandemic .
Can I eat chicken and eggs?
None of the human cases of "bird flu" reported world-wide have been
associated with properly cooked eating chicken or eggs. Health
Canada does recommend properly handling and cooking of eggs and
poultry as a routine precaution (http://www.hc-sc.gc.ca/fn-an/securit/animal/avia-poul/index_e.html).
Carlyle Bennett
and Glen Duizer
Manitoba Agriculture, Food and Rural Initiatives |
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