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Avian
Flu
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History
of the NAWA
When the USDA was forced to regulate birds under
the Animal Welfare Act, they informed various
bird-keeping organizations of the need for input
in drafting the regulations since they had no
prior experience with regulating birds. To facilitate
a coordinated effort, AFA president, Dr. Benny
Gallaway, invited representatives from various
avicultural organizations to a meeting in Houston
in May, 2003 to establish a group to respond
to the USDA's request. As a result, the National
Avian Welfare Alliance (NAWA) was formed with
representatives from a broad cross-section of
bird specialty groups including, bird trainers
and avian veterinarians, as well as organizations
for keepers of racing pigeons, waterfowl and
pheasants, finches, softbills, and parrots.
It was decided that NAWA would function as a
roundtable between these organizations.
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Avian
Flu and Captive Birds
Prepared
by the National Avian Welfare Alliance
(NAWA) November 2005
An outbreak of Avian Flu in the United States
has great potential to cause the loss of valuable
breeding stock and rare bloodlines of captive
birds. This is not because Avian Flu will devastate
captive bird facilities. It is because there
is likely to be an overreaction to the presence
of avian flu as a result of media hype and unwarranted
public fear. The biggest threat to our captive
birds during the Avian Flu scare will not come
from the virus itself, but from government officials
who are likely to react to its presence by calling
for the euthanasia of every bird within a specified
radius of any Avian Flu case in order to appear
like they are doing something about a perceived
human health threat.
Avian Flu can become a Human Flu with the proper
genetic changes. This change is what epidemiologists
are concerned about with the H5N1 flu virus.
But what we don't often hear in media reports
is that once the flu becomes a human flu, it
is humans that will be spreading the virus not
birds. It is very difficult to catch Avian Flu
from birds because the virus is adapted to avian
biology. Once the virus becomes adapted to human
biology and gains the ability to be transmitted
from human to human, birds will no longer be
a factor in its spread. As long as the virus
is an AVIAN flu, it will only infect humans
on very rare occasions under extreme contact
with infected bird body fluids.
Avian Flu exists in many strains and is endemic
to wild waterfowl with local rates of up to
60% positive for some waterfowl, such as mallards,
but nearly all other varieties of birds have
a low rate of Avian Flu incidence. The presence
of Avian Flu in wild bird populations does not
mean that the birds are diseased. Because wild
waterfowl commonly harbor these viruses they
have developed resistance over many millennia.
They rarely suffer illness from Avian Flu viruses.
Instead, they act as the natural reservoir of
Avian Flu viruses. Migrating waterfowl can spread
the virus over vast distances. Although wild
waterfowl regularly harbor avian flu, they do
not come in close enough contact with humans
or with most captive birds in this country to
pose a serious threat to human or captive bird
health.
Avian Flu does pose a serious threat to the
poultry industry and it is one of the reasons
for an effective biosecurity program on poultry
ranches. Avian Flu in poultry can result in
anything from decreased egg production to significant
mortality. The disease was first described over
125 years ago and periodic outbreaks of avian
flu in poultry have frequently occurred around
the world, including the United States. Since
1997, for example, more than 16 outbreaks of
H5 and H7 influenza have occurred in poultry
within the United States. When Avian Flu is
identified in poultry, the infected flock is
quickly culled to prevent the virus from spreading
to additional poultry facilities.
Most Avian Flu strains are not highly lethal,
but Influenza viruses undergo frequent mutations
that change the pathogenicity of the virus strains.
There are two categories of pathogenicty; Highly
Pathogenic Avian Influenza (HPAI) and Low Pathogenic
Avian Influenza (LPAI). HPAI outbreaks can cause
mortality in wild waterfowl and can also cause
significant losses to domestic poultry. If poultry
is infected with LPAI they will be culled to
prevent the opportunity for the virus to mutate
to HPAI.
Commercial poultry flocks are maintained in
high density environments of genetically similar
birds. When this is coupled with the close contact
these birds have with fecal and other secretions,
it allows for rapid viral transmission and dispersal
through the flock. The lack of genetic variation
in domestic poultry contributes to their susceptibility
to disease and increases their mortality rate.
If a virus can easily infect one chicken on
a facility, it is likely to be able to infect
the rest since their immune systems will be
genetically very similar.
Exotic and native captive birds are kept under
very different circumstances than domestic poultry.
The density, or number of birds per square foot,
is much lower. Non-poultry avian immune systems
are also much more capable of fending off a
viral infection. This does not mean that birds
other than poultry are immune to the virus,
but that they are less likely to suffer the
losses that poultry will if exposed to avian
flu. Proper biosecurity can easily prevent avian
flu from infecting our birds.
Birds that are housed indoors are extremely
unlikely to become exposed to the virus since
they are not in contact with wild waterfowl.
Outdoor captive bird facilities are not likely
to become exposed provided biosecurity practices
are in place and due to the fact that these
birds do not leave their enclosures to commingle
with wild waterfowl. Sunlight and fresh air
also inhibit the ability of the virus to survive
long enough to infect a new host.
All imported birds must go through USDA quarantine.
During quarantine, the birds are tested for
Avian Influenza, among other diseases. In the
many years that testing has been performed on
exotic birds in USDA quarantine, there has been
only one isolation of Pathogenic Avian Influenza
in an exotic bird (a Pekin Robin with H7N1),
ref: Dennis Senne et al. in Avian Diseases 40:425-37(1996).
The isolated strain was not pathogenic to poultry
or humans. Imported and domestic exotic birds
have never been a source of HPAI infections
in the United States. Exotic birds are not a
significant public health risk for Avian Influenza.
There is a good chance that H5N1 Avian Flu could
make it here to the United States via migrating
waterfowl. The threat this poses to our birds
must be kept in perspective. Avian Flu, of one
variety or another, arrives every year in the
United States via migrating waterfowl. We do
not see Avian Flu infections of captive birds
as a result. H5N1 is no more likely to infect
our captive birds than any other strain of Avian
Flu.
Proper biosecurity should always be in place
to protect our birds from the various health
threats that are omnipresent. The possibility
of the arrival of H5N1 flu should serve as a
reminder to practice proper biosecurity, but
it should not be something to panic about.
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Bird
Flu Prevention and Protection Through
Bio-security Measures
Prepared
by the National Avian Welfare Alliance
November 2005
Bird Flu Carriers: Wild migratory waterfowl,
ducks and geese, are the primary carriers
of a variety of strains of bird flu
viruses, including the H5N1 subtype
which can be dangerous to humans. New
strains of H5 and/or H7 bird flu viruses
have always arrived every year. H5N1
is not in North America at this time.
H5N1, is rarely transmissible from infected
poultry to humans. Only people who have
contact with H5N1 infected poultry,
their feces, or water contaminated by
their droppings may become infected.
H5N1, is NOT transmissible from human
to human at this time, but it is feared
that H5N1 might mutate into a form that
is transmissible from human to human.
If H5N1 becomes transmissible from human
to human, birds will no longer be a
source of infection.
Standard biosecurity measures can protect
your birds from infection by various
diseases including the H5N1 virus. The
following simple measures can be taken
to protect your birds from exposure
to H5N1 and other infectious diseases.
- If
your birds are housed inside a building
or your home, and you have no poultry
at your home and you do not have
any free roaming poultry with access
to your facilities, your birds will
have no opportunity to contract
the disease. If you handle other
birds away from home or visit an
area with free-roaming waterfowl,
it is recommended to shower, change
clothing and disinfect shoes before
handling your birds.
- If
you do not visit or frequent feed
stores or other sites frequented
by individuals or farmers with free
ranging chickens, or other poultry,
you should have no opportunity to
pick up viral particles on your
shoes to track into your home or
facility.
- If
you have a small flock of poultry
that is contained in a building
or a securely fenced area with wire
enclosing the top portion so that
wild birds cannot enter, your poultry
will be protected from exposure
to bird flu from wild birds. However,
if you DO have any poultry located
at your facility, it is recommended
that you routinely wear special
footwear outside when feeding the
poultry, and remove that footwear
prior to entering your house or
exotic bird facility.
- If
you have a neighbor with free ranging
poultry, especially if they have
a pond which is visited by wild
waterfowl during migration, it is
recommended that you put in place
a security fence so that the free
ranging poultry cannot enter your
property.
- If
you have a pond on your property
which provides access to wild waterfowl,
and you have a flock of ducks or
geese or swans, it is recommended
that you corral the domestic or
exotic waterfowl so that they cannot
access the pond and contact the
wild migratory waterfowl or their
feces.
- If
you have family or friends who own
poultry or waterfowl, it is recommended
that you have them remove their
footwear prior to entering your
home or bird facility.
- If
you are feeding wild songbirds at
bird feeders, it is unlikely that
you will come into contact with
a bird carrying bird flu. However,
it is wise to wash your hands well
after handling and refilling the
feeder.
- If
you find a dead wild bird near your
birds, wear disposable gloves to
pick it up. Take it to a vet or
state lab for necropsy and testing.
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Bird
Flu is for the Birds!
Prepared
by the National Avian Welfare Alliance November
2005
Human influenza is a highly contagious disease.
Most of us have had the flu multiple times
in our lives. In the United States, influenza
epidemics occur nearly every winter and are
responsible for a substantial amount of illness
and deaths. Approximately 114,000 hospitalizations
and 20,000-50,000 deaths occur in the U.S.
on an annual basis as a result of the flu
(http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5107a1.htm).
If influenza is so easily transmissible, why
aren't more people catching the bird flu directly
from birds? The reason is that birds and humans
are different. The qualities that allow the
virus to easily infect birds don't work well
on humans.
Although it's true that avian flu viruses
can become human flu viruses, the typical
way a flu virus makes the jump from birds
to humans is by infecting a pig that just
happens to have a concurrent infection of
human flu virus - 2 different viruses in the
same animal at the same time. Pigs are more
easily infected by both types of viruses and
they serve as a sort of mixing pot. Different
types of influenza viruses can exchange genetic
material when they are exposed to each other
in the same host. This is called antigenic
shift.
Antigenic shift allows for large amounts of
new genetic information to be acquired by
the avian flu from the human flu virus when
they are exposed to each other. If the avian
flu virus acquires the genetic factors that
allow it to easily pass from human to human,
then it is possible for the avian virus to
make the jump to become a human influenza.
Because birds and humans are very different,
there are generally multiple factors that
must be acquired in order for the virus to
make the transition from avian to human flu.
The actual factors that allow an avian flu
virus to easily infect birds may prevent it
from easily infecting humans. Additionally,
the factors that allow the avian flu viruses
to easily infect humans are likely to alter
more than just the viruses' ability to infect
humans. It is also likely to alter the virus's
impact on the human body. In the case of H5N1,
this means it is just as likely to become
nothing more than the standard flu, as opposed
to the killer flu, if it makes the jump to
human influenza.
One of the reasons Asia is a breeding ground
for influenza is the animal husbandry practices
that are used there. Poultry can be brought
to markets where they are exposed to poultry
from other farms, and live birds are brought
back home if unsold. Ducks, poultry and pigs
are allowed to commingle on the farms where
there is very little biosecurity. Poultry
are allowed to free-range and domestic ducks
are allowed to graze in open wetlands where
wild waterfowl visit. This increases the likelihood
that avian flu viruses which are common in
wild waterfowl can mix with human flu viruses
which are common in pigs. This allows for
a shuffling of genetic traits between the
different strains of viruses which creates
new strains as a result. If the new strains
have the ability to infect humans easily,
then the farmer, or other people around the
livestock, will catch it and the virus spreads
through the human population from there.
Animal husbandry practices in the United States
are not conducive to the mingling of avian
flu strains with human flu strains. If H5N1
arrives in the United States via migrating
waterfowl, it is not going to have the opportunity
to acquire the traits necessary to become
a human flu virus here.
Influenza viruses also change their genetic
properties by simple random mutations. This
process is called antigenic drift, in contrast
to antigenic shift. Antigenic drift is responsible
for small changes in the genetic properties
of the virus. All influenza viruses mutate
regularly and thereby undergo antigenic drift
constantly. This is the reason we can't carry
immunity to the flu from one year to the next.
This year's flu will be different enough from
last year's flu so that our immune system
will not recognize it or have the proper antibodies
to fight it off. Although antigenic drift
can result in changes in pathogenicity in
avian flu virus strains, it rarely, if ever,
results in the significant genetic changes
required to allow an avian flu virus to make
the jump to becoming a human flu virus.
It is theoretically possible for an avian
flu virus to accumulate enough mutations through
antigenic drift to gain the ability to infect
humans easily, without antigenic shift or
an intermediate host involved, but this generally
requires a specific series of mutations to
happen. Because more than a single mutation
is involved, the odds of this happening are
very small. Any single mutation in the direction
that may lead to an avian flu becoming a human
flu is likely to cause that avian flu strain
to be less capable of infecting birds and
thereby surviving long enough to gain the
additional mutations necessary to complete
the jump. Even if an avian virus strain was
capable of accumulating the correct series
of mutations to become a human influenza,
those genetic changes are also just as likely
to reduce the impact the virus has on the
human body.
In order for an influenza virus to be easily
spread throughout the human population and
result in a pandemic, it must be mild enough
for people to be able to go out and spread
the virus once they are infected. If the virus
kills its victims quickly, as is the case
with the current strain of H5N1, there will
be dramatically less opportunities for the
virus to be transmitted from the victim to
a new host. The infection becomes what epidemiologists
call "self-limiting". Because a victim quickly
becomes too sick to get out in public, the
virus does not have the chance to spread to
a large number of people. This further illustrates
why the genetic changes required for H5N1
to become a human flu virus are unlikely to
cause it to become the deadly killer that
the media is playing it up to be.
The current pattern displayed by H5N1 illustrates
how difficult it is for avian flu viruses
to infect humans. Despite the fact that there
have been millions of H5N1 infected poultry
in Asia in the past few years, only a little
over one hundred human H5N1 cases have been
reported. This is a very small number in comparison
to the probability of numerous human exposures
resulting from the husbandry practices there.
Keep in mind that in Asia poultry are frequently
sold live to the consumer who must butcher
and prepare the bird themselves.
Since 1997, more than 16 outbreaks of H5 and
H7 influenza have occurred in poultry within
the United States. The virus strains in each
of these outbreaks were just as likely as
H5N1 to become human influenza viruses, yet
none of them made the jump from avian virus
to human virus. Of all the people exposed
to the avian flu during these 16 outbreaks,
according to the CDC (http://www.cdc.gov/flu/avian/),
only 2 mild cases of human infection in the
U.S. resulted.
Despite the media attention to Bird Flu, there
is no increased risk of catching the flu from
exposure to birds, other than poultry in Asia.
There have been no documented cases of humans
catching Avian Flu from pet birds such as
parrots, finches and other commonly kept species
(http://www.cdc.gov/flu/avian/).
All birds imported into the United States
have been routinely tested for pathogenic
Avian Influenza since 1974. Of the many millions
of birds imported during this 30 year period,
pathogenic Avian Influenza was only found
in 1 shipment of birds from China. Exotic
birds being legally imported into the United
States represent virtually NO risk of introducing
pathogenic Avian Influenza virus as they are
ALL tested during quarantine.
Exotic birds being bred for sale in the United
States represent virtually NO risk for Pathogenic
Avian Influenza unless they are co-mingled
with infected poultry and at this time pathogenic
Avian Influenza (H5 or H7 strains) are not
known to exist in the United States. USDA
is continually monitoring for the presence
of Influenza and New Castles Disease in domestic
"backyard" and commercial flocks.
It is important to understand that Bird Flu
or Avian Influenza is a disease of birds (mostly
poultry), and it is not readily transmitted
to humans. For many millennia, Avian Influenza
has existed in North America. It is found
in migrating waterfowl on an annual basis.
H5N1 is no more likely to infect humans than
the Avian Flu strains that arrive every year
yet do not infect humans.
If H5N1 gains the ability for human to human
transmission, it will be humans spreading
the disease to humans, not bird to human transmission.
A human version of the virus will most likely
enter the US by infected persons arriving
from outside the US on airplanes. The virus
will not arrive by imported birds which are
quarantined, and not by migrating birds. And
example of this type of disease transmission
was the spread of SARS into Canada. This disease
introduction was quickly recognized and brought
under control due to vigilance of medical
and regulatory personnel.
The fear of contracting bird flu from pet,
companion, or zoo birds in the United States
is totally unfounded. The chance of contracting
bird flu from native birds is also extremely
remote. Attention needs to be appropriately
placed on surveillance of incoming international
travelers if and when the virus shifts sufficiently
to maintain virulent human to human transmission.
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All influenza A viruses originated
in birds.
Influenza epidemics occur nearly
every winter and are responsible for approximately
114,000 hospitalizations and 20,000-50,000
deaths in the U.S. on an annual basis. (
http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5107a1.htm).
Although the annual influenza
viruses may have originated in birds, birds
are not involved in the spread of the influenza
viruses that infect humans.
For many millennia, new strains
of Avian Flu have been arriving in North
America via migrating waterfowl on an annual
basis. H5N1 is no more likely to infect
humans than the Avian Flu strains that arrive
every year yet do not infect humans.
The typical way a flu virus
makes the jump from birds to humans is through
an intermediate host such as a pig. Once
the virus becomes a human virus, it is humans,
not birds, which spread the disease.
Pet birds are NOT a risk factor
for catching the flu. There have been no
documented cases of humans catching Avian
Flu from pet birds such as parrots, finches
and other commonly kept species (
http://www.cdc.gov/flu/avian/gen-info/avian-flu-humans.htm).
Animal husbandry practices in
the United States are not conducive to the
mingling of avian flu strains with human
flu strains.
Since 1997, more than 16 outbreaks
of H5 and H7 influenza have occurred in
poultry within the United States. The virus
strains in each of these outbreaks were
just as likely as H5N1 to become human influenza
viruses, yet none of them made the jump
from avian virus to human virus.
Although there have been millions
of H5N1 infected poultry in Asia in the
past few years, only a little over one hundred
human H5N1 cases have been reported. This
is an extremely small number in comparison
to the large numbers of human exposures
there.
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