Des expériences antérieures (1983-2002) concluent ainsi: les pigeons sont résistants à la grippe aviaire.
Lien télé du 29.10 (mon passage à la télé à ce sujet):
http://relations.france2.fr/mediateur_videos/29-10-2005.asx
http://www.albertaclassic.com/chalmers3.php
Avian Influenza ('Bird Flu') and Pigeons
--------------------------------------------------------------------------
by
Gordon A Chalmers, DVM
Lethbridge, Alberta, Canada
Email: Dr. Gordon Chalmers
Now, what is the role of pigeons in Avian Influenza? To answer that question more fully, we can look at some past examples of outbreaks of the disease in poultry in North America, plus the current one in Asia, and the tests that were conducted on pigeons collected from areas in which the disease occurred.
In late 1992, antibodies to Avian Influenza were found in blood samples from a commercial flock of turkeys in the north-eastern USA. (Note that antibodies are protective substances that are produced by the defensive network of the body in response to an infection). Investigation showed that there was a possible association between this flock and live bird markets. An influenza virus designated H5N2 was isolated from birds in one location. State jurisdictions were concerned by this situation and took both control and eradication measures when appropriate. Public poultry markets, shows and exhibitions were quarantined and premises on which the virus were isolated and depopulated.
Because of the very great concern by state and federal officials for the health and economics of the poultry industry in several jurisdictions in the USA, racing pigeons were included under the umbrella of domestic poultry, and accordingly, racing was banned in a number of concerned states. To date, however, the body of scientific evidence indicates strongly that pigeons are not involved in the transmission of Avian Influenza to domestic poultry.
During an outbreak of Avian Influenza (H5N2) nine years earlier (1983-84), again in the north-eastern USA, scientists conducted a survey of wildlife to determine the potential of wild birds to spread disease locally among farms, or to carry the virus to more distant locations.
Included in this survey were
1.. wild and free-flying domestic ducks and geese,
2.. wild or free-flying domestic birds closely associated with poultry farms, poultry manure, or poultry carcasses,
3.. mice and rats found inside and around houses containing infected poultry, and
4.. wild birds of any species reported sick or dead within the quarantine zone.
Tracheal (windpipe) and vent swabs from birds and lungs from mice and rats were examined for virus. As well, in some instances, toes from birds and rodents were also collected for the same purpose. When feasible, blood samples were also obtained from birds and small rodents. Attempts to isolate virus were conducted on 4,132 birds and rodents collected within the quarantine zone. Included in this number were 473 pigeons (92.6% of these pigeons were obtained from known infected farms), 81 pigeon feet (all of them from influenza-affected premises), and seven mourning doves. None of the 4,132 samples was positive for influenza virus. Blood samples from 2,147 non-aquatic birds, including 383 pigeons, were negative for antibodies to Avian Influenza - an indication that infection by this virus had not occurred in these birds. An additional 313 birds, including 50 pigeons, collected from the quarantine zone, were also negative for influenza virus. It is important to note that experimental attempts to infect pigeons with this strain of Avian Influenza did not result in either multiplication of the virus in these pigeons, or evidence of antibodies in the blood. The results of all of these studies indicated that pigeons were not infected with Avian Influenza and did not spread it.
In the 1993 outbreak in the USA, in the period from February to May, blood samples were collected from 17 flocks of meat varieties of pigeons, mainly White Kings located within the quarantine area, for evidence of antibodies to Avian Influenza. Flock sizes varied from 2000 - 3000 birds, and represented a total of about 34,000 - 51,000 birds. Approximately 10 birds per flock were sampled, for a total of 160 birds. In every instance, all pigeons tested were negative for antibodies to Avian Influenza.
Another study published in 1996 on the susceptibility of pigeons to Avian Influenza, found that groups of pigeons inoculated with two strains of highly pathogenic influenza virus or two strains of non-pathogenic virus remained healthy during the 21-day trial period, did not shed virus, and did not develop antibodies to this disease - further evidence that pigeons are not a factor in the spread of this disease.
More recent evidence from experimental work in 2001/02 has shown that pigeons infected experimentally with the highly pathogenic form of the virus (designated H5N1, and of Hong Kong origin) did not develop signs of this disease and did not have detectable changes to this disease in their tissues. As well, virus was not found in their tissues and neither was it re-isolated from swabs of tissues. These findings indicated once again that pigeons (along with starlings, rats and rabbits used in these studies), are largely resistant to infection with this virus.
Despite these reassuring findings, fanciers should be aware of the very slight possibility that if a returning race bird, or any wild bird for that matter, drops into a poultry farm on which the chickens are infected with Avian Influenza; it could pick up the influenza virus on its feet as it walks through droppings from these infected chickens. If this bird were to fly to another poultry farm, in theory it could be a mechanical means of spreading the virus on its feet to chickens on the second farm. The importance of this fact is that Type A influenza viruses can remain viable for long periods at moderate environmental temperatures, for four days in water at 22oC (72oF), and for over 30 days at 0oC (32oF). However, as noted in earlier studies, the feet of pigeons collected from affected poultry farms were examined for influenza virus and all were found to be negative.
Given this information from the scientific literature, it is important to note the non-role of pigeons in the spread of Avian Influenza, and the fact that pigeons themselves are not infected by this virus.
The reasons for the understandable caution and concern by regulatory agencies when they are faced with outbreaks of Avian Influenza include the fact that it can be a very costly disease. For example, the US government spent over $60 million in 1983-84 to eradicate a highly pathogenic H5N2 virus in poultry flocks (both chickens and turkeys).
I hope that this brief look at Avian Influenza and the non-role of pigeons in the spread of this disease to poultry will be of some assurance to concerned fanciers. Further information on this disease can be obtained from federal or provincial/state governmental agencies.
This page was last up-dated on April 13, 2004
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http://www.avian-influenza.com/Disease/AI_in_poultry/ai_pigeons.asp
En bref, il s'agit de deux expériences conduites par Intervet. On a injecté des virus de la grippe aviaire (entre autre le fameux H5N1) dans des pigeons qui n'ont montré aucun signe de maladie, même pas après 21 jours.
Par après aucune trace du virus n'a été retrouvé dans leurs corps, contrairement à d'autres espèces de volaille.
Les textes complets peuvent se lire sur:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11924603&dopt=Abstract
et
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8883790&dopt=Abstract
Ces deux liens se trouvent sur le site d'Intervet à propos de la grippe aviaire:
http://www.avian-influenza.com/
Qui est Intervet?
http://www.avian-influenza.com/about_us.asp
Une compagnie d'origine hollandaise -siège social international : près de Rotterdam qui à l'origine ( 1969) s'occupe de vaccins pour volailles te maintenant produits des vaccins pour tous les animaux et des additifs pour les animaux de production.
Ils on des centres de recherche en Allemagne, France, UK, USA, Norvège et Singapour:
http://www.intervet.com/company/research_and_development.asp
Leur site en France:
http://www.intervet.fr/
******************************
Le texte ci-dessous est une interview de NPR avec le docteur Hon IP.
Je traduis les idées générales des extraits intéressants que j'ai indiqués en grosses lettres dans le texte original. Dr. Hon Ip est virologiste et directeur du laboratoire de virologie du USGS (United States Geological Survey's Diagnostic Virology Laboratory) au Centre National de Santé de la Faune à Madison, Wisconsin; il répond à des questions au sujet du virus de la grippe aviaire et comment il se répand.
Selon lui:
1- en faveur de nos oiseaux des villes:
"Les espèces aviaires ne sont pas toutes susceptibles de façon égale au virus de la grippe. Des virus de grippe aviaire sont trouvés généralement dans des oiseaux aquatiques (des canards et des oies), des charadriformes et des mouettes. Les oiseaux tels que des moineaux et des pigeons n'ont pas tendance à être aisément infectés."
2- en faveur des oiseaux migrateurs:
"Si le virus est vraiment répandu par des oiseaux migrateurs-et jusqu'à maintenant il n'y a que des preuves indirectes de ce fait- il est bon de se rappeler que le virus du SARS qui provenait aussi d'Asie s'est rapidement diffusé par le biais des voyages internationaux. La grippe avaire pourrait donc se répandre non seulement par les oiseaux migrateurs mais aussi par le tourisme international."
Texte original: http://www.npr.org/templates/story/story.php?storyId=4967188
Interview with USGS Virologist Dr. Hon Ip
NPR asked health experts to answer listeners'
questions about bird flu.
Dr. Hon Ip, director of the United States Geological Survey's Diagnostic Virology Laboratory at the
National Wildlife Health Center in Madison, Wis., answers questions
about the virus and how it spreads.
What is Bird Flu and Who's At Risk?
by Robert Siegel and Melissa Block
Timeline
Oct. 19, 2005
The Spread of Bird Flu
Q: Can any migrating bird carry the flu virus or are there only
certain types of birds that will spread the flu? -- Laura Burrone,
New Haven, Connecticut
A: Not every species of birds is equally susceptible to the flu
virus, and not just migratory birds are susceptible. Avian influenza
viruses are found more commonly in water birds (ducks and geese),
shorebirds and gulls. Birds such as sparrows and pigeons tend not to
be as readily infected. It is not clear why shorebirds are more
susceptible to avian influenza infections and simple access to water
is not the answer, as even when birds are exposed directly to the
virus, species such as pigeons are more resistant.
Q: Has it been determined how long the virus survives on feathers
and down? Does the infectious agent die off in a certain number of
hours or does it have to be killed off via heat, etc.? -- Valerie
Doyle, Acton, Maine
A: Unfortunately, there is not a simple answer. Influenza viruses
are fairly environmentally resistant, which means they can survive
for long periods of time in the wild. The virus on feathers and down
is usually from fecal contamination and we know that the virus
remains infectious in contaminated feces for almost a week at room
temperature and up to three weeks in the cold.
There are a number of ways to kill the virus -- heat is a good way.
But just simple soap and water are excellent. Also many
disinfectants and commercial cleaners will work. The USDA Web site
has a number of examples of what can be used. (Adobe Acrobat
required.)
Q: Can mosquitoes be a vector for the spread of avian flu virus? --
Carol Taylor, Lovington, New Mexico
A: Influenza is not normally a disease that is transmitted by a
vector such as a mosquito. But because the virus is relatively
environmentally stable, mechanical transmission by insects, such as
flies, is a possibility. Since the virus can survive for long
periods in the wild, flies might pick it up when they land on feces
or infected birds, and then carry it to other animals. Mosquitoes
typically transmit diseases, such as West Nile Virus, by ingesting
blood from infected animals, then transmitting it to the next animal
they feed on.
Q: What early symptoms of bird flu should someone look for? -- Anne
Brodie, Aurora, New York
A: The true highly pathogenic avian influenza H5N1 can cause very
rapid death in susceptible birds. Sometimes the first sign is that
birds have died without obvious clinical symptoms.
When signs of infection are present, the birds may have respiratory
symptoms such as sneezing and coughing, swelling of the eyes and
combs and wattle, their feathers are ruffled, they stop laying eggs,
and they may have diarrhea.
Q: What makes this strain of bird flu so virulent (and does this
mean it spreads more easily or makes people sicker, or both?) --
Candy McLaughlin, Lexington, Massachusetts
A: That is a great question and not only is the answer complicated,
we don't have all the answers.
There are a number of genetic differences in the H5N1 virus that,
for example, allow the virus to grow in cells throughout the body of
a bird. Other avian influenza strains can only grow in the
respiratory and intestinal tracts. This allows the H5N1 virus to
cause more damage to more organ systems.
Other genetic changes allow the H5N1 virus to bind to surface
molecules on human cells, something that other avian influenza
viruses cannot do. Since binding is a necessary first step of
getting into the cell for the virus to replicate, these kinds of
changes (which are in the hemagglutinin protein) allow the H5N1
avian virus to infect people.
Q: Is the media exaggerating the potential danger of bird flu? --
Joyce Kuzmin, Boston, Massachusetts
A: There is a lot of coverage in the media, and it's hard to keep up
with what everyone is saying, but I think the issue is important.
Highly pathogenic, H5N1 is a clear danger to poultry and its threat
to wild birds is real. Although the number of human cases has been
small so far, the potential for the virus to change into a more
serious threat to humans is also real. So some level of public
awareness, including media coverage is appropriate.
Q: What's the probability of an individual U.S. resident contracting
avian flu at this point compared to other events, such as being
struck by lightning? -- Len Anderson, Sylvania, Ohio
A: As of right now, there is no evidence of bird flu being in North
America. Not in people, not in poultry, not in wild life. In the
United States, on average, something like 82 people die per year
from lightning, so since bird flu is not yet in this country, I
would say that the possibility of a U.S. citizen dying from
lightning is much higher than dying from H5N1 -- at the moment.
Q: I'm wondering what is the vector of transmission from bird to
human? Do you have to be in contact with bird feces? Do you have to
be in contact with bird blood products? How is it transmitted from
the bird to the human being? -- Chris (Last Name Not Provided),
Brewster, New York
A: Almost all human cases have been traced to close contact with
infected poultry. We think the process of raising chickens and
preparing chickens in Asia -- the home slaughter, plucking feathers,
preparing it for the table -- introduces a number of ways in which a
person can become infected. There have been very limited examples of
human to human transmission. I think that it's really extended,
prolonged contact with poultry -- as they are struggling, flapping
their feathers, releasing dander and other material -- that is
probably the route of infection.
Contact with bird feces, yes, that is definitely a way people could
become infected. Eating raw, contaminated (poultry) blood has been
suggested as one of the ways people have become infected in Vietnam.
Q: Is it possible for migrating birds to carry the virus to North
America, or is exposure here more likely from people returning to
North America from other parts of the world that had the virus? With
the new strain of bird flu reaching places like Romania and Turkey,
should I reconsider my plans to travel there next year? -- Bob
Spaziano, Raleigh, North Carolina
A: Both are possible. It's possible for migratory birds
to carry H5N1 to North America. We at the Department of Interior and
our sister agencies are trying to figure out how likely that is. We
think that international travel was a major way that the SARS virus,
which also originated in Asia, spread rapidly around the world, so I
would say that both migratory birds and international traffic are
ways that the virus could come to this country.
You should check with the CDC and follow their latest guidelines for
travel to that region of the world.
Q: Can humans get bird flu by eating the meat of infected birds? --
Claudia Sandberg Larsen, Sacramento, California
A: Not if they thoroughly cook it first. The flu virus is readily
killed by temperatures reached in meat when the meat is completely
cooked, and that is about 160, 170 degrees Fahrenheit.
Q: Does owning a caged pet bird increase the possibility of passing
or catching the avian flu virus? -- Lisa Branson, Torrance,
California
A: Having a pet bird that's inside all the time, I don't think
that's a risk. Let me point out that it's illegal in the U.S. to
import pet birds from regions that are infected with bird flu. So
the likelihood of getting a pet bird that's already infected with
bird flu is relatively low.
Q: Let's say my dogs pick up a dead bird, a bird that died from
avian flu. Are my dogs at risk? -- Phil Travers, San Antonio, Texas
A: What we know today is that there is no reputable report of H5N1
being in any dogs around the world. The virus has surprised us at
every turn, and so I wouldn't say that it's impossible, but at the
moment, I don't think if a dog picked up a bird infected with bird
flu, that the dog would be likely to come down with bird flu.
Q: What "mutation" of the virus would have to happen for it to
change to person-to-person, and what factors would cause that
mutation? -- Sarah (Last name not provided), Denver, Colorado
A: That's a question that a lot of virologists are trying to answer.
And what we're trying to do is compare the genetic sequences of H5N1
with other known human pathogenic viruses. What we know, for
example, is that mutations on the hemagglutinin gene -- that's
the "H" in the H5N1 -- can allow the virus to bind better to cells
in the human respiratory tract. There are also mutations in a gene
called PB2 that seems to be important for infections into humans.
How quickly can it mutate? That's a very difficult question to
answer. There are a number of ways in which the virus can mutate. It
can mutate gradually over time, or it can recombine in a co-
infection in a person or in an animal, and when recombination
happens, that can introduce a lot of mutations very rapidly.
Q: Wouldn't we assume that this virus would be potentially mutating
in infinitely different ways in different instances? -- NPR's Robert
Siegel
A: That is quite correct, the virus is mutating randomly and it's
only when a particular mutation is advantageous for it to infect a
particular new host that the mutation becomes selected and takes
over.
Q: How big a threat is this to healthy adults? -- Audra Bassett,
Robbinsville, North Carolina
A: In a general flu epidemic or pandemic, the sick and the elderly
are a target and vulnerable population, because they are less able
to fight off an infection. According to the World Health
Organization data, what we know about the situation in Asia is that
healthy adults are being infected (by H5N1). In fact, the average
age of those infected in Vietnam seems to be between the ages of 17
and 31. This could be due to occupational exposure, or it could be
from a particular predilection of the virus, and I don't think there
are enough cases for us to know that at the moment.
Q: Based on what we know about the migration paths of birds, does
that lead you in any particular direction of where this virus might
spread? -- NPR's Melissa Block
A: We had initially anticipated that the virus would spread from
Southeast Asia up along the Asian continent over toward Siberia, and
possibly contact migratory birds in North America over in the region
of Russian Siberia and Alaska. But since this summer it looks like
the virus has really spread toward Central Asia and now into Romania
and Turkey. What this indicates to us is that the virus is spreading
along a different route -- spreading toward the Black Sea and the
Mediterranean fly way.
Now, at the moment, if the virus really is being spread by migratory
birds -- and there's only circumstantial evidence for that -- it
will spread potentially toward the countries around the
Mediterranean basin and possibly toward regions of Africa.
There are a handful of species that migrate from North America to
Europe. Where (the virus) now is, we do not think those (North
American) birds are going to be in contact with the current
migratory birds that are in the Black Sea.
***********************************************
A propos de pigeons encore des nouvelles, de provenance d 'Espagne, qui a aussi ses problèmes avec les pigeons. L'association ARCADYS, Valencia fait du beau travail pour leur défense, ainsi ils ont obtenu qu'à Valencia, des pigeonniers de ville soient installés + nourrissage par graines contraceptives.
Là où il y des plaintes de surpopulation prononcées, on essaie de la effrayer à l'aide d'un son éléctronique ressemblant au cri du faucon, ou bien la mairie fait attraper les pigeons, elle bague ceux qui sont sains et les relâchent, et euthanasie ceux qui sont malades.
Sanidad (Santé publique) mentionne à ce propos qu'il n'y a aucune raison de paniquer et en informe le public, car "en aucun cas, le pigeon ne peut être vecteur de la grippe aviaire.Voir le lien:
http://www.20minutos.es/noticia/56950/0/ultrasonidos/contra/palomas/
Les labos de Sanidad ont, de plus, analysé des cadavres de pigeons euthanasiés , et ont dû conclure qu'aucun pigeon n'était infecté du virus, voir le lien:
http://www.lasprovincias.es/valencia/pg051023/prensa/noticias/CValenciana/20
0510/23/VAL-CVA-123.html
Vegadeo, Asturias est aussi une municipalité avec une approche douce du problème (graines stérélisantes) Lien:
http://www.elcomerciodigital.com/pg050920/prensa/noticias/Concejos/200509/20/GIJ-CON-111.html
Je trouve qu'il faut féliciter la ville de Valencia et Sanidad, et la ville de Vegadeo et les encourager à continuer dans ce sens, et en plus parler de ce modèle aux autres municipalités des pays européens qui ont des problèmes de pigeons....
Plus on fait de la pub en faveur de pigeons, mieux ça vaut...c'est pourquoi je rêve d'un forum international.
Myriam
Voilà une partie des articles que j'ai consultés:
Y es que, controlar, sanar y reducir la población de palomas de las 32.000
que hay actualmente a las 20.000 que se estiman convenientes, se ha
convertido en una prioridad para el Ayuntamiento. Desde Sanidad se está
elaborando un nuevo plan junto a la asociación para la defensa de los
animales Arcadys, basado en la construcción de varios palomares en
jardines cerrados, donde los alimentadores depositarán un pienso esterilzante.
Mientras, la Concejalía acude allí donde recibe quejas de vecinos y
captura palomas para analizar su salud. Las que están sanas se anillan y se
sueltan, y las que están enfermas, se sacrifican.
En este sentido, Sanidad quiere dar un mensaje de tranquilidad, «puesto que la gripe aviar en ningún caso puede ser transmitida por palomas»
http://www.20minutos.es/noticia/56950/0/ultrasonidos/contra/palomas/
**************************************
http://radio-canada.ca/regions/Ontario/nouvelles/200510/21/009-pigeons-australie.shtml
L'Australie a imposé un embargo total sur les importations d'oiseaux du Canada. Canberra a placé en quarantaine un lot de pigeons de course provenant de l'Ontario, après avoir découvert que trois d'entre eux sont porteurs d'anticorps contre une forme de grippe aviaire.
Au pays, les autorités et les éleveurs tentent de rassurer la population.
Selon eux, la décision de l'Australie de déclarer un embargo sur toute importation d'oiseaux canadiens est exagérée, puisque des études scientifiques récentes démontrent que les pigeons, même s'ils peuvent développer des anticorps de la grippe aviaire, ne sont pas porteurs de la maladie et ne peuvent donc pas transmettre le virus.
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