Avian flu

The avian flu , so known under the name of avian plague , indicates a viral Maladie near to the Grippe due to an alternative of the Virus Influenza has , which infects the Oiseau X wild or domestic. This affection is transmissible between birds and more rarely with Mammifère S (of which the Porc which is at the same time receptive with the avian grippaux viruses and human), but it is usually not easily transmissible with the Homme. Certain species of birds, and in particular some Canard S are often carrying asymptomatic.

Classification of the virus

The Virus grippal Influenza has is classified according to the type of two of its proteins of surfaces, in 144 possible combinations (16 Hémagglutinine S × 9 Neuraminidase S). These 144 sub-types all seem to be able to infect all the species of birds, and currently six of them (H1Nx, H2Nx or H3Nx, or HxN1 or HxN2) have characteristics enabling them to infect the Man more easily, situation which can evolve/move if the virus transfers. Each sub-type can be declined in many variable, the more or less pathogenic ones.

Transmission of the virus

See also: Methods supposed of contamination of the wildlife by the avian flu, Migration of the birds

Transmission with the Man

The case of the Man contaminated by the animal is famous most frequent, while remaining rare. It appeared for example that the epizooty due to virus H5N1 has 2004 with 2007 hard struck the birds and especially of the poultries, but only a few hundreds the human ones. These human cases had in the majority of the cases be in close contact or prolong with poultries touched by an epizooty which evolves/moves in Panzootie (at the end of July 2006, 58 countries or territories notified infections of wild birds or breeding by H5N1 on three Continent S).

Transmission of the Man to the animals

Conversely, the Homme can exceptionally infect animals. This possibility was studied little, but was proven in experiments with the Chat and the Porc (that was suspecté since 1918 at the time of the Spanish Grippe).

Fight against the disease

Risk factors

The risk factors immediate can be related to the Stratégie of detection and fight against a pandemia/lack of vaccine, with a low reactivity, an insufficient preparation, a lack of antiviral and or a Monothérapie (only one drug, for a virus which with the reputation to transfer easily) and contextual factors and length and medium term.

Factor of emergence

Emerges from the disease can be due to ecological, agro-pastoral, agro-industrial factors and Zootechnique S, demographic factors, dead ends, phenomenon of resurgence of old viruses, times of detection of a new sub-type of virus of influenza has and the quality and relevance of the epidemiologic follow-up .

Position of WHO

The current location of the the animal World Health Organization, on this subject, is accessible by these two bonds: [http://www.oie.int/eng/avian_influenza/Fiches_IA.pdf]

The the World Health Organization (WHO) fears that the avian flu, if it were humanized, can of a Panzootie evolve/move in Pandémie likely to kill up to 100 million people among several billion Malade S. Of other evaluations consider from 7,4 to 320 million Mort S in one to two even three years, according to whether the Morbidité of the virus would be similar to that of pandemias of 1957 or 1968 (very weak Mortalité), or comparable with that of 1918 (These figures are obtained by multiplying the evaluations of mortality due to the Spanish influenza by the factor corresponding to the increase in Population since 88 years). To limit the problem of the lack of vaccine in the event of pandemia, in May 2007, six countries (Brazil, India, Indonesia, Mexico, Thailand and Vietnam, will receive up to 2,5 dollars million of Japan and the USA (immediate financing) to launch the industry of local production of vaccines.

Consequences of the Panzootie

Consequences for the biodiversity

The Risque S for the Biodiversité of the avian flu are known little about and depend on many factors, of which conditions of Biosécurité of the industrial and family breeding.

It is known that genetic diversity within a population is often a factor of reduction of the transmission risk Maladie S. But the current Stratégie S of fight against the Virus tend to still making move back the biodiversity in the poultries.

Cost of pandemia

With industrialization, the universalization of the dies and the development of the low temperature, these costs increased, the majority of the clinical cases relate to birds of breeding and especially the Dinde, then the hen and moindrement of other species (Caille/Perdreau, Canard S, Oie S, Autruche). These are thus the dies which undergo the economic by-effect, but also the dies of Abattage, transport or production and supply of Aliment S of the poultries.

Scenario possible

Three principal scenarios are evoked for a change allowing a Pandémie:

Passage and adaptation by the Suidé S savages (Wild boar in Europe) or of breeding : the organization of the Porc (but of other species could also be concerned) has target receivers at the same time avian Virus and human Virus S. It can thus contract the two viruses simultaneously and thus to constitute a crucible in which the two viruses can mix their genes and give rise to a new virus which can infect the man and against which nobody would not have immunizing defense. Both epidemic S of influenza of 1957 and 1968 probably rose from this process. They caused more than 1,5 million Mort S. In August 2004, of the Chinese scientists had announced at the time of the International Conference on the prevention of the avian flu and the SARS that viral strain H5N1 had been already detected at Porc S Chinese, but those were not infected by the human influenza “ ”.
Passage and adaptation at the man by contact prolonged : after a contact prolonged and recurring with the Man, the virus could little by little Muter ( genetic Glissement ) in another transmissible stock of Man to Man. Rigorous measurements of health protection should limit this last risk by removing this recurring contact. This is why some prefer to indicate the avian flu under the avian term plague or “bird influenza”, the term influenza remaining held with the alternatives adapted to the man (although they can also sometimes touch the pig, the cat or other species)
Passage and adaptation to the man of the virus in area Arctique where the raw meat consumption of animals is a alive Tradition : in these areas deprived of Wood, Fruit S and Légume S the consumption of raw Viande (richer in Vitamin S) is a tradition. The living beings in top of the pyramid which are the human ones, the Phoque S and some Cétacés consume likely birds or which one knows carrying H5N1 (example Oie of the harvests). It is known that these mammals are potentially sensitive to the H5N1. One moreover, noted at the time of preceding pandemias that the Eskimo populations and Inuit S were particularly affected, in particular expressed as a percentage of the population killed by the virus. [http://alaska.usgs.gov/science/biology/avian_influenza/faq.html]

Mobilization vis-a-vis pandemia

If the question of the avian flu quickly mobilized so much expert and of international agencies, of which UNO, the the World Health Organization and FAO, it is because of possible “a humanisation ” of the virus H5N1, which in addition seems also dangerous - if it is not any more - that of the Grippe of 1918, which is today only with which one can compare it in term of Virulence. It fails only the capacity to easily infect to him the Man.

In November 2004, Shigeru Omi, regional director of WHO estimated that the most careful evaluations give a report on seven to ten million deaths, but the maximum could be fifty million or even, in the worst of the Scénario S, hundred million.

End December 2004, Klaus Stöhr and another expert of WHO declare In a few months, nearly 30 million people would need to be hospitalized, a quarter of them would die ; Albert Osterhaus and other Dutch scientists estimate in May 2005 then that it belongs to the most optimistic predictions ".

The professor Didier Houssin, interdepartmental deputy in charge of the fight against this disease, declares the October 17th 2005 qu ' a pandemia grippale is inescapable without being able to envisage the date of it. It divides the opinion of Liam Donaldson, its English counterpart.

A possible humanized virus of the avian flu will have in any case to be circumscribes into two to four weeks , pointed out an expert of WHO, if not it would be then impossible to contain .

January 17th, 2006, the National Sanitary Surveillance Institute publishes in its weekly report that a pandemia grippale resulting from a change of a bird flu (H5N1 or other) could reach between 15% and 35% of the French population and would be responsible for approximately close 600 000 hospitalizations and 118 500 deaths are awaited in the absence of treatment or from vaccine.

According to the the World Bank, it would be necessary to implement a budget of a billion and half USD like means of countering pandemia. Moreover, if a pandemia were to be declared in a country badly prepared, the risk of violent reactions important, is justified by the Panique, on behalf of the population, in particular with regard to the distribution of the Masque S and the Antiviraux. For these reasons, a certain number of aspects of the fight plan remain confidential, like the places of manufacture and storage of the masks and antiviral, and it is possible that the distributions are made by using the means available of which the army.

Within sight of these elements, one includes/understands the importance to supervise, control and manage, as long as to make the virus with its source may be, i.e. in his animal tank, while in addition avoiding contaminating the animal starting from the human reserve of the influenzas saisonnières.
L' ecology of the virus however still is very badly included/understood. It is possible that intermediate species or playing a part of secondary tanks exist and were not located yet. The role and the impacts of animal domestication, as well as industrial and mondialized breeding of the poultries could be underestimated until about 2005. It in addition remains of many unknown factors as for the capacity of the virus grippal to adapt or circumvent the human strategies of fights (antiviral, vaccines, etc). This is why the international authorities has a presentiment of the Médecin S and Vétérinaire S to be worked in concert, with the ecologist S, the managers of Crise, the political officials and with the Citoyen S by evaluating the Risque best, by establishing scenarios and by testing the answers by means of credible and transparent exercises.

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