Avian influenza

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Bird flu, also known as avian influenza, a viral disease means close of influenza caused by a variant of the influenza A virus, which infects wild birds or domestic. This condition is transmissible between birds and, more rarely in mammals (including pork that is both responsive to the avian influenza viruses and human), but it is usually difficult to be transmitted to humans. Some bird species, in particular some ducks are often asymptomatic carriers.


Ranking Virus
The influenza virus Influenza A is classified depending on the type of two of its surface proteins, in 144 possible combinations (16 × 9 haemagglutines neuraminidases). These 144 subtypes appear to be able to infect all species of birds, and now six of them (H1Nx, H2Nx or H3Nx or HxN1 or HxN2) have characteristics enabling them to more easily infect humans, a situation that may change if the virus mutates. Each sub-type can be broken down into many variants, more or less pathogenic.

Transmission to humans
The case of humans infected by the animal is deemed the most common, but still rare. It was found, for example, that the disease caused by H5N1 has between 2004 and 2007 hit especially birds and poultry, but only a few hundred people. Human cases had in most cases been in close contact with poultry or extended affected by a disease, which changes panzootic (end of July 2006, 58 countries or territories have reported infections of wild birds or livestock with H5N1 on three continents).

Transmission from animals to humans
Conversely, the man may exceptionally infect animals. This possibility has been little studied, but has been experimentally proved with the cat and pork (it has been suspected since 1918 on the occasion of the Spanish flu).

Cost of the pandemic
With industrialization, globalization channels and the development of the cold chain, these costs have risen, the majority of clinical cases involving breeding birds and especially turkey, and then the chicken and anything other species (quail / perdreau, ducks, geese, ostrich). It is these sectors affected by the economic but also the routes for slaughter, transport and production and supply of food for poultry.

Possible Scenario
# Passage and adaptation by suidae wild (wild boar in Europe) or breeding: the body of pork (but other species may also be involved) possesses target receptors for both avian and human viruses. It can thus assume the two viruses simultaneously, and thus constitute a crucible in which the two viruses can mix their genes and create a new virus that can infect humans and against which no one immune. The two flu epidemics of 1957 and 1968 probably resulted from this process. They have caused more than 1.5 million deaths. In August 2004, Chinese scientists announced at the International Conference on the prevention of bird flu and SARS that the H5N1 virus strain had been detected in pigs Chinese, but they were not infected with the flu "humane".
# Passage and adaptation in humans through prolonged contact: after a recurrent and prolonged contact with people, the virus could mutate gradually (genetic shift) with another strain transmissible from man to man. Stringent measures of health protection should limit this risk by removing contact recurring. That's why some prefer to designate the bird flu under the avian influenza or "bird flu", the term reserved for the remaining flu variants adapted to humans (although they may sometimes touch pork, or chat ' other species)
#Passage and adaptation to humans of the virus in Arctic region where consumption of raw meat animals is a living tradition: in these regions devoid of timber, fruit and vegetable consumption of raw meat (rich in vitamins) a tradition. The living at the top of the pyramid that humans are, seals and whales consume some birds likely or known to be carriers of H5N1 (example goose harvest). We know that these mammals are potentially susceptible to H5N1. It was also noted in past pandemics that people esquimaudes and Inuit have been particularly affected, notably as a percentage of the population killed by the virus.

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