Swine influenza

Swine influenza

Swine influenza is an acute respiratory illness caused by a swine influenza virus type A. It is endemic in pigs, with an estimated 25% of affected animals in the world. Its morbidity is high and its mortality rate is low. The virus is transmitted by direct and indirect contact and by aerosol, for sick animals or asymptomatic carriers. In temperate zone there are epidemic peaks in autumn and winter. Systematic vaccinations are carried out on populations of pigs in many countries.

Swine influenza viruses are the most common subtype H1N1, but other subtypes exist and pigs may be co-infected with several viruses at the same time, which can generate a recombinant virus derived from the mixture of different subtypes. These viruses normally infect pigs but they can sometimes pass the species barrier and cause disease in humans, usually in people in close contact with pigs. Few cases of interpersonal communications have also been reported. In 1976, it caused 25 deaths and the United States.

The virus of swine influenza has been isolated by Shope in 1930 while the human influenza virus was isolated in 1933 by Smith, Andrews and Laidlaw.

Swine influenza is caused by influenza viruses, enveloped RNA virus belonging to the subfamily of pigs Orthomyxoviridae endemic, gender and Influenzavirus subtype H1N1 or H3N2 mostly. These are type A viruses such as H1N1, H1N2, H3N1 and H3N2. Recently, research has indicated that the H2N3 virus could also be the cause of this type of influenza. The viruses isolated from pigs and humans have a common origin and exchange of viruses commonly occur between these two species.

Researchers are currently studying the relationship was originally established between the triple hybrid of influenza A (H1N1) and mega-hog dirty, dangerous and inhumane.


* Cash used: pork, and rarely humans, in birds such as waterfowl, for example.
* Sources and transmission of infection: the virus is excreted in the external environment by patients or carriers of the virus in aerosol form, or in the nasal or tracheobronchial. The virus can also be transmitted indirectly by vehicles, manure, etc. sidewalks.

Clinical picture
* Duration of incubation: 24 to 48 hours
* Symptoms: fever high (41 ° C), sudden anorexia, prostration and muscle aches.

Onset of respiratory difficulties leaving a dry cough, deep and quinteuse and jetage abundant. Healing takes place between the 6th and 8th days.

Diagnostic experimental

* Enhancing the pathogen by the reaction of hemagglutination or immunofluorescence techniques.
* Assessment of swine flu. by inhibition of hemagglutination or by radial hemolysis.


* Health: isolation of sick animals, the maintenance of good conditions for livestock and hygiene
* Medical: inactivated virus vaccine
* Passive: Port of a protective mask FFP which provides protection superior to that of surgical masks.

Epidemic 2009
In April 2009, a hitherto unknown variant of a virus genome comprises recombinant virus of swine influenza, avian flu and human influenza, known as influenza A (H1N1), appears.

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