ABSTRACT

Influenza is a severe respiratory disease which causes several complications resulting in the hospitalization and death, particularly in elderly people. This disease is caused by a virus of the Orthomyxoviridae family and has been the cause of large pandemics and millions of deaths in the 20th century. Each 1 to 2 years emerge new epidemic Influenza A strains because of the introduction of punctual mutations selected in the two surface glycoproteins: Haemaglutinine (HA) and neuraminidase (NA). The new variants are capable to avoid the immune system and therefore it is not possible to produce a long lasting and effective response. The virus needs three characteristics to be considered potentially pandemic: Enter and replicate in a human organism, cause a disease and be easily transmitted from person to person. At this moment, H5N1 is the Influenza A subtype with the largest pandemic potential. It has accomplished with the first two requirements. It is unknown if it can complete the third criteria although experts coincide it could happened by genetic rearrangements or adaptive mutations. Nevertheless it is unpredictable to know when it will occur.

KEYWORDS

Influenza, H5N1, reservoir.

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