Influenza Type A
How to Identify Influenza Type A Viruses
Influenza viruses have been divided as Type A, Type B, and
Type C based on the difference in two proteins, which are
known as called nucleoproteins found on the surface of the
virus. Some animals, besides human beings, host influenza
Type A virus. Wild birds are their natural hosts but the viruses
do exist in mammals such as pigs, horses, whales, and also
in seals and some other animals.
Pathogenic Nature Of Influenza Type A Virus
Depending on factors such as the genetic configuration of
molecules and the degree of pathogenesis, influenza Type A
viruses have been divided as Low Pathogenic Avian Influenza
(LPAI) and Highly Pathogenic Avian Influenza (HPAI).
LPAI viruses typically cause soft flu in birds. However,
they may evolve into HPAI viruses, as observed in several
bird flu events. Some commonly known strains of the LPAI virus
include H7N7, H7N2, and N9N2. LPAI viruses are generally transmitted
to humans when they come in contact with either living or
dead birds that carry the virus. In humans, LPAI viruses might
cause mild symptoms like conjunctivitis (pink eye). These
symptoms are no different from the human flu viral infections.
HPAI viruses are the sometimes the cause of severe flu symptoms
and are usually fatal to birds. Some of the more commonly
known strains of the HPAI virus include H5 and H7 and their
subtypes such as H5N1, H7N3 and H7N7. It has been revealed
that certain strains of HPAI virus are completely mild to
some birds like ducks.
Common Influenza Viruses Between Birds And Humans
Some Influenza Type A viruses causes flu only in birds and
where as some affect both humans and birds. Those infecting
both humans and birds are of three main types: Influenza A
H5, Influenza A H7, and Influenza A H9.
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