Bird Flu Facts



Education is the best defence against disease. These bird flu facts should go some way to helping you understand the disease and the potential threat it poses to humans.

Avian Influenza was first described as a disease entity in 1878 when it was given the name Fowl Plague. It wasn't until 1955 that a virus was identified as the cause of the disease.

The Avian Influenza virus is an influenza A type virus. The nomenclature of these type A virus subtypes (e.g. H5N1, H6N2 etc) is derived from their surface glycoproteins - Haemaglutinin and Neuriminidase. At last count 16 different Haemaglutinins and 9 different Neuriminidases had been identified, with the possibility of others being identified in the future. Each virus subtype is a combination of one Haemaglutinin and one Neuriminidase.

Clinically, Avian Influenza in poultry can be divided into Low Pathogenic Avian Influenza (LPAI) e.g. H6N2 and Highly Pathogenic Avian Influenza (HPAI) e.g.H5N1.

Humans can be infected by 3 types of Influenza virus - types A, B and C.

Influenza Type A viruses undergo antigenic drift - a gradual change in an already circulating virus.

Influenza Type A viruses also undergo antigenic shifts from time to time (roughly every 20 -40 yrs). This is where there is the sudden emergence of a new and different Influenza A subtype. Since it is an entirely new subtype, the body is completely susceptible to it.

If this new subtype is particularly virulent, it can lead to pandemics such as the "Spanish Flu" in 1918 that killed an estimated 20-50 million people world wide.(According to a recent National Geographic TV programme, scientists have shown that the virus type responsible for the 1918 outbreak originated in poultry).

This ability of the influenza subtype A viruses to change and adapt to different hosts is why Avian Influenza is such a potential threat to both the poultry industry and people.

As an example, in 2004 researchers showed that cats can be infected with the Avian Influenza H5N1 virus and that the virus could not only cause severe disease (and death) in cats, but also that cats could transmit the virus to other cats.

H5N1 has already caused over 100 human deaths worldwide since 2003, but most of these have been people who have had long and close contact with infected poultry. At the time of writing, only a single case of human to human transmission of "bird flu" has been documented.

However, as the Avian Influenza virus continues to evolve and change, there is a chance that it will adapt to allow human to human transmission. If that virus is very virulent, then another flu pandemic in humans is likely.

The H5N1 virus is quickly killed at 70C. Thus normal cooking of chicken meat will kill the virus.

These bird flu facts should encourage you to find out more about Avian Influenza (bird flu)

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