Transmission
-AI is not an air-borne infection.
-It is acquired by direct contact or by indirect contact with contaminated material (e.g. faeces of infected birds).
-There is currently a large threat of this in Asia with infected poultry due to low hygiene conditions and close quarters.
-There are many strains of AI viruses which vary in their ability to cause disease (pathogenicity). They are categorized as either highly pathogenic avian influenza viruses (HPAI) or low pathogenic (LPAI). It is thought that LPAI is common amongst European poultry.
-HPAI can spread easily and quickly between birds in poultry populations and cause severe disease, with a high death rate. In rare cases, some HPAI strains have lead to severe disease and deaths in people where infection has resulted from close contact with infected birds.
-The highly pathogenic H5N1 strain of the virus became known in South East Asia in 2004, and has led to the destruction of millions of birds. A series of H5N1 outbreaks in domestic and wild birds have occurred across Europe, including Great Britain, but with early detection and effective control these were eradicated quickly.
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| The red regions are the areas that have reported poultry deaths due to H5N1, dark red shows sountries that have had human infection with H5N1. It is clear that Asia is most severely affected. |
Symptoms in Birds
-oedema (swelling) of the head
-cyanosis (blue discolouration) of the comb and wattles (neck and throat area)
-dullness, a loss of appetite, respiratory distress, diarrhoea and a drop in egg production.
Extra Information
Health experts are concerned that the coexistence of human flu viruses and avian flu viruses (especially H5N1) will provide an opportunity for genetic material to be exchanged between species-specific viruses, possibly creating a new virulent influenza strain that is easily transmissible and lethal to humans. The mortality rate for humans with H5N1 is 60%.
Although millions of birds have become infected with the virus since its discovery, 359 humans have died from the H5N1 in twelve countries.
