What is the public health risk associated with this disease?

The disease is a zoonosis (a disease which primarily affects animals, but causes disease in humans). AI viruses are highly species-specific, but have, on rare occasions, crossed the species barrier to infect humans. Transmission to humans has occurred when there is close contact with infected birds or heavily contaminated environments. While AI caused by highly pathogenic virus strains have sometimes been shown to infect man, this disease should not be confused with seasonal human influenza, a very common human disease (generally caused by H1 and H3 viruses). Due to the potential for human infection, it is recommended that those people working with, or in contact with poultry suspected of being infected with AI, wear protective clothing including face masks, goggles, gloves and boots. The probability for the H5N1 AI virus to change to a form that is highly infectious for humans and that will spread readily from person to person is unknown. However, this possibility combined with the increasing resistance of the H5N1 AI virus to currently available antiviral treatment and lack of complete vaccination effectiveness make this a critical human health risk. There is no evidence to suggest that the consumption of cooked poultry or eggs could transmit the AI virus to humans.

What are the clinical signs of the disease?

In the mild form, signs of illness may be expressed only as ruffled feathers, reduced egg production, or mild effects on the respiratory system.

In the severe form of the disease, the virus not only affects the respiratory tract, as in the mild form, but also invades multiple organs and tissues that can result in massive internal haemorrhaging.

Some or all of the following clinical signs are evident in birds infected with a highly pathogenic strain of AI (including H5N1 strain):

• quietness and extreme depression;
• sudden drop in production of eggs, many of which are soft-shelled or shell-less;
• wattles and combs become swollen and congested;
• swelling of the skin under the eyes;
• coughing, sneezing and nervous signs;
• diarrhoea;
• haemorrhages on the hock;
• a few deaths may occur over several days, followed by rapid spread and a mortality rate that can then approach 100% within 48 hours.

source: http://www.oie.int/eng/en_index.htm