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Symptoms of Bird Flu

The term bird flu or avian flu is used to describe the influenza viruses that infect primarily the birds' population. In fact, birds appear to be a natural reservoir of flu viruses - 15 subtypes influenza A virus are known to be circulating in bird populations. Humans have caught the disease but only in small numbers as a few very rare cases have been noticed in the Far East .

Many forms of bird flu virus cause only mild symptoms in the birds or no symptoms at all. However, some of the viruses produce a highly contagious and rapidly fatal disease, leading to severe epidemics. These virulent viruses are known as "highly pathogenic avian influenza" and it is these viruses that cause particular concern. One such avian flu virus is currently infecting chickens in Asian countries .

The main symptoms of bird flu in birds or poultry are depression, loss of appetite, cessation of egg laying, nervous signs, swelling and blue discoloration of combs and wattles due to disturbance of blood circulation, coughing, sneezing and diarrhea. Sudden death can also occur without any previous signs. The mortality rate may reach up to 100% depending on the species, their age, the virus type involved and environmental factors like concurrent bacterial infections. Clinical signs of bird flu consist primarily of mild respiratory disease, depression and drop in egg production in laying birds.

Symptoms of bird flu in humans range from typical flu-like symptoms such as:

• Sore throat
• Cough
• Fever
• Pneumonia
• Respiratory distress
• Respiratory failure
• Life threatening complications