Avian influenza is flu infection in birds. The disease is of concern to humans, who have no immunity against it. The virus that causes this infection in birds can mutate (change) to easily infect humans. Such mutation can start a deadly worldwide epidemic. Symptoms Although the exact incubation period for bird flu in humans isn't clear, illness seems to develop within one to five days of exposure to the virus. Common signs and symptoms: Most often, signs and symptoms of bird flu resemble those of conventional influenza, including:
- Sore throat
- Muscle aches
- A relatively mild eye infection (conjunctivitis) is sometimes the only indication of the disease.
Severe signs and symptoms: People with bird flu also may develop life-threatening complications, particularly:
- Viral pneumonia
- Acute respiratory distress, the most common cause of bird flu-related deaths