Avian (bird) flu influenza is caused by viruses that are usually found in wild birds. These viruses can spread to domestic birds and can sometimes infect humans. Although humans are rarely infected with bird flu it can be very deadly.
Symptoms of bird flu usually begin 2 to 5 days after infection and can include:
- Sore throat
- Muscle aches
Bird flu is spread through contact with infected birds, and very few cases have been seen where it has been transmitted from person to person.