Avian influenza (Bird flu)
Bird flu is an infection caused by bird influenza (flu) virus. It is occur naturally in birds. Wild birds carry the viruses in their intestines, but generally do not get sick from them. However, bird flu is very infectious among birds and can make some domestic birds, including hens, ducks, and turkeys, very sick and kill them.
Humans and Bird flu:
There are several subtypes of type A influenza viruses. These subtypes vary because of certain proteins on the surface of the influenza A virus hemagglutinin(HA) and neuraminidase (NA) proteins. There are 16 different HA subtypes and 9 different NA subtypes of flu A viruses. Various different combinations of HA and NA proteins are possible. Each combination is a different subtype. All known subtypes of flu A viruses could found in birds. When we talk about human flu viruses we are referring to those subtypes that occur widely in humans. There are only three known A subtypes of human flu viruses (H1N1, H1N2 and H3N2); it is likely that some genetic parts of current human influenza A viruses came from birds originally.
Human Symptoms:
Bird flu symptoms in humans have ranged from typical flu-like symptoms (fever, sore throat, cough and muscle aches) to eye infections, severe respiratory diseases (such as acute respiratory distress), pneumonia and other severe and life-threatening complications. The symptoms of bird flu may depend on which virus caused the infection