Bird flu is an infection caused by avian, birds, influenza, flu, viruses. These flu viruses occur naturally among birds. Wild birds worldwide carry these viruses in their intestines but usually do not get sick from it. However bird flu is very contagious among birds and can make some domesticated birds: including chickens, ducks, and turkeys very sick and ultimately kill them. Bird flu viruses do not usually infect humans, but several cases of human infection has been reported since 1997. There are many different subtypes of type A influenza viruses. These subtypes differ because of the protein contents in the surface of the viruses. Bird flu viruses are those chiefly fond among birds, and the usually do not infect humans. For human flu viruses there are three a subtypes, H1N1, H1N2, and N3H1. Influenza A viruses are constantly changing and over time may adapt to infect humans and caused a spread or even pandemic proportion.

Efforts are being made to develop an effective vaccine for H5N1 virus, however this vaccine might not be effective against a new strain of this virus when and if it makes the leap from man to man. Infected birds shed these viruses through its saliva, nasal secretions, and feces. Susceptible birds become infected when they come in contact with these droppings, saliva, or nasal secretions. Exposure would require close enough contact to expose a person to body fluids or body surfaces that contain the virus. Sneezing and coughing propels virus into the air in microscopic particles so that close contact may not be necessary for infection. Indeed, some respiratory viruses can remain infectious on surfaces such as doorknobs for up to 2 days so that close personal contact would not be necessary. In short, influenza is as infectious as the common cold. Symptoms of bird flu in humans have ranged from typical flu-like symptoms (fever, cough, sore throat and muscle aches) to eye infections, pneumonia, severe respiratory diseases (such as acute respiratory distress), and other severe and life-threatening complications. The symptoms of bird flu may depend on which virus caused the infection. Rarely, the spread of avian flu virus has been reported from one ill person to another, and transmission has not been observed to continue beyond one person The risk of humans being infected is very low because the virus occurs only among birds. The risk from bird flu is generally low to most people because the viruses occur mainly among birds and do not usually infect humans. However, during an outbreak of bird flu among poultry (domesticated chicken, ducks, turkeys), there is a possible risk to people who have contact with infected birds or surfaces that have been contaminated with excretions from infected birds. The current outbreak of avian influenza A (H5N1) among poultry in Asia and Europe (see below) is an example of a bird flu outbreak that has caused human infections and deaths. In such situations, people should avoid contact with infected birds or contaminated surfaces, and should be careful when handling and cooking poultry. In rare instances, limited human-to-human spread of H5N1 virus has occurred, and transmission has not been observed to continue beyond one person. Influenza A (H5N1) virus – also called “H5N1 virus” – is an influenza A virus subtype that occurs mainly in birds. It was first isolated from birds (terns) in South Africa in 1961. Like all bird flu viruses, H5N1 virus circulates among birds worldwide, is very contagious among birds, and can be deadly.The H5N1 virus currently infecting birds in Asia that has caused human illness and death is resistant to amantadine and rimantadine, two antiviral medications commonly used for influenza. Two other antiviral medications, oseltamavir and zanamavir, would probably work to treat flu caused by the H5N1 virus, but additional studies still need to be done to prove their effectiveness.