Avian influenza or bird flu refers to the disease caused by infection with avian (bird) influenza (flu) Type A viruses. These viruses naturally spread among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species. Bird flu viruses do not normally infect humans. However, sporadic human infections with bird flu viruses have occurred. The links below offer more information about bird flu.
Avian Influenza in Birds
Avian influenza refers to disease in birds caused by infection with avian (bird) influenza (flu) Type A viruses. Avian influenza A viruses have been isolated from more than 100 different species of wild birds around the world. These viruses occur naturally among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species. Wild aquatic birds include waterbirds (waterfowl) such as ducks, geese, swans, gulls, and terns, and shorebirds, such as storks, plovers, and sandpipers. Wild aquatic birds, especially dabbling ducks, are considered reservoirs (hosts) for avian influenza A viruses. Wild aquatic birds can be infected with avian influenza A viruses in their intestines and respiratory tract, but some species, such as ducks, may not get sick. However, avian influenza A viruses are very contagious among birds, and some of these viruses can sicken and even kill certain domesticated bird species, including chickens, ducks and turkeys.
Infected birds can shed avian influenza A viruses in their saliva, nasal secretions, and feces. Susceptible birds become infected when they have contact with the virus as it is shed by infected birds. They also can become infected through contact with surfaces that are contaminated with virus from infected birds.
Avian Influenza in Poultry (Domesticated Birds)
Domesticated birds (chickens, turkeys, ducks, etc.) may become infected with avian influenza A viruses through direct contact with infected waterfowl or other infected poultry, or through contact with surfaces that have been contaminated with the viruses.
Avian influenza outbreaks in domesticated birds are of concern for several reasons:
- the potential for low pathogenic avian influenza A(H5) and A(H7) viruses to evolve into highly pathogenic avian influenza A(H5) and A(H7) viruses with major agricultural implications
- the potential for rapid spread and significant illness and death among poultry during outbreaks of highly pathogenic avian influenza
- the economic impact and trade restrictions from a highly pathogenic avian influenza outbreak
- the possibility that avian influenza A viruses could be transmitted to humans exposed to infected birds
When avian influenza A(H5) or A(H7) virus outbreaks occur in poultry, depopulation (or culling, also called “stamping out”) of infected flocks is usually carried out. In addition, surveillance of flocks that are nearby or linked to the infected flock(s) and quarantine of exposed flocks with culling if disease is detected, are the preferred control and eradication methods
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