Overview
Bird flu, also called avian flu or avian influenza (AI), is an infectious disease caused by strains of influenza A viruses. Avian influenza is highly contagious in bird populations throughout the world. It often spreads through the migration of water birds. While many types of wild birds can carry the influenza virus without becoming ill, other types of birds (e.g., domestic birds such as chickens, turkeys, and ducks) develop disease when infected with avian flu viruses.
In domestic birds, one form of avian flu is common and usually mild, and one form is rare and more severe. The mild form of the disease is called LPAI (low pathogenic or "low path" avian influenza). Symptoms of this type include ruffled feathers and low egg production. The severe form is called HPAI (high pathogenic or "high path" avian influenza). In birds, HPAI develops suddenly, spreads quickly, and often causes death within 48 hours.
Influenza viruses rarely infect other species; for example, viruses that infect pigs usually do not infect horses. When people are infected with these viruses, they usually develop only mild symptoms (e.g., cough, fever, muscle aches, eye infections).
Incidence and Prevalence According to the World Health Organization (WHO), outbreaks of bird flu in poultry have occurred in the following countries:
- Cambodia
- China
- Croatia
- Indonesia
- Japan
- Kazakhstan
- Lao People's Democratic Republic (Lao PDR)
- Malaysia
- Mongolia
- Republic of Korea
- Romania
- Russian Federation
- Thailand
- Turkey
- Viet Nam
Since November 2003, H5N1 avian influenza infection in people has been reported in 12 countries, including the following:
- Azerbaijan
- Cambodia
- China
- Djibouti
- Egypt
- Indonesia
- Iraq
- Lao People's Democratic Republic (Lao PDR)
- Nigeria
- Thailand
- Turkey
- Viet Nam
In 2007, the highest number of cases of H5N1 infection in people has occurred in Indonesia and Egypt. In most of these cases, human infection appears to have resulted from exposure to the saliva, nasal secretions, and feces of infected poultry or wild birds, for example, at a live poultry market.
Physician-developed and -monitored.
Original Date of Publication: 02 Aug 2007
Reviewed by: Stanley J. Swierzewski, III, M.D.
Last Reviewed:
Avian Flu (Bird Flu), Overview reprinted with permission from avianflu.healthcommunities.com
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