Avian flu is an Influenza A virus that infects both wild and domestic birds, and certain strains have been known to infect both animals and humans. Status of Avian Influenza Outbreaks

A strain of highly pathogenic avian influenza (H5N1) has spread throughout Asia since 2003, and has subsequently moved into Europe, the Middle East, and Africa. It has infected mostly poultry and wild birds, but a limited number of humans have contracted the disease through close domestic poultry-to-human contact. Over 250 million poultry have died or been destroyed internationally. Since wild birds can carry the highly pathogenic H5N1 virus, the U.S. Department of Agriculture (USDA) and the Department of the Interior (DOI) have increased surveillance of wild and migratory birds. Surveillance is particularly high in Alaska, where Asian and American flyways overlap. Migrating birds from Asia could carry the virus to Alaska, and infect birds from the Americas on shared nesting grounds. The newly infected birds could carry the virus down North American flyways. The H5N1 outbreak in poultry and birds has grown in scale, causing massive international government responses, and economic, food, and trade impacts due to the animal disease and public health concerns. In wild populations, avian flu is not typically fatal—or even apparent. To reduce the possibility that highly pathogenic H5N1 enters the United States accidentally or intentionally, the USDA has blocked imports of poultry and poultry products (such as feathers, meat, or eggs) from affected countries, and increased smuggling interdiction efforts. Despite the attention given to migratory bird surveillance in North America, some believe that poultry imports into Central and South America are a more likely pathway for the virus to enter the Western Hemisphere. If the virus spreads from poultry to wild birds, subsequent wild bird migration could bring the virus north into the United States. Fatality rates are high; over 55% of the more than 275 people infected with highly pathogenic H5N1 (mostly in Asia) have died. Officials worry that the virus could mutate or combine with human flu viruses to allow efficient human-to-human transmission, which could lead to a human flu pandemic. If highly pathogenic H5N1 is found in the Americas, it does not signal the onset of a global human pandemic. The virus has not yet mutated to allow human-to-human transmission, and scientists disagree on the likelihood of this happening. Thus, FAO and WHO developed a strategy calling for the swift and coordinated control of avian flu in poultry as the best way to prevent or delay a human pandemic from developing, by reducing the number of animal hosts in which the virus may evolve. As discussed earlier in this report, federal and state agencies have increased surveillance of wild birds for H5N1. In 2006, USDA began a new indemnity plan for low pathogenicity avian flu.
Avian influenza is a viral disease that primarily infects birds, both domestic and wild. Certain strains of bird flu break the avian barrier and have been known to infect other animals and humans. Avian flu viruses are common among wild bird populations, which act as a reservoir for the disease. While rarely fatal in wild birds, avian flu is highly contagious and often fatal in domestic poultry, prompting strict biosecurity measures on farms. International trade restrictions imposed by countries to counter avian flu can have large economic effects.
The H5N1 strain of highly pathogenic avian influenza (HPAI) has spread throughout Asia since 2003, infecting mostly poultry, some wild birds, and a limited number of humans through close domestic poultry-to-human contact. The virus has spread beyond Asia, reaching Europe in 2005 and the Middle East and Africa in 2006. Over 250 million poultry have died or been destroyed internationally. Human mortality among the more than 275 people infected exceeds 55%. Fears that the virus could mutate to allow efficient human-to-human transmission and cause a human pandemic have prompted a massive political and public health response.
Since wild birds can carry the highly pathogenic H5N1 virus, federal, state, and other agencies have increased surveillance of wild and migratory birds. Surveillance is particularly high in Alaska, where Asian and American flyways overlap. Migrating birds from Asia could carry the virus to Alaska and infect birds from the Americas on shared nesting grounds. The newly infected birds could carry the virus down North American flyways. Alternatively, imports into Central and South America could introduce the virus to the Western Hemisphere, and subsequent wild bird migration could bring the virus north into the United States. The United States also has blocked imports of poultry and poultry products from H5N1-infected countries.
The highly pathogenic H5N1 strain has not yet been detected in the United States. But surveillance has detected different, low pathogenicity strains in wild bird populations, including a low pathogenicity H5N1. The low pathogenicity strain does not pose the same threat as highly pathogenic H5N1. Even if highly pathogenic H5N1 is found in the Americas, it does not signal the onset of a global human pandemic. The virus apparently has not yet mutated to allow efficient human-to-human transmission, and scientists disagree whether or when this may happen.
Controlling avian flu in poultry, and to the extent possible in wild birds, is seen as the best way to prevent a human pandemic from developing—by reducing the number of animal hosts in which the virus may evolve. Indemnity payments to compensate farmers for birds destroyed in eradication efforts are seen as an important element of increasing success to control the disease.
Congressional agriculture committees have held hearings on avian influenza preparedness, and appropriators have increased funding for surveillance and other preparedness activities for poultry and wild birds.
This report will be updated periodically.