Bird Flu: Is a Pandemic Looming in Our Future?
Avian Influenzas: The Viruses
Influenzas, commonly referred to as “the flu,” are contagious diseases caused by influenza viruses, types A, B, or C. Influenza Type A viruses, with varying degrees of virulence, can infect humans, birds, pigs, horses, and other animals. Type B influenza viruses normally infect only humans, but have not caused pandemics (global outbreaks of disease). Type C influenza viruses cause only mild illness in humans.
Influenza A viruses are named by the combination of two proteins, Hemagglutinin (H) and Neuraminidase (N), located on the surface of the virus. There are 15 subtypes of HA and 9 subtypes of NA, presenting the possibility of unique 135 combinations.
- Centers for Disease Control and Prevention. 2005. CDC Resources for Pandemic Flu. Retrieved 5-1-2013, from http://www.cdc.gov/flu/pandemic-resources/.
- Centers for Disease Control and Prevention. 2013. Avian Influenza A (H7N9) Virus. Retrieved 4-29-2013 from http://www.cdc.gov/flu/avianflu/h7n9-virus.htm.
- Centers for Disease Control and Prevention. 2013. Background on Human Infections with other Avian Influenza Viruses. Retrieved 4-29-2013 from http://www.cdc.gov/flu/avianflu/h5n1-human-infections.htm.
- U.S. Department of Health and Human Services. 2005. Flu.gov. Retrieved 5-1-2013, from http://www.flu.gov
- World Health Organization. April, 2011. Avian influenza. Retrieved 5-1-2013 from http://www.who.int/mediacentre/factsheets/avian_influenza/en/index.html.
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