Maine Frequently Asked Questions on Avian and Pandemic Influenza   [open html - 16KB]

"Bird flu is an infection caused by avian (bird) influenza (flu) viruses, normally a subtype of a type A influenza virus. Occurring naturally among birds, these viruses are often carried by wild birds in their intestines, causing few if any symptoms. However, they can cause some domestic birds, including chickens, to be very ill and even die. Although bird flu viruses do not usually infect humans, occasionally some strains can. Symptoms of bird flu in humans depend on the subtype and strain of bird flu, but can range from conjunctivitis to typical flu-like symptoms to severe respiratory disease and sometimes even death. There are different subtypes of influenza A viruses, based on viral surface proteins. The hemagglutinin or 'HA' protein and the neuraminidase or 'NA' protein are responsible for the 'H' and 'N' designations, respectively. Each combination of HA and NA proteins result in a different subtype. Within each subtype there are different strains. Although all known subtypes can be found in birds, those that are referred to as 'bird flu' viruses are those that are chiefly found in birds. Likewise, when a subtype is referred to as a 'human flu' virus, is it one that occurs widely in humans. There are only three known major influenza A subtypes of human flu viruses - H1N1, H1N2, and H3N2. Within each of these subtypes are often numerous strains."

2005 Maine Center for Disease Control and Prevention
Retrieved From:
Maine Center for Disease Control and Prevention: http://www.maine.gov/dhhs/boh/
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