How common is avian flu in humans?
Avian influenza viruses circulate among birds worldwide. In addition to the large outbreaks in birds that have occurred in several countries in Asia, smaller outbreaks have been reported in British Columbia, Texas, New Jersey, Maryland, and other locations in North America. It is rare in humans. To date, a number of subtypes (including H5N1, H7N7, H9N2) of the avian influenza virus have been known to cause illness in people, with H5N1 associated with the most serious illness in humans. Since 1997, there have been several outbreaks of avian flu affecting dozens of people; over 30 people have died. The largest outbreak so far occurred in the Netherlands, where 89 people were confirmed to have H7N7 influenza virus infection associated with a poultry outbreak. One person died.
