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Bird Flu: Is a Pandemic Looming in Our Future?

Author(s): Deanne Erdmann, MS, Christopher Burnett, BA, and Nancy Moreno, PhD

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.