Though man has made impressive advances in the field of medicine over the last century, we remain vulnerable to a host of diseases, ranging from the common cold to those that can only be characterized as frightening. Influenza pandemics (worldwide) have occurred at various times in the 19th and 20th centuries. Several pandemics have been recorded; the first Asiatic (Russian) occurred in 1889-91 when one million people died. In 1918-19 a second pandemic suspected to have originated in Europe, known as Spanish Influenza, took millions of lives worldwide. Pandemics keep occurring regularly, in 1932-33; 1947-48; 1957, when Asian flu killed 1 to 1.5 million people; and the 1968-69 Hong Kong Flu outbreak, which killed 0.75 to 1 million. The possibility of a new type of pandemic influenza-due to mutated strains of Influenza, particularly H5N1-is nightmarish.
Avian influenza viruses do not normally infect species other than birds and pigs. Migratory aquatic birds, most notably wild ducks, are the natural reservoir of avian influenza viruses that inhabit the intestines of these birds. Infection in domestic poultry is thought to occur due to contact with these aquatic/wild birds. Fifteen subtypes of influenza virus are known to infect birds, providing a large pool of influenza viruses potentially circulating in bird populations.
Avian viruses do not infect humans, but they do tend to exchange genetic material with other influenza viruses infectious to humans and develop into new viral strains. If someone with human influenza is exposed to this avian virus, it would likely transform into a new deadly form that could spread easily from person to person and cause influenza epidemics (or pandemics) that could be even worse than Spanish flu.
Because of their potential to cross the "species barrier," the great fear is that bird flu viruses currently circulating around the globe might mutate, unleashing a new type of flu virus that could prove even more deadly than Spanish flu, as people's immune systems will not be able to fend off this new strain, and a working vaccine is unavailable.
Go To Viral structure and taxonomy
thanks to Deborah Whitman for all of her help with this Discovery
List of Visuals
- Fig. 1. A beautiful wild duck,
one possible reservoir of avian influenza virus
The Humane Society of the United States