Bird Flu is also known by the snappy nickname of H5N1. What do those letters and numbers mean? Put simply they represent a means to identify and
differentiate the various Influenza viruses out there
Letters and Numbers:
The H (as in H5) stands hemagglutinin and the N (As in N1) for neuraminidase. These two identifiers are proteins found on the surface of the virus.
Hemagglutinin has 15 different subtypes while neuraminidase has 9 different subtypes. This allows a differentiation between different strains. All
types of Influenza are found in birds and several have the ability to affect humans.
So what the big deal?
Influenza can change itself over time by one of two ways. The first known as
"antigenic drift." Occurs when small changes in the virus occur
over time. As with any recording you almost never get it 100% perfect. If enough of the virus is changed, the antibodies it has produced may not
recognize the drifted virus and thus the body may be prone to being infected again. The other method is known as
"antigenic shift." Antigenic
shift occurs rapidly and marks a major change in the makeup of the virus with new combinations of hemagglutinin and neuraminidase found on the
surface. The body seldom has a defense against this, but it fortunately is a rare occurrence.
Bad Boys From Past Pandemics
1918-19, "Spanish flu," Influenza A H1N1
1957-58, "Asian flu" Influenza A H2N2
1968-69, "Hong Kong" Influenza A H3N2
Material taken from
The CDC's website
[edit on 10/4/05 by FredT]
[edit on 10/4/05 by FredT]
[edit on 10/4/05 by FredT]
