Why Bird Flu Is Not A Pandemic
Most people are aware of the threat of bird flu and the
possibility of it creating a pandemic, a worldwide epidemic of
an infectious disease breaking out and affecting a large
geographic region. Although the virus affects an extensive
geographic region, this virus has not yet reached pandemic
proportions.
According to the World Health Organization, in order for a
pandemic to occur, three conditions must be met: the emergence
of a disease new to a population, the agent affects humans and
causes serious illness, and the agent spreads easily and
sustainably among humans.
The first of these three, "the emergence of a disease new to a
population" has occurred. Although bird flu is in no way a new
disease, as it was first identified in the early 1900's, it was
not infectious to humans until the late 1990's. Therefore, this
particular strain has emerged "new to a population", being the
human population, which was previously unaffected by the
disease.
Likewise, the second criterion has been met, "the agent affects
humans and causes serious illness". The virus has infected 131
people and killed 68. Therefore, the severity of the disease is
apparent. H5N1 causes an exaggerated response in cytokines,
hormones that regulate the immune system, therefore, limiting
the effectiveness of the body's ability to fight the infection.
This virus is also partially resistant to other cells of the
immune system, making it especially resilient.
The third condition has not been met, however. At this point,
the virus does not spread easily and sustainably among humans.
Currently, the H5N1 virus is only transmitted from poultry to
humans, and is not able to pass through human contact.
Unfortunately, the virus is mutating and may be able to do so in
future months, increasing the speed and efficiency in which it
spreads.
Human to human transmission has been suspected, though not
confirmed. Several isolated cases in which the cause of
infection was not clear have prompted questions of the virus
being passed through human contact. In particular, cases of
nurses becoming infected after treating patients, children being
infected with no poultry contact, and parents being infected
after treating children with the disease. However, until
confirmation is attainable that the virus has mutated to the
point human transmission is possible, the third criterion will
not be satisfied and H5N1 will not be classified as a pandemic.
Likewise, the fatality rate will also have to increase to change
the classification of bird flu.