Avian Flu - Special Report on YaleGlobal
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The Next Pandemic? |
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H5N1. This string of numbers and letters - representing a strain of avian influenza,
or bird flu - has the international public health community deeply concerned.
Avian flu is common and often spread by migratory birds. In recent years, sporadic
cases of bird flu have affected poultry. Most ominous is when the virus mutates to affect
humans, as well - and this is what seems to have happened. After people in contact with
infected chicken fell ill in Southeast Asia, the alarm bell began to ring. In May 2005, the
World Health Organization (WHO) reported that 97 humans had contracted the avian flu
since late 2003, and 53 of those infected died - a 53.7 percent fatality rate.
If the virus acquires genetic refinements enabling human-to-human transmission,
the situation may become dire. Many experts predict a worldwide epidemic that could,
in worst case, rival the impact of the HIV/AIDS epidemic. With the ubiquity of modern
air travel, the virus could spread throughout the world in a matter of weeks.
Tragically, such a pandemic holds the potential to intensify the divisions between the
world's rich and poor: While wealthier nations would have access to limited supplies of
vaccines and antiviral drugs, the poor would suffer for lack of treatment. Health officials,
therefore, underscore the importance of preventive measures and preparation, lest the
world see a new pandemic.
In this Special Report, YaleGlobal examines the nature and impact - both current and
potential - of the avian influenza.
What is Avian Influenza?
How is Avian Flu spread?
What is Avian Influenza?
There are several strains of avian influenza, but the H5N1 virus -
which occurs mainly in birds and, less commonly, pigs - poses the greatest
threat to humans. Though bird flu generally does not infect humans, several
cases have been reported since 1997. Because of its unique ability to mutate
rapidly and acquire genes from viruses infecting other animal species, H5N1 is
particularly insidious. According to the US Centers for Disease Control and
Prevention, symptoms range from typical flu-like symptoms (fever, cough, sore
throat and muscle aches) to eye infections, pneumonia, severe respiratory diseases,
and other life-threatening complications.
The Spread of Avian Flu
All viruses, including influenza, must invade living cells in order to
reproduce. If both a human influenza virus and an avian influenza virus
enter the same cell, they may randomly trade genetic material. This
process, known as reassortment, gives rise to new viruses that resemble
both the human and avian strains.
Recent research suggests that the trigger for the 1918 Spanish Flu
pandemic was originally an avian influenza virus. Currently, human-to-human
transmission is not a threat, though given the adaptability of H5N1, such a
genetic mutation could be possible in the future. In some countries in the
region, the virus has been identified in pigs, which according to the journal
Nature, "can harbor both bird and human flu viruses, and act as a 'mixing vessel'
for the emergence of a strain of avian flu that can easily infect humans."
Since humans have not previously developed immunity to the H5N1 virus, a
pandemic could be particularly devastating. And because the virus mutates
so rapidly, it may be quick to develop resistance to treatments. For this reason,
preventive efforts are essential.
Useful Links
World Health Organization
Centers for Disease Control and Prevention
Nature
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