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What is bird flu?
The outbreaks in South Korea, Japan and Vietnam have been
caused by the H5N1 strain of avian influenza viruses. Avian
influenza can range from a mild disease that has only minor
effects to a highly infectious fatal version. It spreads in
the air and in manure.
It can also be transmitted by contaminated feed, water,
equipment and clothing. Clinically normal waterfowl and sea
birds may introduce the virus into flocks. Broken
contaminated eggs may infect chicks in incubators.
Is bird flu harmful to humans?
Human fatalities from avian influenza are very rare and were
unknown before 1997, when six people in Hong Kong died after
being infected with the H5N1 strain.
Early last year, a 33-year-old Hong Kong man contracted the
H5N1 virus and died of pneumonia.
In April 2003, a veterinarian who had been working on a
Dutch farm infected with bird flu became ill with an H7
strain of the disease and died of pneumonia. The vet did not
take medication against avian and human flu. Rules have been
tightened to ensure anyone who comes in contact with
infected farms does so.
Could bird flu become a human
epidemic?
Although avian flu is very infectious in birds, it does not
spread easily among humans.
There is a danger, however, that an avian virus mixes with a
human influenza and forms a new disease. The new virus could
share genetic material from both viruses, being highly
infectious like human flu and dangerously fatal like the
avian variety. Humans would have no natural defense against
it.
How do humans catch bird flu?
Bird flu was thought only to infect birds until the first
human cases were seen in Hong Kong in 1997.
Humans catch the disease through close contact with live
infected birds.
Birds excrete the virus in their droppings, which dry and
become pulverized, and are then inhaled.
Symptoms are similar to other types of flu - fever, malaise,
sore throats and coughs. People can also develop
conjunctivitis.
Researchers are now concerned because scientists studying a
case in Vietnam found the virus can affect all parts of the
body, not just the lungs.
This could mean that many illnesses, and even deaths,
thought to have been caused by something else, may have been
due to the bird flu virus.
But it can't yet be passed from person to person?
For the most part, humans have contracted the virus
following very close contact with sick birds.
There may have been examples of human-to-human transmission,
but so far not in the form which could fuel a pandemic.
A case in Thailand indicated the probable transmission of
the virus from a girl who had the disease to her mother, who
also died.
The girl's aunt, who was also infected, survived the
virus.
UK virology expert Professor John Oxford said these cases
indicated the basic virus could be passed between humans,
and predicted similar small clusters of cases would be seen
again.
It is not the only instance where it has been thought bird
flu has been passed between humans.
In 2004, two sisters died in Vietnam after possibly
contracting bird flu from their brother who had died from an
unidentified respiratory illness.
In a similar case in Hong Kong in 1997, a doctor possibly
caught the disease from a patient with the H5N1 virus - but
it was never conclusively proved.
Avian influenza, or bird flu, is a virus that is highly
contagious among wild birds and often fatal to domesticated
birds and poultry. Symptoms can include typical flu-like
symptoms, like fever, cough, sore throat and muscle aches,
as well as eye infections, pneumonia and severe respiratory
illness
At the same time, bird flu does have the potential to become
a real and very serious public health problem, and there's a
great deal governments can and should be doing to get
prepared. Scientists have long warned that another deadly
flu pandemic is likely, though no one can predict when it
will occur or whether it will involve the H5N1 virus. |
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