The H5N1 avian flu virus has killed 65 people in Asia since late 2003.
Here are some facts about H5N1 avian flu:
What is "Bird Flue" or avian influenza?
Avian influenza, or “bird flu”, is a contagious disease of animals
caused by viruses that normally infect only birds and, less commonly,
pigs. Avian influenza viruses are highly species-specific, but have,
on rare occasions, crossed the species barrier to infect humans.
There 15 strains of flu that affect birds, but the one causing the
amplifying global scare is the H5N1 subtype. It has circulated in
migrating wild birds for years and has spread to poultry flocks,
starting in South-East Asia, spreading to Russia and now reaching
Europe. It is highly lethal to domesticated birds.
How do people become infected?
Direct contact with infected poultry, or surfaces and objects
contaminated by their faeces, is presently considered the main route
of human infection. To date, most human cases have occurred in rural
or periurban areas where many households keep small poultry flocks,
which often roam freely, sometimes entering homes or sharing outdoor
areas where children play. As infected birds shed large quantities of
virus in their faeces, opportunities for exposure to infected
droppings or to environments contaminated by the virus are abundant
under such conditions. Moreover, because many households in Asia
depend on poultry for income and food, many families sell or slaughter
and consume birds when signs of illness appear in a flock, and this
practice has proved difficult to change. Exposure is considered most
likely during slaughter, defeathering, butchering, and preparation of
poultry for cooking. There is no evidence that properly cooked poultry
or eggs can be a source of infection.
Which countries have been
affected by outbreaks in poultry?
From mid-December 2003 through early February 2004, poultry outbreaks
caused by the H5N1 virus were reported in eight Asian nations (listed
in order of reporting): the Republic of Korea, Vietnam, Japan,
Thailand, Cambodia, Laos People’s Democratic Republic, Indonesia, and
China. Most of these countries had never before experienced an
outbreak of highly pathogenic avian influenza in their histories.
In early August 2004, Malaysia reported its first outbreak of H5N1 in
poultry, becoming the ninth Asian nation affected. Russia reported its
first H5N1 outbreak in poultry in late July 2005, followed by reports
of disease in adjacent parts of Kazakhstan in early August. Deaths of
wild birds from highly pathogenic H5N1 were reported in both
countries. Almost simultaneously, Mongolia reported the detection of
H5N1 in dead migratory birds. In October 2005, H5N1 was confirmed in
poultry in Turkey and Romania. Outbreaks in wild and domestic birds
are under investigation elsewhere.
Japan, the Republic of Korea, and Malaysia have announced control of
their poultry outbreaks and are now considered free of the disease. In
the other affected areas, outbreaks are continuing with varying
degrees of severity.
What are the symptoms?
Bird flu in humans causes symptoms that are like human flu, such as
fever, cough, sore throat and muscle aches, conjunctivitis, pneumonia
and other severe respiratory diseases.
At present, H5N1 is not easily transmitted from bird to human. In
other words, a person would have to pick up a lot of virus in order to
be infected. Nor is it easily passed from human to human: there have
been only three suspected cases, in Thailand, Hong Kong and Vietnam,
where this is believed to have happened. The big worry, though, is
that H5N1 could pick up genes from conventional human flu viruses,
making it both highly lethal and highly infectious. Because it would
be a radically new pathogen, no one would have any immunity to it.
No definitive vaccine against the viral threat is available, because
no one knows the precise shape that it will take after mutating to the
feared highly contagious form. Several prototypes are being explored,
but the risk is that they could be only partially effective or even
useless because the virus’ genetic shape will have changed and will
not be recognised by antibodies. If a pandemic does occur, one worry
is about manufacturing capacity and distribution: making enough of the
vaccine and getting it on time and to the right people, without
causing panic or a black market or leaving poor countries helpless.