Symptoms in humans: Eye infection, cough, fever, sore throat,
muscle aches, headache, pneumonia, acute respiratory distress,
diarrhoea, vomiting and/or nausea.
Worst of the worst outbreak (in poultry): In 2003; 150 million
birds were dead.
First human infection (H5N1 virus): 1997 - in Hong Kong, with a
total of 18 cases, which left six dead.
There were 390 human cases and 246 human deaths of Avian
Influenza A (subtype H5N1) reported to World Health Organization
(WHO) since 2003 up to 12 December 2008.
Even pigs, tigers, leopards, ferrets and domestic cats were the
victims of H5N1 virus.
The latest human case has been reported in Cambodia on 12
December 2008 (as of 15 December 2008).
Avian influenza or more commonly referred as “bird flu”, a viral
infection of animals. Once only confined birds, as the saying
about the viruses goes “viruses that normally infect only birds
and, less commonly, pigs”, the viruses have now found their way
to humans (and other animals).
However, first human infection case surfaced in 1997 in Hong
Kong, while cases in tigers and leopards have been first
reported in December 2003 in Thailand.
Let’s take a look at the root of avian influenza:
The Avian Influenza Viruses in Poultry
Avian influenza infection
among poultry manifests itself into two forms;
low pathogenic form and highly pathogenic form. Poultry
infection of low pathogenic form usually causes mild symptoms
such as the lowered egg productivity or ruffled feathers. The
one that causes the most severe impact is the highly pathogenic
form, that is capable the spread the disease among poultries rather quickly. The virus will affect internal organs, causes disease and mortality within 48 hours.
Migratory Birds and Avian Influenza
Migratory birds are partly responsible for the spread of Avian
influenza viruses are believed to be transmitted to other
poultry when these poultry come into contact with the faeces of
waterfowl. The wild waterfowl are said to have been carrying all
influenza A viruses for centuries without any
sign of harm . These migratory birds have the ability to spread
H5 and H7 viruses to poultry. The virus H5N1, which has caused
panic worldwide in 2003, belongs to H5 subtype. Both H5 and H7
subtypes are originally in low pathogenic form. However, these
viruses are able to mutate into
highly pathogenic form within few months when allowed to circulate in poultry populations. However, the 2003 outbreak has
suggested that some of these wild migratory birds might be
spreading the H5N1 virus in its highly pathogenic form.
The Risk of Infection in Human
According to WHO, H5N1 virus transmission among poultry will put
human health at two main risks:
Direct infection from poultry: Human will be infected by the
virus when they are in direct contact with the infected poultry,
faeces, objects which are polluted by the faeces and other parts
of the infected poultry. Humans who consume infected poultry
which are not properly cooked can contract viral infection. This
infection will cause severe diseases, such as primary viral
pneumonia and multi organ failure, which may lead to death.
Human-to-human infection: The virus may transform its viral
protein coat that and transform into highly infectious form, and
eventually infects human. This adaptation will lead to the
possibility of H5N1 infection from human-human contact (i.e.:
air by coughing and sneezing).
WHO states that avian influenza is now at its in pandemic
alert phase (“phase 3”). This means that there is “no or very
limited human-to human transmission”. Experts also believe that
we are now inching much closer towards another global influenza
pandemic since 1968.
How to Protect Ourselves from Being Infected Regardless of the
alert phase, we should always practice good hygiene and
proper cooking to protect ourselves from being infected. As H5N1
virus has sensitivity towards heat, cooking at minimum 70oC will
definitely destroy the virus (if present). This means that 100%
cooked food will pose no risk of infection.