The Avian Flu: Symptoms and Significance
Posted: Wednesday, July 22, 2009
by Carolyn Tytler
The World Health Organization has recently declared swine flu (H1N1) to be a pandemic. The disease has spread quickly across the globe. Fortunately, thus far it has proven to be a relatively mild infection, with many cases not serious enough to be reported to health authorities. Of those cases reported, only 0.5 per cent have been fatal; that is, only five people have died for every thousand infected. Preparations are well underway for production of a vaccine which will grant immunity to swine flu shortly after the autumn influenza season begins.
The virus is spread through contact with the saliva, nasal secretions or feces of infected birds, or from surfaces which have been contaminated with these secretions. Poultry on farms, such as chickens, turkeys and ducks can be infected from contact with one another or with secretions on the ground or floors and sides of their cages.
Until 1997, it was believed there was a barrier which prevented the transfer of the H5N1 virus from one species to another, so humans were thought to be protected. However, there have been increasing incidences of bird-to-human infection. Because humans have never been infected with this virus before, they have no natural immunity. More than half of those who have caught the H5N1 virus have died.
The incubation period, the time from exposure to the virus to becoming ill, seems to average about seven days. Initial symptoms are likely to be a high temperature, above 38 degrees C., watery diarrhoea, vomiting, abdominal pain, chest pain, and possible bleeding from the nose and gums. Fatigue, muscle aches, coughing and eye infections may also be noted.
Usually, difficulty in breathing develops about five days after the first symptoms. A hoarse voice and a crackling sound when inhaling are frequently observed, and the patient may produce bloody sputum. Almost all patients developed pneumonia which did not respond to antibiotics. The patient's condition deteriorated rapidly and multiple organ failure occurred. Respiratory failure and death took place in more than half the patients from three to thirteen days after the onset of symptoms.
The noticeable symptoms may vary extensively from one patient to the next. Two victims from southern Viet Nam had no respiratory problems at all, but were diagnosed with acute encephalitis (inflammation of the brain). Another from Thailand had fever and diarrhoea, but no respiratory symptoms. The common thread between the three was that they had all been recently in contact with infected poultry.
In the past several years, there has been a limited number of human-to-human transmissions of the virus. This is a cause for concern. Viruses are always capable of mutating. If it becomes easier for the H5N1 virus to pass quickly and easily from one person to another, humanity might be confronted with a pandemic capable of wiping out half the earth's population.
As of July 1, 2009, according to the World Health Organization, there has been 436 recorded cases of Avian Influenza on the planet. Of these, 262 people have died of the illness. Scientists are monitoring the course of this virus very closely. They realize that if it mutates and becomes easily transmitted among humans, the resulting pandemic will make the swine flu episode seem like a Sunday afternoon picnic.
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