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Avian Influenza

Avian influenza

The term avian influenza or ‘bird flu’ is often used to refer to three different phenomena:

Avian influenza and pandemic influenza are two different things. Pandemic influenza occurs when a new strain of influenza emerges and spreads globally. It is feared that avian influenza might acquire the ability to spread easily among humans and cause a pandemic. More information about avian influenza in birds and humans is given below.

Avian influenza in birds

Avian influenza is a disease caused by avian influenza A viruses. Wild birds carry these viruses naturally in their intestines and may not develop symptoms. However, these influenza viruses may spread between birds species and can make some domestic birds, including chickens, ducks, and turkeys, very sick – and kill them.
Avian influenza viruses that attack domestic poultry are distinguished by the severity of the disease they cause:

  • Low pathogenic form – causes mild symptoms (such as ruffled feathers and reduced egg production). This form may go undetected.
  • Highly pathogenic form – spreads rapidly throughout flocks of poultry and may cause disease that affects multiple internal organs and has been known to kill in 90–100% of all cases, often within 48 hours [2]

Epidemiologists have been closely monitoring a highly pathogenic strain of avian influenza – H5N1 – for about 10 years. Since mid-2003, this virus has caused the largest and most severe outbreaks in poultry on record. [3]

Avian influenza in humans

Most avian influenza viruses are not infectious to humans and, therefore, do not pose a threat to human health. However, during an outbreak of avian influenza among poultry, there is a possible risk to people who have had close contact with diseased birds or surfaces that have been contaminated with their secretions or excretions.
Symptoms of avian influenza may depend on which virus caused the infection. Known symptoms in humans include:

  • typical human influenza-like symptoms (e.g. fever, cough, sore throat, and muscle aches
  • eye infections
  • pneumonia
  • severe respiratory diseases (e.g. acute respiratory distress)
  • other severe and life threatening complications

Should a highly pathogenic avian influenza virus, such as H5N1, mutate and become readily transmittable among humans, a pandemic could occur. The continued spread of the avian influenza strain H5N1 across Eastern Asia and other countries has raised concern among experts, but, so far, the spread from human-to-human has been limited. Epidemiologists are continuing to monitor the evolving situation and identify any clusters of human-to-human transmission of H5N1 quickly, so that health officials can attempt to contain and control the outbreak.

  1. Pan American Health Organization. Avian vs. pandemic flu: understanding the threat (press release). Available here.
  2. Centres for Disease Control and Prevention. Key facts about avian influenza (bird flu) and avian influenza A (H5N1) virus. Available here.
  3. World Health Organization. Ten things you need to know about pandemic influenza. Available here.   
  • "I would describe flu as something that makes you feel very, very ill. You get a headache, aching bones, and are generally fed up"
  • "When I get flu symptoms I feel like a train has run over me"
  • "I felt very sick and, during the first week, I had high temperature. Flu was very different to a cold. I went back to work after two and a half weeks. Then I suffered a setback for another week"
  • "I run a guesthouse; flu would be a real pest for me. I couldn’t cook, I shouldn’t cook, and I wouldn’t cook, so I would need to get a lot of extra help in. It would cost me a lot more money. So flu’s a real problem, a right downturn"
  • "I work on my own and when I can’t work, I have to try not to infect my little children, so they avoid getting the flu as well"
  • "I feel a little numb, like I’m in another dimension. Because in general I have sore throat, headache, I feel all clogged-up. Usually a sensation like I’m floating in the air"
  • "Shivers, sweats, makes you ache. Last time I had flu I was off for two weeks"
  • "I think that I would probably be concerned that I would pass flu onto my children, who might not be able to deal with it as well as I would"
  • "Flu makes you feel like you’ve been hit over the head with a baseball bat. You don’t feel like you can get yourself out of bed as all your energy is drawn from you"
  • "I was incapable of working. It just wasn’t possible at all… and my flu dragged on for more than a week"
  • "I have no strength. It annoys me because I can do nothing, it seems like I’m wasting my time"
  • "Flu’s like being hit by a truck because you feel completely gone. There is no energy left in your body. You are suffering from high temperature. You’re sweating a lot and you feel really unwell"
  • "First of all infinite tiredness, then I feel like sleeping and don’t want to eat"
  • "I felt really miserable because my muscles and my bones were aching. Well, I can hardly describe it, I just felt really awful, absolutely miserable"
  • "It’s like there’s something huge treading on your head, like a deafening noise that destroys the eardrums"
  • "The fever was constantly rising – I immediately measured my temperature as soon as I got home. It was 41°C and it kept rising and I was wondering what’s going on. I was really scared! Everything was hurting and it all happened so fast. Flu came out of the blue"
  • "I always feel like my limbs have iron weights tied to them and I’m going to fall over any minute, a really stuffy runny nose and feel antisocial"
  • "I was totally dependent on others! I was incapable of doing anything at all"
  • "The real flu knocks you for six – you just don’t want to move or do anything. It’s not very nice"
  • "Not being able to go to work. Not being able to do the things I have to do at home and the commitments that I have day by day"