Researchers discover why avian flu never became a pandemic

Kathleen Blanchard's picture
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Researchers now say the avian flu, or bird flu, is much less likely to cause a pandemic than previously thought. The virus would have to make two mutations simultaneously to become widespread. Last year Avian flu was being closely monitored by the CDC, and the virus received widespread publicity, creating much speculation about how widespread the virus could become.

To date, there have been no sustained human outbreaks of avian flu among humans. Since 2003 the H5N1 strain of bird flu has infected 400 people. New findings from the Imperial College of London suggest that avian flu would be unlikely to cause a pandemic because the virus does not thrive in the temperature of the human nose, and that two genetic mutations would need to happen to the virus at the same time for a pandemic to occur.

Avian flu can infect ciliated cells – cells with little hair-like structures, but cannot infect non-ciliated cells according to the scientists. H5 viruses can only infect cells in the mouth and nose.

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The researchers say the avian flu virus, H5, can only attach to a specific protein called HA and only if it fits that receptor. In order to do that, two genetic mutations of H5N1 flu would have to occur.

Professor Wendy Barclay, corresponding author of the study from the Division of Investigative Science at Imperial College London, said: "H5N1 is a particularly nasty virus, so when humans started to get infected with bird flu, people started to panic. An H5N1 pandemic would be devastating for global health. Thankfully, we haven't yet had a major outbreak, and this has led some people to ask, what happened to bird flu? We wanted to know why the virus hasn't been able to jump from human to human easily.

Scientists continue to work on H5N1 flu vaccine in case avian flu reappears – but according to new research the chances are small. However, the researchers say it is best to remain on guard because “viruses mutate all the time”. The odds of a double mutation that could cause human avian flu pandemic are low. Dr. Barclay says, “Our new findings do not mean that this kind of pandemic could never happen. It's important that scientists keep working on vaccines so that people can be protected if such an event occurs."

The current research has helped scientists understand the avian flu virus better. in the event that a double mutation would occur. According to Professor Ian Jones, leader of the collaborating group at the University of Reading, "It would have been impossible to do this research using mutation of the real H5N1 virus as we could have been creating the very strain we fear.” Instead, the scientists used a model of the human airway to find that avian flu virus would die before it could be widely transmitted among humans, or it would have to mutate twice, and at the same time, to become a pandemic. The findings explain why an avian flu pandemic never happened.

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