H5N1 Has Evolved Into Two Different Forms

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Main Category: Bird Flu / Avian Flu
Also Included In: Infectious Diseases / Bacteria / Viruses;  Veterinary
Article Date: 21 Mar 2006 - 13:00 PDT

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Researchers from the US Centers for Disease Control and Prevention (CDC) have discovered that there are now two different forms of the virulent H5N1 bird flu virus strain. It appears that the new variant evolved last year and has infected humans in Indonesia.

This will make it more difficult to develop an effective vaccine.

The researchers looked at 300 samples taken from birds and humans during 2003 - 2005. Scientists had thought there was only one type of H5N1 strain. However, as the virus spreads geographically it is also undergoing genetic diversity expansion. Dr. Rebecca Garten said "Back in 2003 we only had one genetically distinct population of H5N1 with the potential to cause a human pandemic. Now we have two."

The researchers stressed that neither of the two H5N1 types has the ability to spread easily among humans.

Currently, scientists around the world are working on a vaccine for humans. The problem is we cannot come up with an effective finished product until we know what the finally evolved virus is like, i.e. we have to wait until we know the exact form of the pandemic virus.

In the USA, research is now underway on creating a vaccine to protect from both forms of the H5N1 strain. A vaccine for one form of the virus would also offer some protection against the other, say researchers.

As the H5N1 avian flu virus strain(s) spreads across the world, the chances of a mutation that could develop into a human pandemic grows. In order to mutate into a human-transmissible virus, the H5N1 strain needs to infect a human who is also sick with normal human flu. The bird flu virus can then exchange genetic information with the human flu virus and pick up its ability to spread from human-to-human.

(Virulent = Potent, powerful.)
(Human-transmissible = In this text it means a virus that can spread from human-to-human)
(H5N1 = Is a Bird Flu virus strain. The one that is often fatal when it infects humans)
(Bird Flu = Avian Flu)
(Flu = Influenza)

Written by: Christian Nordqvist
Editor: Medical News Today
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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