Although many scientists have been concerned that the H5N1 bird flu virus may mutate one day and become easily human transmissible, a recent study seems to indicate that it might not spread easily among humans. Researchers from the Centers for Disease Control and Prevention (CDC), USA, tried to combine a common human flu virus with H5N1 and found it does not spread easily.
This could mean that the mutated virus may not be such a giant threat to global human health. You can read about this study in the Proceedings of the National Academy of Sciences, August 2.
Scientists infected ferrets with genetically engineered H5N1 viruses and found that the infected animals did not spread their illness to other healthy ferrets – all the animals were very close to each other. They also found that the ?mutated’ virus was not as virulent as the original H5N1.
(Virulent = Potent, powerful)
The H5N1 bird flu virus strain may one day mutate by exchanging genetic information with a normal human flu virus. It could infect a human who also had the normal human flu and mutate. Dr. Jackie Katz, one of the researchers, said the study was carried out to see what would happen when H5N1 acquired the genetic changes needed for better transmission.
The researchers mixed H5N1 genetic material with other viruses. Ferrets and humans catch and transmit flu in a very similar way, hence, ferrets were used in this study. Ferrets infected with ?mutated’ H5N1 viruses did not pass on the virus to healthy ferrets in the same cage.
This does not mean that a mutated H5N1 will never be dangerous to humans. It just means that the chances of a mutated virus being a serious threat to global public health are smaller than feared. There are 50 possible combinations of the viruses.
The current H5N1 virus can only infect a human deep down in the lungs, not the upper respiratory tract. This has advantages and disadvantages:
Advantage:
— It is more difficult to make someone ill because the virus has to go a long way down. A human has to be exposed to a large cluster of the virus for longer to get ill.
— An infected human who coughs and sneezes will not emit many viruses, because they are deep down in the lungs – that is one of the reasons humans cannot infect other humans easily.
Disadvantage
— A human who has an infection deep down in the lung(s) will not know about it until it has progressed further than a person who has an upper-respiratory infection. This is one of the reasons the human death rate is so high.
For the H5N1 to become more human transmissible will most likely need to mutate so that it infects the upper-respiratory tract. If it manages to do this, the theory goes, it will spread more easily, but will probably not be so deadly.
(Human transmissible = Spreads from human-to-human)
Written by: Christian Nordqvist
Editor: Medical News Today