Vaccine Resistant H5N1 Bird Flu Spreads In South East Asia

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Main Category: Bird Flu / Avian Flu
Also Included In: Immune System / Vaccines;  Veterinary;  Respiratory / Asthma
Article Date: 31 Oct 2006 - 9:00 PDT

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It emerged in China and is spreading in southeast Asia - a new H5N1 bird flu strain which is highly resistant to current vaccines. The way this virus is evolving means our current measures are probably ineffective, according to Dr. Yi Guan, Director, State Key Laboratory of Emerging Diseases, Hong Kong, in a new report.

You can see the report in the Proceedings of the National Academy of Sciences.

Dr. Guan, and team, say the new strain is gradually becoming the dominant one in south east Asia. They believe the new strain has started a third H5N1 infection wave in southern China, as well as making headway into Hong Kong, Laos, Malaysia, and Thailand. The new strain is taking hold because current vaccines used to protect poultry from H5 infection are much less effective against it.

Several humans have been infected with this new strain, says the report. At the moment it is spreading from rural into urban areas, where efforts to stem its spread will be much more challenging.

The report states that current poultry vaccination methods must be addressed. We cannot rely on a single vaccine over a number of years, as has been the case. Even though the vaccination of all chickens in China is mandatory, the program will not stop the spread of this new strain, which could easily make its way to other parts of the world. If more chickens become infected, so will more humans.

Guan stressed that systemic influenza surveillance of poultry over affected regions must be thorough. "By doing this, we will be able to determine the dynamics of the spread of this virus," he said. "It is also possible that poultry vaccines may need to be tailored to effectively neutralize the particular strain of virus that is present in a particular region."

Several scientists say that thorough surveillance programs will help us eventually come up with a broad-spectrum vaccine - one that may work for many H5 strains.

"Emergence and predominance of an H5N1 influenza variant in China"
G. J. D. Smith , X. H. Fan , J. Wang , K. S. Li , K. Qin , J. X. Zhang , D. Vijaykrishna , C. L. Cheung , K. Huang , J. M. Rayner , J. S. M. Peiris , H. Chen , R. G. Webster , and Y. Guan
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0608157103
Click here to see abstract online

Written by: Christian Nordqvist
Editor: Medical News Today
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