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article imageUpdate: New bird flu strain raises concern for pandemic

By Kathleen Blanchard     Apr 12, 2013 in Health
Bird flu in China has researchers concerned about the possibility of global spread. Scientists who performed a genetic analysis of the strain say there are signs the mutated Avian flu has pandemic potential.
According to the study, the new influenza A virus, H7N9, has never before been seen in humans.
Researchers Masato Tashiro of the Influenza Virus Research Center, National Institute of Infectious Diseases, and Yoshihiro Kawaoka of the University of Wisconsin-Madison and the University of Tokyo collaborated for the study.
Kawaoka, who is an Avian flu expert, explains the virus has a protein mutation that allows it to grow efficiently at temperatures found in human respiratory tract that is higher than that of birds.
Information for the study of the genetic sequencing of the new form of Avian bird flu was taken from databases stored by Chinese researchers.
The new virus has killed 9 people and infected at least 33.
Kawaoka says though it is too soon to predict a pandemic, there are “unmistakable” signs that it is possible.
The researcher explained in a press release:
"These viruses possess several characteristic features of mammalian influenza viruses, which likely contribute to their ability to infect humans and raise concerns regarding their pandemic potential."
Dr. Timothy Uyeki and Dr. Nancy Cox of the influenza division at the Centers for Disease Control and Prevention wrote in a companion article that it “is possible that these severely ill patients represent the tip of the iceberg."
The concern is that there may be many more cases lurking that are undetected in people who are yet to show symptoms.
Concerns are compounded by lack of effective vaccines that may take months to develop.
Symptoms include pneumonia and rapid progression to sepsis which is a widespread infection of the bloodstream.
Two mutations were identified that make the new strain of Avian flu worrisome. The first is a mutation in the surface protein hemagglutinin that the virus uses in both birds and humans to attach to its host.
The other mutation allows the virus to thrive in lower temperatures found in the human respiratory tract where the same mutation helps H7N9 efficiently replicate to cause severe illness.
The nose and throat are the areas where the virus takes hold in humans. So far, the virus has not spread outside of China, but infectious disease experts urge vigilance from health care providers treating travelers especially.
"The coming weeks will reveal whether the epidemiology reflects only a widespread zoonosis, whether an H7N9 pandemic is beginning, or something in between," Drs. Uyeki and Cox concluded.
The researchers also tested the bird flu’s susceptibility to a common class of antiviral drugs known as ion channel inhibitors to find it had no effect on the virus. The scientists say the drug oseltamivir might treat the new Avian H7N9 flu strain that is being watched closely for its potential to spread globally.
Update 4/13/2013: ABC News reports H7N9 Avian flu has now infected a 7-year old whose parents work with poultry. The infected child is hundreds of miles away from the original bird flu outbreak site.
Experts say aggressive action is needed. Should the virus develop the ability to spread from human to human, a pandemic would be imminent.
Dr. Richard Besser, former director of the Center's for Disease Control, U.S., said no one knows if the virus will grow into 'something big', but 'you only get one chance to knock it down."
Virologists report Avian flu is on its way to being able to spread from human to human, Besser said.
Birds are not being sickened by the virus. Tracking the extent of the new Avian flu strain would mean widespread testing of healthy birds in China, Besser explains.
More about Avian flu, H7N9 pandemic, NEJM study, Kowaoka
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