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Bird flu has evolved into two strains: researchers
CTV.ca News Staff
Scientists have released ominous news about the deadly H5N1 strain of avian flu.
Researchers say the virus has mutated and is now found in two distinct forms -- raising concerns about human infection and complicating the search for an effective vaccine.
"As the virus continues its geographic expansion, it is also undergoing genetic diversity expansion," Rebecca Garten of the U.S. Centers for Disease Control and Prevention (CDC) said at an infectious diseases conference in Atlanta.
"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 research team found that one of the strains caused the disease in people in Vietnam, Cambodia and Thailand in 2003 and 2004. The second strain infected people in Indonesia in 2005.
The team says the two strains are genetically distinct, although they may come from the same ancestor.
Dr. Nancy Cox, chief of the CDC's influenza branch, stressed that neither of the strains can pass easily from human to human.
But influenza viruses can easily mutate, and scientists have always feared the deadly strain could evolve into a form that would trigger a pandemic, causing millions of deaths worldwide.
U.S. authorities are working on vaccines to combat both H5N1 strains, but the development of a vaccine is dependent on identifying the precise form of a pandemic virus.
Dr. Todd Weber, co-chair of the International Conference on Emerging Infectious Diseases in Atlanta, told CTV Newsnet that scientists are making progress.
He says scientists at the conference are benefiting from the many presentations and insights provided from different countries into what's happening in both domestic poultry and migratory birds -- and how to improve research, response and prevention of an H5N1 outbreak.
"I think more can be done. I think we're all aware of that," said Weber.
"But we're well on the way to ensuring there's good communication, that plans are made to take care of people who are sick and prevent people from getting sick and of course, there's work going on to produce a vaccine."
Weber said people shouldn't forget that basic hand washing is the number one defence to avoid exposure to viruses.
"I'm not sure we're all as good at it as we think we are," said Weber, adding "there are lots of other things being investigated to try to improve people's ability to avoid contamination -- or avoid exposure to viruses should it arrive."
Meanwhile, the Bush administration is warning that bird flu is likely to arrive this year in the U.S., with the increased testing of tens of thousands of wild birds expected to reveal dozens of suspected cases.
A government plan finalized on Monday reveals that officials will test between 75,000 to 100,000 wild birds in 2006 -- nearly six times the number of birds screened since 1998.
The government also plans to quarantine and destroy any poultry flocks where the virus appears.
Interior Secretary Gale Norton said the wild bird testing could reveal 20 to 100 suspected cases of bird flu, although follow-up testing is likely to reveal that "dozens" are false alarms.
Alaska and other spots along the Pacific flyway -- a common route that migratory birds follow into the U.S. -- will be the focus of the testing. The government said tests will also be run on 50,000 water and bird dropping samples from waterfowl habitats.
CTV.ca News Staff
Scientists have released ominous news about the deadly H5N1 strain of avian flu.
Researchers say the virus has mutated and is now found in two distinct forms -- raising concerns about human infection and complicating the search for an effective vaccine.
"As the virus continues its geographic expansion, it is also undergoing genetic diversity expansion," Rebecca Garten of the U.S. Centers for Disease Control and Prevention (CDC) said at an infectious diseases conference in Atlanta.
"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 research team found that one of the strains caused the disease in people in Vietnam, Cambodia and Thailand in 2003 and 2004. The second strain infected people in Indonesia in 2005.
The team says the two strains are genetically distinct, although they may come from the same ancestor.
Dr. Nancy Cox, chief of the CDC's influenza branch, stressed that neither of the strains can pass easily from human to human.
But influenza viruses can easily mutate, and scientists have always feared the deadly strain could evolve into a form that would trigger a pandemic, causing millions of deaths worldwide.
U.S. authorities are working on vaccines to combat both H5N1 strains, but the development of a vaccine is dependent on identifying the precise form of a pandemic virus.
Dr. Todd Weber, co-chair of the International Conference on Emerging Infectious Diseases in Atlanta, told CTV Newsnet that scientists are making progress.
He says scientists at the conference are benefiting from the many presentations and insights provided from different countries into what's happening in both domestic poultry and migratory birds -- and how to improve research, response and prevention of an H5N1 outbreak.
"I think more can be done. I think we're all aware of that," said Weber.
"But we're well on the way to ensuring there's good communication, that plans are made to take care of people who are sick and prevent people from getting sick and of course, there's work going on to produce a vaccine."
Weber said people shouldn't forget that basic hand washing is the number one defence to avoid exposure to viruses.
"I'm not sure we're all as good at it as we think we are," said Weber, adding "there are lots of other things being investigated to try to improve people's ability to avoid contamination -- or avoid exposure to viruses should it arrive."
Meanwhile, the Bush administration is warning that bird flu is likely to arrive this year in the U.S., with the increased testing of tens of thousands of wild birds expected to reveal dozens of suspected cases.
A government plan finalized on Monday reveals that officials will test between 75,000 to 100,000 wild birds in 2006 -- nearly six times the number of birds screened since 1998.
The government also plans to quarantine and destroy any poultry flocks where the virus appears.
Interior Secretary Gale Norton said the wild bird testing could reveal 20 to 100 suspected cases of bird flu, although follow-up testing is likely to reveal that "dozens" are false alarms.
Alaska and other spots along the Pacific flyway -- a common route that migratory birds follow into the U.S. -- will be the focus of the testing. The government said tests will also be run on 50,000 water and bird dropping samples from waterfowl habitats.
