Posted on 05/18/2005 10:23:31 PM PDT by ex-Texan
TORONTO (CP) - The World Health Organization urged countries to make full haste with pandemic influenza preparations Wednesday as it released a report outlining disturbing changes to the H5N1 virus circulating in Asia.
The report raises concerns that molecular and disease pattern evidence may indicate the virus is becoming more adept at infecting people. It also reveals some strains of the H5N1 virus may be developing resistance to oseltamivir, the drug wealthy nations are flocking to stockpile as fears of a pandemic mount.
An influenza expert who helped draft the report said it's meant to convey the message that the level of anxiety regarding the virus has risen.
"I think it's fair to say that the report signifies a definite step up in concern," said Dr. Keiji Fukuda, a flu specialist from the U.S. Centers for Disease Control who is being seconded to WHO's global influenza program.
The report concedes the authors had limited scientific evidence on which to determine whether H5N1 is becoming an even graver risk to mankind.
"We're basically worried that that's what is happening, but we're also saying that there's not quite enough information available - not quite enough data and cases and patterns to really solidly say that that is the case," Fukuda said from Atlanta.
Fukuda was part of a recent three-person WHO mission to Vietnam, where the alarming changes are being observed in the northern part of the country. His team reported last week to a meeting of international experts in Manila; the report was drawn up from their deliberations.
A leading U.S. epidemiologist said the report contains no single smoking gun to suggest H5N1 is becoming a pandemic strain, but the combined evidence paints a compelling picture that cannot be ignored.
"I think it tells us that everything about H5N1 is headed in the direction that none of us would like to see it go," said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
"Do I say that that's going to mean there's an impending pandemic? I don't know that. Does it tell me that ... there's a growing concern about it? Absolutely."
The report of a case where the virus was partially resistant to oseltamivir will give public health officials around the world pause.
Oseltamivir (sold as Tamiflu) is one of only two antiviral drugs known to work against H5N1 and is the first choice for pandemic planners because it is easier to use than the alternative, zanamivir, which is not licensed in Canada.
Dr. Frederick Hayden, an antiviral expert at the University of Virginia, insisted it wasn't necessarily disturbing to find limited resistance to the drug because it has also been documented in a small percentage of infections with human flu strains.
Still, the finding raises the spectre of a resistant strain of the virus becoming dominant and spreading among people, creating a situation where the world has virtually no therapeutic weapons to combat pandemic flu in the months before a vaccine could be produced.
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Hmm.. Might not be a bad idea for Canada to license zanamivir right about now..
Pro-Med and Recombinomics are full of updates that haven't been posted here as of late. I quit doing it because no one seemed to give a $hit. Marburg is still increasing exponentially. Ebola is loose again. H5N1 is in pigs, dogs, chickens, geese, and is mutating rapidly.
Nothing to see here, move along.
FReepmail me if you want on or off my health and science ping list.
Check this out:
H5N1 Destroys Basic Tenents of Influenza Genetics
Recombinomics Commentary
May 18, 2005
WHO has released details about the genetic changes found in the 2005 H5N1 isolates. The data in the report should destroy the two basic tenets of influenza genetics: drifts via random mutations and shifts via reassortment. Last year WHO press releases offered reassurances that no human genes were found in the latest H5N1 isolates. Since flu contains eight separate genes, reassortment occers when two viruses infect the same cell and the new virus is composed of a constellation of genes derived from both parental sets. This reassortment does not create new genes, it just puts together new combinations of genes.
However, H5N1 has evolved without reassortment with human genes. In 1997 it killed humans in Hong Kong with 8 avian genes. In 2003 it again killed humans in Hong Kong with 8 avian genes. In 2004 it killed humans in Vietnam and Thailand with 8 avian genes. In 2005 it killed humans in Vietnam and Cambodia with 8 avian genes.
For H5N1 to become a true human pandemic virus it needs to transmit human-to-human more efficiently. The H gene drives this transmission. However, swapping H5 for the human H1 or H3 genes would create a H1N1 or H3N1 virus and humans have antibodies to H1 and H3, so it would not be much of a pandemic virus. To create a real pandemic, influenza doesn't swap its H genes, it changes its H gene.
The 1918 pandemic was caused by H1. 1957 pandemic was caused by H2. 1968 pandemic was caused by H3. The 2005 pandemic is caused by H5.
However, H5N1 is going to achieve efficient human-to-human transmission by changing the H5 gene receptor binding domain. Conventional flu genetics rely on random mutations to change genes slowly via genetic drift. The latest WHO update uses the term frequently to describe the small differences between the 2004 and 2005 isolates. This is thought to arise via random mutation created by frequent errors made by the flu replication complex. These random errors cause genetic drift. Errors are made, but they emerge very infrequently. Most of the changes seen in flu isolates on an annual basis are not new errors, but recycled old errors.
The recycled old errors create new genes and the mecchanism is recombination. Thus, the loss of an amino acid in the HA in 2005 H5N1 in northern Vietnam is not a new mutation. It is an old mutation that was identified in 2003 isolates from Hong Kong and Yunan in China and then seen again in 2004 isolates from Yunan and Guangzhou. Although the 2005 bird flu sequences have not been made public, the new 2005 genes are largely generated via recombination because that is how H5N1 and all influenza A viruses evolve..
The new data on the 2005 will show more evolution via recombination. This recombination will be driven by dual infections and the evolution rate will be dependent on the gene pool population and diversity. Because of the large number of asymptomatic infections, the number of dual infections has increased, which has generated more diversity. Thus H5N1 in northern Vietnam is distinct from H5N1 in southern Vietnam, and the isolates in Southeast Asia are distinct from isolates in Indonesia, China, South Korea, and Japan.
The changes are all driven by recombination, which simply recycles old mutations and mixes and matches pieces of genes to create new genes.
H5N1 continues to recombine and evolve as agencies and governments issue press releases on false negatives and other non-events such as the lack of reassortment.
A great deal of time has been wasted on drifts and shifts that play a minor role in influenza rapid evolution.
H5N1 evolves rapidly via recombination which generates drifts and shifts.
Marburg will get attention if it makes it out of Angola. If not, no one much will care.
We care. Who's out there "fixing" these things?
H5N1 is being spread far and wide by birds. The 1918 Spanish Flu kiiled 50 million people; it was also spread by birds. The 1918 flu had a death rate of about 2%. Bird Flu currently kills between 25% and 75% of its victims. Now this news report says that Tamiflu is proving ineffective. Which means that there is no vaccine, no known cure, and no effective treatment for the Bird Flu.
If this deadly flu virus becomes a pandemic in Asia, I'm in favor of cutting off all air travel to that part of the world.
If a deadly flu virus becomes a pandemic nothing will keep it out.
You watch, we won't even have adequate supplies of normal flu vaccine this year. Our wonderful gubmint in action. They've had all the warning possible to head off Bird Flu and nothing will be done.
I wonder what they'll have to say when a few million people are dead? Think they'll fire anyone. Will one congress scum lose his job? Nope.
You and me both, buddy.
You're one of the few keeping up with this pandemic - and it IS A PANDEMIC NOW. When it starts its' sweep, it will be faster than we can imagine. Too bad Tamiflu is no longer usable.
And here's the Pro-Med Mail site: Here.
It might be a devastaing thing to hit Toronto, where all those liberals live, and also were a large Asian population lives as well who travel back and forth bringing this home with them.
Ban all travel to these countries until it's eradicated. It's better than risking a pandemic in North America.
It would be impossible to keep a true flu pandemic out (as opposed to, say, the much less transmissible SARS). You would have to ban all direct physical contact with the rest of the world, and probably still wouldn't succeed.
Thanks backhoe. ;-D
The fatalities in greyhounds this season appear to parallel the deaths in Florida last year, but the scope of the infections is markedly greater this season. Last season dog racing tracks were closed in Florida, but this season the closings are nationwide and the number of fatal infections has increased markedly.Last season H3N8 avian influenza was isolated in Florida. This was the first reported isolation of influenza virus from dogs. H3N8 has been previously associated with equine influenza. There have been H3N8 outbreaks in horses in Florida, Wisconsin, and Kentucky, which may be related to the outbreak in racing dogs.
The widespread nature of this season's outbreak indicates this year's etiological agent is quite infectious. Although the H3 in H3N8 isolates is distinguishable from H3 in human H3N2 isolates, a highly infectious fatal avian influenza that affects mammals is cause for concern. Recent false negatives for H5N1 in Vietnam and WSN/33 H1N1 in Korea raise serious avian influenza monitoring issues.
Testing of the greyhounds for influenza A could answer questions concerning the mysterious deaths of greyhounds throughout the United States.
all kinds of pestilence...
Following a joint research project between the Smithsonian and the Cuban government on the migratory pattern of sea birds there was an outbreak of virus carried by these birds. Speculation was aroused that the Cuban government had used the research to infect a population of birds headed to the US. I have not seen followup on this.
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