- Hello, Jeff - Some strains of HPAI are developing a resistance
to tamiflu the standard treatment for the virus.
-
- I seem to remember Professor Kawaoka whose team was working
on pandemic strain of Spanish Flu calling for drop in BSL level from BSL
4 to BSL 3.
-
- He asserted that because we have "Tamiflu"
(oseltamivir) we can lower the Biosafety level.
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- The situation with Avian Flu A H5N1 strains becoming
resistant to tamiflu should remind us that Influenza can quickly mutate
and we must remember that our known medications cannot be relied upon.
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- Patricia Doyle
-
- WHO Charts Disturbing Changes In Avian Influenza
Virus
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- By Helen Branswell
- Canadian Press - Canada.com
- 5-22-5
-
- The World Health Organization urged countries to make
full haste with pandemic influenza preparations on Wed 18 May 2005, 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
is the case," Fukuda said from Atlanta. Fukuda was part of a recent
3-person WHO mission to Viet Nam, 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 [CIDRAP]
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 in which the virus was partially
resistant to oseltamivir will give public health officials around the world
pause. Oseltamivir (sold as Tamiflu) is one of only 2 antiviral drugs known
to work against H5N1 and is the 1st choice for pandemic planners, because
it is easier to use [can be taken by mouth] 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 specter of a resistant strain of the virus becoming
dominant and spreading among people, creating a situation in which the
world has virtually no therapeutic weapons to combat pandemic flu in the
months before a vaccine could be produced. Hayden noted that human flu
strains resistant to oseltamivir are generally less fit and don't transmit
as well. But Dr. Earl Brown, an influenza virologist at the University
of Ottawa, said oseltamivir is too new a drug for anyone to assume that
pattern will persist across all subtypes of influenza. "The indications
from the lab data are that the virus is sort of a wimpier virus when it's
resistant to the drug," he said. "So if that's always the case,
that's good. But I think, given limited experience with the drug, you can't
be too categorical at this point."
-
- Fukuda said the authors of the report felt the situation
demands close observation. "It's definitely a warning sign that we
need to monitor resistance to oseltamivir," he said. "Clearly,
that's what we have to do." The report also outlined the disturbing
changes in infection patterns in northern Viet Nam, where this spring,
there have been more clusters of cases, clusters that lasted for longer
periods of time, and a greater age range among human cases. The changing
patterns suggest the virus has altered. Among the possibilities is that
the genetic mutations have allowed the virus to be transmitted more easily
to people in the 1st place, or among them after a 1st case occurs. At the
same time, molecular analysis of the virus shows genetic changes near what's
known as the "receptor binding site," the point where the invading
virus attaches to the cell walls of a host.
-
- Influenza viruses comprised entirely of avian influenza
genes don't tend to bind well to human receptor binding sites. But these
changes may indicate the virus is evolving to be a better fit. Still, given
how little is known about influenza, no one can predict with certainty
the implications of these changes.
-
- "The information is pretty sketchy," said Dr.
Frank Plummer, scientific director of Canada's National Microbiology Laboratory
in Winnipeg, which sent a team of 3 scientists to Hanoi on Wednesday [18
May 2005]. "And till we know quite a bit more, it's hard to know whether
these things are real or not." The team, led by Dr. Yan Li, chief
of the influenza laboratory, will help scientists at Viet Nam's National
Institute of Hygiene and Epidemiology analyze blood samples from contacts
of H5N1 cases to determine whether additional undetected infections have
occurred. "It will help a lot in, I think, clarifying the extent of
infection," Plummer said.
-
- --
- ProMED-mail
-
- (Apart from information on the appearance of resistance
to the anti-neuraminidase drug -- oseltamivir --, this report adds little
to previous comments on the WHO Consultation Document
-
- http://www.who.int/csr/disease/avian_influenza/H5N1
%20Intercountry%20Assessment%20final.pdf
-
- which summarized the outcome of the WHO Meeting in Manila
in early May 2005. The risk of a major pandemic of influenza remains unquantifiable.
There have been more apparent clusters of human avian influenza virus infection
in the north of Viet Nam than in the south of Vet Nam or elsewhere, but
in virtually all situations, there has been exposure to or consumption
of diseased chickens. There is still no firm evidence that the H5N1 virus
transmits directly from human-to-human, although this possibility cannot
be excluded. Although the avian influenza viruses isolated from humans
appear to be more heterogenous in terms of the nucleotide sequence of the
hemagglutinin gene (which encodes the virus protein that binds to the virus
receptor on the surface of host cells), it should not be concluded that
the virus may be changing to a form capable of human-to-human transmission.
There is no directionality in virus variation unless there is an external
selective force favoring a particular change. It is possible that a virus
capable of transmission between humans may evolve by chance, but there
is no reason to suppose that such a virus evolving by mutation alone would
be exceptionally virulent, rather the reverse. In the H7N7 avian influenza
outbreak in the Netherlands in 2003, many poultry workers developed mild
infections (conjunctivitis) with very limited spread to household contacts,
but no pandemic ensued. The greatest risk remains the generation of a novel
human pathogen by reassortment of genes between the H5N1 avian virus and
human influenza viruses. - Mod.CP)
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- Patricia A. Doyle, PhD
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- Please visit my "Emerging Diseases" message
board at: http://www.clickitnews.com/ubbthreads/postlist.php?
Cat=&Board=emergingdiseases
- Zhan le Devlesa tai sastimasa
- Go with God and in Good Health
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