Bird flu grows resistant to Tamiflu

Toronto — Researchers in Vietnam have reported two additional cases of H5N1 avian flu infection in which the virus developed resistance to the antiviral drug Tamiflu.

While the findings will likely lead to concern over the future efficacy of the drug — the main weapon in the limited arsenal against pandemic flu — influenza experts were quick to caution against over-interpreting the results.

But they said the findings raise serious concerns about whether the current dosing regime — which is based on experience with regular human flu strains — is adequate to combat the infection caused by this virulent avian strain.

“I ... worry desperately that the timing and dosage of this drug, if it is to be effective, is going to be very different than the current H3N2 (human flu) model,” said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

Research studies are currently being set up in Southeast Asia to try to determine whether higher doses, for longer periods, are needed to treat H5N1 infections.

Should that prove to be the case, governments would face the unwelcome realization that national stockpiles of oseltamivir, or Tamiflu, will not protect as many people as they had anticipated.

The findings also raise questions about the frequency with which resistance will occur with this flu strain and whether resistant viruses, once they arise, will be able to transmit and spread in the way antibiotic-resistant bacteria do.

Dr. Keiji Fukuda, an influenza expert with the World Health Organization, listed some of the questions posed by the findings, published Thursday in the New England Journal of Medicine.

“How frequently will we see resistance arise? What is going to be the full impact of that? Is that just going to be on individual patients who are under treatment or is it going to escalate and become a larger problem for other people who may get infected by antiviral-resistant viruses?” asked Dr. Fukuda, who was not involved in the research.

Researchers from Oxford University's clinical research unit at the Hospital for Tropical Medicine in Ho Chi Minh City reported the cases, which occurred in January. The two patients, both of whom died, were part of a group of eight patients described in a report to the journal. The other six survived.

The journal also published a related commentary urging physicians not to prescribe Tamiflu for people who want it to stockpile against a potential pandemic.

Drs. Allan Brett and Abigail Zuger argued that personal stockpiling exhausts limited supplies of the drug meant for the treatment of people with human flu and could lead to a rise in resistance if people take the drug inappropriately.

As well, without the guidance of a physician, people could end up taking the drug when they don't actually have flu, they argued.

“It seems to me ... that the potential for it to be used wrongly is just so great because of all the different ways one could use it, because of people's wanting to take a pill the first time they have any kind of flu and so forth, that it would just be a colossal waste, I think,” Dr. Brett, an internal medicine specialist and professor of medicine at the University of South Carolina, said in an interview.

Wonderful. All the hype about Tamiflu and all that seems to be happening from using it is causing the virus to evolve into a resistant strain. So not only do we have to worry about the virus mutating into a human-to-human transmittable form, we also have to worry that this form may also be resistant to anti-viral drugs, too. We need to get a crack vaccine discovery/manufacturing/distribution system ready to respond on a moment's notice.

The drug that will fight the human viral pandemic hasn't been invented yet because the current virus hasn't yet mutated to human receptor form.

I nunderstand that problem. That's why there needs to be a system established that can rapidly get a vaccine developed and mass produced quickly. There has to be a better way than using chicken eggs and in a 6 month process. Seems some NIH grant mioney needs to be targeted in that direction.

3 posted on 12/22/2005 11:42:19 AM PST by doc30 (Democrats are to morals what and Etch-A-Sketch is to Art.)

There has to be a better way than using chicken eggs and in a 6 month process.

I'm not in this field so I don't know if they can assembly line-it up to a point then fine-tune when they know the correct genetic sequences.

Probably not.

"There has to be a better way than using chicken eggs and in a 6 month process."

I read something about coating gold particles with viral DNA somewhere a few months back, so I Googled it, and came up with this:

http://www.powdermed.com/release0710.htm

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