Tamiflu Swan Song? - Resistance
To Top Anti-H5N1 Drug Feared

By Cynthia Washam

As the WHO has begun warning of the potential for an avian flu pandemic, governments worldwide have been stockpiling Tamiflu (oseltamivir phosphate). Tamiflu minimizes flu symptoms and duration by preventing the virus from escaping the cells it infects. It also reduces the likelihood of spreading the virus. Now British researchers are predicting that heavy use of Tamiflu, as during a pandemic, will expose wild waterfowl to enough of the antiviral agent to foster a resistant strain [
EHP 115:102­106; Singer et al.].

Release and catch. Release of excreted Tamiflu into the environment could create drug-resistant strains of avian flu in wild waterfowl.

The risk that Tamiflu will promote a resistant virus comes from the drug's excreted metabolite, oseltamivir carboxylate (OC), which is in fact the active antiviral. Up to 80% of ingested Tamiflu is excreted as OC in urine and feces. OC withstands degradation through sewage treatment and for several weeks afterward. Birds drinking water from catchments contaminated with OC would ingest the antiviral, which would inhibit nonresistant viruses in the birds' digestive systems while enabling resistant viruses to proliferate. Birds excreting the resistant virus would spread the strain among other waterfowl at the same body of water.

To estimate birds' exposure to OC, Singer and his colleagues examined data on OC's biodegradability along with measurements of wastewater discharges into 16 major catchment areas in the United States and the United Kingdom. They estimated the number of flu cases in an outbreak within each catchment. Among other suppositions, the researchers assumed that all cases were treated with a standard five-day regimen of Tamiflu.

The team calculated that the most vulnerable catchment in the United States is the Lower Colorado, where they predicted OC concentrations high enough to promote Tamiflu resistance in the virus for up to eight weeks. The most vulnerable British catchment would be the Lee catchment in northeast London. Resistant strains could proliferate within a week after pandemic starts in a region, assuming all patients start taking Tamiflu as soon as they develop symptoms. The authors also note that the range of predicted concentrations could have yet-uncharacterized ecotoxicologic effects.

Singer and colleagues call for more detailed modeling of OC water contamination, particularly in Asia, where the virus is most prevalent and human-to-wildfowl contact is more common. They also recommend studies of ways to minimize the release of OC into waterways, which could include biological and chemical pretreatment in the toilet bowl.

From Patricia Doyle, PhD

Hello, Jeff -- Once again Jeff Rense and odd little Patty Doyle were on the cutting edge. We talked - and warned - about this couple months ago on your program.

Just as we saw with antibiotics, we now see for the prescription of antivirals. It seems that once medical practioners get hold of a medication they over prescribe it to death without a thought for consequences.

So many medications are overused. There are far too many meds in the world now, both human and veterinary. I use very little prescription medication when caring for my animals. I don't even keep up with the new ones entering the market almost daily. I had no idea that there were 'doggie diet pills' until I heard about it on radio news. I do know vets have been prescribing anti-depressants for dogs for some time...complete madness.

Of course, these medications will be found in the environment in ever greater concentrations because that is nature. We ingest and we eliminate from our bodies. I am sure that you remember over 10 years ago when major brand vitamins were found, almost undigested, in sluge from porta-potties and in sewage. We can assume the same holds true for antivirals.

The really sad thing is that with antiviral drugs, we now have a change agent to permit viruses to mutate in the environment. Unlike vitamins, antivirals in the environment can cause viruses to become antiviral resistant.

What really scares me is the fact that a scientist, Dr. Kawaoka, who was working with the 1918 flu wanted to drop the BSL down to level 3 because, (quote) we have tamiflu. BSL 4 down to a BSL 3 because we have tamiflu to fight the 1918 flu? Insanity. We also brought this up on the program.

The scientific community has bought into the pharmaceutical PR and the result is going to be mutated viruses that are resistant to any antivirals. We lost our antibiotic advantage by overuse.

I am so pleased that you presented this information early on and you were the first to do so on the radio and in your website. Most other radio hosts would have laughed at me and skipped over the topic.

Score another one for Doyle and Jeff Rense.

Seriously however, I don't see the pharma industry doing anything to eliminate tamiflu in the environment. To do so would mean they must formally alert doctors about over-prescribing...and they must then stop prescribing it. That is not going to happen.

As an example, there is a medical mystery right now in Warwick Rhode Island. How did mycoplasma pneumonae cause death by encephalitis? It usually causes walking pneumonia but in the case in Rhode Island, it has caused death by encphalitis and other cases. Has the bacteria mutated? Has it done so due to antibiotic overuse? There are also meningitis cases in Rhode Island and a different meningitis in New Hampshire and two other New England states.



Patricia A. Doyle DVM, PhD
Bus Admin, Tropical Agricultural Economics
Univ of West Indies


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