Widespread Use Of Tamiflu May Help H5N1 Become More Deadly, Infectious

The short version : Tamiflu passes through humans and into sewerage and water systems. Scientists are now concerned that Tamiflu could then leach back into areas where migrating birds sometimes gather and give the H5N1 virus more opportunity to meet its 'front line attacker' and learn how to beat it.

From news.com.au :

Tamiflu - the frontline weapon in any bird-flu pandemic - cannot be broken down by sewage systems and could help the virus mutate dangerously into a drug-resistant strain, Swedish scientists say.

Scientists led by Jerker Fick, a chemist at Umea University, tested the survivability of the Tamiflu molecule in water drawn from three phases in a typical sewage system.

The first was raw sewage water; the second was water that had been filtered and treated with chemicals; the third was water from "activated sludge," in which microbes are used to digest waste material.

Tamiflu's active ingredient survived all three processes, which means that it is released in the waste water leaving the plant.

The finding is important because of the risk that Tamiflu, if overprescribed, could end up in the wild in concentrations high enough to let H5N1 adapt to this key drug, the authors say.

Flu viruses are common among waterfowl, especially dabbling ducks such as mallards which often forage for food near sewage outlets.

"The biggest threat is that resistance will become common among low pathogenic influenza viruses carried by wild ducks," said co-author Bjoern Olsen, professor of infectious diseases at the University of Uppsala and University of Kalmar.

These avian viruses could then recombinate with ordinary human flu viruses, creating new strains that are resistant to Tamiflu, he said.

The story also includes interesting use from Japan about the long-term effects of using Tamiflu to fight the yearly round of influenza outbreaks. During the 2004-2005 influenza 'season' in Japan some 16 million fell ill. Six million were treated with Tamiflu.

The Japanese are now showing some of the highest rates of an "emerging resistance" to Tamiflu anywhere in the world.

Has Indonesia's H5N1 Strain Become Resistant To Tamiflu?

For many countries of the world, Tamiflu is their one and only true medical defence against the H5N1 virus. Hundreds of millions of Tamiflu pill courses have been stockpiled, and countries like Australia have supplies ready to be flown into the H5N1 "hot zone" Indonesia within 24 hours, if needed.

But an Australian researcher claims the Indonesian H5N1 virus is not as susceptiable to Tamiflu as it once was :

Jennifer McKimm-Breschkin says laboratory testing shows the viruses from Indonesia are 20 to 30 times less susceptible to the drug as compared to H5N1 viruses that circulated in Cambodia a couple of years ago.

...she says they may help to explain the high death toll from H5N1 in Indonesia, where 80 of 100 patients have died of the disease.