Top bird flu scientist warns against antiviral abuse
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A top scientist warned on Thursday against misusing oseltamivir, the antiviral drug that governments are stockpiling to fight a possible human pandemic caused by the H5N1 bird flu, saying that could lead to resistance.
The warning from microbiologist Yi Guan, from the University of Hong Kong, comes after The Lancet medical journal published two research papers that showed resistance to anti-flu drugs had risen by 12 percent worldwide in the past decade.
In some countries in Asia, such as China, drug resistance exceeded 70 percent, suggesting that drugs like amantadine and rimantadine will probably no longer be effective for treatment or as a preventive in a pandemic outbreak of flu.
Guan described that as a tremendous blow because amantadine, a far cheaper drug than oseltamivir, helped control the H5N1 in Hong Kong where it made the first known jump to humans in 1997.
That year, the disease killed six out of 18 people. But by 2003, when the disease began spreading in parts of southeast Asia, amantadine was no longer as effective, Guan said.
Guan said the prudent use of oseltamivir, which is known by its brand name Tamiflu, was of utmost importance if the world wanted to preserve it for a H5N1 pandemic.
“We have to be very careful right now. We don’t want a lot of drug resistance for Tamiflu because if the pandemic comes, it may become useless ... we will then be completely disarmed. We will be finished, this is the concern,” said Guan, who has been studying the H5N1 strain since 1997.
Although some experts say another antiviral, zanamivir, may be effective in controlling H5N1 in humans, the World Health Organization has recommended that governments stockpile oseltamivir—although its high price tag has made it too expensive for poorer nations.
Indonesia, for example, has only 10,000 oseltamivir tablets, or just a course each for 1,000 people. Alarm is spreading in the populous country after the disease killed four people.
Eleven people are now under observation in Jakarta, and officials are awaiting laboratory results to confirm if the virus killed two others, both children.
Experts’ greatest fear now is that the H5N1 virus, which has the power to kill one out of every two people in infects, could set off a pandemic if it gains the ability to be passed easily among people. While they say the virus could have passed in a few cases from person to person who had had very close and sustained contact in the last two years, it has yet to mutate into a form that would allow it to do that easily.
Guan said amantadine would have been a good option to help control the H5N1, had viruses not become resistant to it.
“Amantadine is a cheap, commercially available drug and where there is no Tamiflu, this would have been an important option to control the disease. It makes you concerned,” he said.
China-born Guan said there was good reason for the sudden growth in resistance to amantadine in China, where the SARS virus made its first known jump to humans in 2003. SARS went on to infect people in 30 countries, killing about 800 people in all.
“It’s not accidental that resistance is highest in China. Something happened. When SARS happened, everyone went crazy. So people take antivirals now, they think they have bird flu (when they could have just the common flu or cold),” Guan said.
“Amantadine is so resistant in China. Will Tamiflu become like amantadine? I don’t know. If everyone abuses it, then there will be trouble. We have to worry about drug resistance.”
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