[FoRK] Bird flu drug for humans rendered useless
Adam L Beberg
Sat Jun 18 15:16:54 PDT 2005
They saved the chickens, now millions of people can die instead. That's
good because there are way too many people in China, but not enough
chickens to go around. The lesson here is that if you find a new drug
for a possible pandemic, don't tell the Chinese, they are clearly too
dumb to save, and it's not like they pay for things anyway so no profit
The war against the virii is over, we gave them nukes and surrendered.
Bird flu drug for humans rendered useless
China?s use on chickens has led to resistance in virus
By Alan Sipress
The Washington Post
Updated: 11:55 p.m. ET June 17, 2005
HONG KONG - Chinese farmers, acting with the approval and encouragement
of government officials, have tried to suppress major bird flu outbreaks
among chickens with an antiviral drug meant for humans, animal health
experts said. International researchers now conclude that this is why
the drug will no longer protect people in case of a worldwide bird flu
China's use of the drug amantadine, which violated international
livestock guidelines, was widespread years before China acknowledged any
infection of its poultry, according to pharmaceutical company executives
Since January 2004, avian influenza has spread across nine East Asian
countries, devastating poultry flocks and killing at least 54 people in
Cambodia, Thailand and Vietnam, but none in China. World Health
Organization officials warned the virus could easily undergo genetic
changes to create a strain capable of killing tens of millions of people
Although China did not report an avian influenza outbreak until February
2004, executives at Chinese pharmaceutical companies and veterinarians
said farmers were widely using the drug to control the virus in the late
The Chinese Agriculture Ministry approved the production and sale of the
drug for use in chickens, according to officials from the Chinese
pharmaceutical industry and the government, although such use is barred
in the United States and many other countries. Local government
veterinary stations instructed Chinese farmers on how to use the drug
and at times supplied it, animal health experts said.
Amantadine is one of two types of medication for treating human
influenza. But researchers determined last year that the H5N1 bird flu
strain circulating in Vietnam and Thailand, the two countries hardest
hit by the virus, had become resistant, leaving only an alternative drug
that is difficult to produce in large amounts and much less affordable,
especially for developing countries in Southeast Asia.
?It?s definitely an issue?
"It's definitely an issue if there's a pandemic. Amantadine is off the
table," said Richard Webby, an influenza expert at St. Jude Children's
Research Hospital in Memphis.
Health experts outside China previously said they suspected the virus's
resistance to the medicine was linked to drug use at poultry farms but
were unable to confirm the practice inside the country. Influenza
researchers at the U.S. Centers for Disease Control and Prevention, in
particular, have collected information about amantadine use from Chinese
Web sites but have been frustrated in their efforts to learn more on the
China has previously run afoul of international agencies for its
response to public and agricultural health crises, notably the SARS
epidemic that began in 2002. China's health minister was fired after the
government acknowledged it had covered up the extent of the SARS
outbreak by preventing state-run media from reporting about the disease
for months and by minimizing its seriousness.
In interviews, executives at Chinese pharmaceutical companies confirmed
that the drug had been used since the late 1990s, to treat chickens
sickened by bird flu and to prevent healthy ones from catching it.
"Amantadine is widely used in the entire country," said Zhang Libin,
head of the veterinary medicine division of Northeast General
Pharmaceutical Factory in Shenyang. He added, "Many pharmaceutical
factories around China produce amantadine, and farmers can buy it easily
in veterinary medicine stores."
Drug?s price far lower in China
Zhang and other animal health experts said the drug was used by small,
private farms and larger commercial ones. Amantadine sells for about $10
a pound, a fraction of the drug's cost in Europe and the United States,
where its price would be prohibitive for all but human consumption.
Two months before China first reported a bird flu outbreak in poultry to
the World Animal Health Organization in February 2004, officials had
begun a massive campaign to immunize poultry against the virus. They
have now used at least 2.6 billion doses of a vaccine.
But researchers in Hong Kong have reported that the H5N1 flu virus has
been circulating in mainland China for at least eight years and that
Chinese farms suffered major outbreaks in 1997, 2001 and 2003.
Scientists have traced the virus that has devastated farms across
Southeast Asia in the last two years to a strain isolated from a goose
in China's Guangdong province in 1996.
The U.N. Food and Agriculture Organization has long recommended that
countries try to eradicate infectious animal diseases by slaughtering
infected flocks and increasing safety measures on farms. Last year, the
FAO also suggested that countries consider vaccinating their poultry
against bird flu. But the guidelines never recommended the use of
antiviral drugs such as amantadine, which, unlike vaccination, has been
proven to make viruses resistant, officials said.
In 1987, researchers at a U.S. Department of Agriculture laboratory
demonstrated that bird flu viruses developed drug resistance within a
matter of days when infected chickens received amantadine.
Still, a veterinarian with personal knowledge of livestock practices
across China said Chinese farmers responded to the bird flu outbreak by
putting the drug into their chickens' drinking water. The veterinarian
asked that his name not be published because he feared for his livelihood.
Explanation for ?such high resistance levels?
"This would explain why we're seeing such high resistance levels," said
Michael T. Osterholm, director of the Center for Infectious Disease
Research and Policy at the University of Minnesota. While various
antibiotics have lost their effectiveness because of overuse, he said,
the emergence of resistance to amantadine is unprecedented because it is
"This is the first example of an antiviral drug that was used for animal
production that has major implications for human health," Osterholm said.
A popular Chinese handbook, titled Medicine Pamphlet for Animals and
Poultry, provides farmers and livestock officials with specific
prescriptions for amantadine use to treat chickens and ferrets with
respiratory viruses. The manual, written by a professor at the People's
Liberation Army Agriculture and Husbandry University and issued by a
military-owned publishing company, prescribes 0.025 grams of amantadine
for each kilogram of chicken body weight.
Farmers also use the drug to prevent healthy chickens from catching bird
flu, giving it to their poultry about once a month or more often when
the weather is liable to change and chickens are considered susceptible
to illness, veterinary experts said. The antiviral is often mixed with
Chinese herbs, vitamins and other medicine.
In the United States, amantadine was approved in 1976 by the Food and
Drug Administration for treating influenza in adults. Amantadine and it
sister drug, rimantadine, known collectively as amantadines, work by
preventing a flu virus from reproducing itself. Both are now ineffective
against the H5N1 strain.
International health experts stressed that amantadine could have been
vital in stanching the spread of the bird flu virus in the early weeks
of an epidemic.
Now, the only alternative is oseltamivir and closely related zanamivir,
which stop the flu virus from leaving infected cells and attacking new
ones. Oseltamivir is easier to use and has far greater sales.
"Amantadine is the cheapest drug against flu," said Malik Peiris, an
influenza expert at the University of Hong Kong. "It is much more
affordable for many countries of the region. Now, it is clearly no
longer an option."
Special correspondents Ling Jin in Beijing and K.C. Ng in Hong Kong
contributed to this report.
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