Avian Flu in China - Increasing Resistance

Avian Bird Flu has broken out again in China, this time in the Qinghai and Xinjiang provinces, killing migratory birds, ducks and geese. The continued outbreaks are worrisome because of the large numbers of domestic birds in China and because of the potential for the disease to spread via the migration of the birds. The strain of avian flu that has proven lethal across Asia has been traced to the same strain that was isolated in a goose in China in 1996.

The World Health Organization (WHO) has reported 107 incidences of the disease and 54 deaths in humans throughout Asia, and though China has not yet reported any human cases, other animals in China such as pigs have been affected. Furthermore it seems as though the virus is affecting birds that were once resistance to the disease, suggesting that the virus may be mutating to a more resistant and lethal form.

The WHO is now concerned about reports that Chinese farmers are using the the antiviral Amantadine prophalactically for their chickens, putting it in feed and mixing it with herbs and other drugs as if it were a vaccine. This class of antiviral drug is prescribed by doctors to combat influenza (including avian strains) in humans and is not recommended for use as a vaccine, as it is not cost effective and widespread use promotes drug resistance. However the Washington Post reported that the government has been advancing use of the antiviral for chickens over many years:

"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."

According to the Washington Post:

"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."

However the China's Ministry of Agriculture said in a press release that International Herald Tribune such reports were "totally groundless and counter to the facts."

Acquired resistance by microbes is often associated with bacteria and antibiotics, but the widespread use of this antiviral is problematic and suspected to have contributed to its current lack of potency against the virus in humans. The Washington Post reported that in 1987 the U.S. Department of Agriculture laboratory conducted experiments showing that when chickens were given Amantadine "bird flu viruses developed drug resistance within a matter of days". As increased resistance of the virus to this antiviral renders the treatment inaffective the threat of avian flu virus outbreaks or epidemics lingers.

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