(Adds comments from advocacy group, U.S. Department of Agriculture, background)
By Kate Kelland and Tom Polansek
LONDON/CHICAGO, Nov 7 (Reuters) - The World Health Organization urged farmers on Tuesday to stop using antibiotics to promote growth and prevent disease in healthy animals because the practice fuels dangerous drug-resistant superbug infections in people.
Describing a lack of effective antibiotics for humans as "a security threat" on a par with "a sudden and deadly disease outbreak", WHO Director-General Tedros Adhanom Ghebreyesus said "strong and sustained action across all sectors" was vital to turn back the tide of resistance and "keep the world safe".
The WHO "strongly recommends an overall reduction in the use of all classes of medically important antibiotics in food-producing animals, including complete restriction of these antibiotics for growth promotion and disease prevention without diagnosis," the United Nations agency said in a statement.
Any use of antibiotics promotes the development and spread of so-called superbugs, multidrug-resistant infections that can evade the medicines designed to kill them.
According to the WHO's statement, in some countries around 80 percent of total consumption of medically important antibiotics is in the animal sector. They are largely used in healthy animals to stop them getting sick and to speed up their growth.
The WHO said such use should be completely halted.
It said in sick animals, wherever possible, tests should first be conducted to determine the most effective and prudent antibiotic to treat their specific illness.
The WHO's new guidelines "illustrate the degree to which our regulators and large food animal producers are falling short," said Cameron Harsh, a senior manager for the Center for Food Safety, a U.S. advocacy group.
The U.S. Food and Drug Administration has said that medically important antibiotics should not be used for growth promotion in animals.
"The recommendations erroneously conflate disease prevention with growth promotion in animals," Chavonda Jacobs-Young, the U.S. Department of Agriculture's acting chief scientist, said in a statement.
In the United States, Tyson Foods Inc has stopped using antibiotics to produce its retail line of chicken. Perdue Farms, a competitor, said it eliminated the routine use of antibiotics in chicken last year.
Sanderson Farms Inc, the third largest U.S. poultry producer, is the only large U.S. chicken producer that has not made a commitment to limit its use of medically important antibiotics.
The company had no immediate comment on Tuesday. (Reporting by Kate Kellend in London and Tom Polansek in Chicago; Editing by Matthew Mpoke Bigg and Catherine Evans)