ROME, Oct 3 -- Giving farm animals too many antibiotics can stoke resistance to the drugs, and despite countries taking measures to curb their use in agriculture, in populous nations such as China and India antibiotic use on farms is expected to soar.
Farming experts say action is needed - especially as global demand for meat rises - to curb drug resistance.
Infections resistant to antibiotics are the greatest threat to human health, the World Health Organization (WHO) warned last month, and by 2050 some 50 million people a year may be dying of drug resistant infections, according to a major review in 2015.
"Resistance develops when bugs are exposed to antibiotics, and so the more they're exposed the faster the resistance develops," Liz Tayler at WHO said in an interview.
The more antibiotics are given to animals, or people, the more likely drug-resistant bugs will affect people's health, she said.
"Their poo gets into the system, their meat gets into the system, they pee out the antibiotics that go into the water that then humans consume," she said.
As growing and wealthier populations consume more meat, antibiotic use in agriculture is expected to increase by 67 percent between 2010 and 2030, according to the World Bank. In Brazil, China, India, Russia and South Africa, antibiotic use could double in the same period.
Although some countries have made progress in cutting their use in farming, many have a long way to go.
"The fact that the agricultural sector is starting to talk about it and get involved is very encouraging," said Tayler, who is helping develop national action plans on drug resistance.
"But actually implementing things on the ground and going to scale, particularly in poorer countries, is really very slow and very, very worrying," she told the Thomson Reuters Foundation.
Several European countries have significantly cut their use.
The United States, where each year at least 2 million people become infected with resistant bacteria and 23,000 die as a result, has introduced a voluntary ban on the use of medically important antibiotics to promote animal growth.
Fast-food chain McDonald's has stopped serving chicken in the United States which has been treated with antibiotics which are important for human medicine. It plans to roll this out globally by 2027.
Don't cut out antibiotics
Farmers use antibiotics to treat sick animals, and prevent an infection from spreading on a farm. They are also used in intensive farming to speed the growth of animals.
The use of antimicrobials - which include antibiotics used to treat bacterial infections, and other drugs used against parasites, viruses and fungi - is crucial for food safety and quality, says the U.N. Food and Agriculture Organization (FAO).
"(It) is not simply a matter of taking antimicrobials away, because they are vital ... for animal welfare, food safety and security," said Suzanne Eckford, antimicrobial resistance officer at FAO.
But they should not be used as a substitute for good farm hygiene and better ways of managing animals, she said.
Changes needed include better tracking of animals from farm to consumer, regulation of antibiotic use and better hygiene on farms, said Juan Lubroth, chief veterinary officer at FAO.
"If you ask if we're doing enough to diminish the use, I'd say no we're not, because we don't have the systems or research in place to be able to offer possible alternatives," he said.
Research is needed to produce more affordable and quality animal vaccines, develop alternative treatments to antibiotics, and improve diagnostics, he said.
More than half of countries lack strong laws governing the use of antibiotics, according to the World Organisation for Animal Health (OIE).
In many countries, farmers - as well as patients - can buy antibiotics over the counter without a prescription. They can also end up buying cheaper, but ineffective, counterfeit drugs being sold in the street.
Knowledge is king
It took European countries decades to make the changes needed to address the issue, so countries like Burundi, Bolivia or Bhutan cannot be expected to do it overnight, Lubroth said.
The first step is to know where drugs are being used, how much are used, and improve veterinary services in developing countries, said Matthew Stone, OIE's deputy director general.
"Encouraging a worldwide statutory ban is not going to be effective when the veterinary services don't have the basic means of regulating the use of antimicrobials, let alone the ability to regulate for and enforce a ban," he said.
In the meantime the clock is ticking.
Some cheap and - until recently - highly effective antibiotics can no longer be used to treat people in many countries, said WHO's Tayler.
There have even been signs of emerging resistance to the antibiotic colistin which is used as a last resort to save people's lives when all other drugs have failed.
The impact of losing cheap and effective antibiotics for treating people will be felt hardest in developing countries, Tayler said.
"They have more infection sloshing around, less other ways to treat it," she said. "...nearly every country has got more to do".