A new study predicts the next 15 years will see a startling increase in worldwide use of antibiotics in livestock, raising serious concerns about the effect this will have on a growing global health problem - drug-resistant pathogens or superbugs.
Antibiotics are used widely in the farming of food animals to treat disease and increase productivity. In the US, antibiotic consumption in animals accounts for up to 80% of antibiotic sales.
While studies suggest such practice fuels the spread of drug-resistant pathogens in animals and humans, the lack of reliable global data makes it hard to both measure the size of the problem and come up with solutions.
Now, for the first time, researchers have carried out a broad assessment of antibiotic use in food animals around the world.
In the Proceedings of the National Academy of Sciences, they present their findings in the form of a global map of antibiotic use in livestock, covering a total of 228 countries. Senior study author Dr. Ramanan Laxminarayan, a senior research scholar at the Princeton Environmental Institute at Princeton University, NJ, says:
"The invention of antibiotics was a major public health revolution of the 20th century. Their effectiveness - and the lives of millions of people around the world - are now in danger due to the increasing global problem of antibiotic resistance, which is being driven by antibiotic consumption."
The researchers estimate "conservatively" that the total global consumption of antibiotics by livestock in 2010 was 63,151 tons, and that by 2030, this figure will be 67% larger overall.
They suggest most of the growth (66%) will be due to increases in the number of animals raised for food - driven mostly by rising demand in middle-income countries, and partly (34%) due to a shift toward large-scale, intensive or "factory" farming where antibiotics are used routinely.
In Brazil, China, India, Russia and South Africa the increase will be dramatic, mostly because of these two factors. These five countries will see a 99% increase in antibiotic consumption but only a 13% growth in their human populations over the same period.
Disproportionate effect on millions of poor raising animals without routine antibiotics
Co-author Tim Robinson, Principal Scientist from the International Livestock Research Institute, says the dramatic growth in antibiotic use in animal farming will have a disproportionate effect on millions of poor people who raise their own food animals.
"For about a billion poor people, livestock are essential to survival," he explains. "They are raising their livestock in extensive, backyard systems on the whole and do not use antibiotics as growth promoters or in disease prevention.
"They use them when their livestock are sick and will take a disproportionately high share of the consequences as effective drugs become more costly and less available in treating their livestock and themselves when they become sick."
The study focuses on the farming of cattle, chickens and pigs and pinpoints the latter two as the main consumers of antibiotics in animal food production.
The authors acknowledge that a major limitation of this first global assessment was getting enough reliable data on antibiotic consumption. Their analysis uses data from the veterinary sales of antibiotics in just 32 developed countries.
"An important limiting factor in carrying out this first inventory of antibiotic consumption in animals was the lack of 'modeling-ready' data on veterinary antibiotic sales in many countries," explains lead author Thomas Van Boeckel, a Fulbright research scholar in Princeton's department of ecology and evolutionary biology.
Van Boeckel states that sometimes the difficulty with accessing such information is because of political and legal barriers, but it can also be simply because there are no veterinary monitoring programs.Dr. Laxminarayan concludes:
"Antibiotic resistance is a dangerous and growing global public health threat that isn't showing any signs of slowing down. Our findings advance our understanding of the consequences of the rampant growth of livestock antibiotic use and its effects on human health - a crucial step towards addressing the problem of resistance."
Funds for the study came from a number of sources, including the US Department of Homeland Security, The Organization for Economic Co-operation and Development, the Bill & Melinda Gates Foundation, the RAPIDD Program, and the National Institutes of Health.
Meanwhile, Medical News Today recently learned that treating sewage with chlorine may promote antibiotic resistance. Chlorine - a chemical used widely in water treatment plants - may not be fully blocking drugs and other pharmaceutical compounds from getting into the US water supply. It could also could be creating new antibiotics that are encouraging antibiotic resistance in the micro-organisms in sewage.