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A first-of-its kind study has projected a steep rise in use of antimicrobials in livestock and poultry. The study estimates present global antimicrobial consumption in “food animals” at 63,151 tonnes (± 1,560) and this is projected to rise by 67 per cent to 105,596 (± 3,605) tonnes by 2030.
The study estimates that the global average consumption of antimicrobials stands at 148 mg/kg for chickens. It says that in middle- and low-income countries, rising income level has resulted in an increasing demand for animal protein.
In a bid to meet this demand, countries like Brazil, Russia, India, China and South Africa (BRICS) have shifted towards cost-efficient integrated intensive production systems. These necessitate the use of antimicrobials to keep animals healthy and maintain their productivity.
When asked about the projections, Thomas Van Boeckel, one of the authors of the paper, said, “Although the effect on humans is somewhat indirect, given the huge volume involved and the huge projected surge in consumption in the animal sector, we should be more cautious because this indiscriminate use of antibiotics is a waste of common resource.”
The study has been published in the journal, Proceedings of the National Academy of Sciences, of the United States of America by researchers at Princeton University and the Centre for Disease Dynamics, Economics and Policy. It was released on March 19, 2015.
Method of estimation
It says that there is no quantitative measurement of antimicrobial consumption by livestock and the authors addressed this gap by using statistical models which combine maps of livestock densities, economic projections of demand for meat products and the current estimates of antimicrobial consumption in food animals in high-income countries for 2010 and 2030.
The study mapped antibiotic consumption in 228 countries in food-producing animals. Estimates on antimicrobial consumption for this study were obtained from 32 high-income countries. These data were extrapolated to estimate antimicrobial consumption in intensive production systems in middle- and low-income countries. The underlying assumption for this study is that intensive farming systems are highly standardised and use similar quantities of antimicrobials across high, middle, and low-income countries. It is to be noted that the unregulated use of antimicrobials in the production of food-producing animals is recognised as one of the factors contributing to the development of antimicrobial resistance across the world.
When asked about the basis of the projections, Boeckel said, “The projections are based on maps on livestock densities (segregated between extensive and intensive livestock) produced by International Livestock Research Institute (ILRI) and the Food and Agriculture Organization (FAO). We project the proportion of the production that will be carried out intensively based in the evolution of gross domestic product (GDP) per capita.”
Ramanan Laxminarayan, another author of the paper said, “intensive farming practices can be very different between the US and India with respect to hygiene, nutrition, herd health and genetic potential of the flock. There are wide variations in practices even within India and, therefore, our projections which apply to the entire sector are approximate.”
What is driving consumption
One of the limitations in the analysis, as pointed out in the study, is that it does not evaluate antimicrobial consumption on a compound-specific basis.
The study mentions that rising incomes in transitioning countries is driving antimicrobial consumption and antimicrobial resistance as well. In fast-growing Asian countries, where antimicrobial consumption is projected to increase significantly, it will pose a serious challenge as these countries are currently experiencing the most rapid increase in demand for meat products, but regulations on antimicrobial use is lacking and surveillance information on antimicrobial consumption is either non-existent or is not available to the public.
The study estimates that in Asia, nearly half of the increase in antimicrobial consumption in food animals by 2030 is likely due to the shift in production systems. In addition, antimicrobial consumption in chicken in Asia is expected grow by 129 per cent. China and India were in 2010 the only two Asian countries amongst the top five consumers of antimicrobials across the world and are projected to remain so by 2030 as well. Both China and India are among the top five countries which are projected to show the largest relative increase in antimicrobial consumption in food animals between 2010 and 2030. In addition, the total size of areas where antimicrobial consumption is currently greater than 30 kg/km2 will grow by 143 per cent for chicken in Asia. This is primarily due to the expansion of the poultry sector in India alone where areas of high antimicrobial consumption (above 30 kg/km2) are expected to grow by 312 per cent in 2030.
The study mentions that India is a country contributing to the overall share in the growth of antimicrobial consumption. India is already facing antibiotic overuse in human medicine and a very high prevalence of antibiotic resistant bacteria (about 95 per cent of adults in India carry bacteria resistant to β-lactam antibiotics). Widespread resistance may impact India more as India’s bacterial disease burden is amongst the highest in the world and thus antimicrobials play a crucial role in limiting mortality and morbidity.
Fallout
When asked about the impacts of increased antimicrobial consumption in food animals on the threat of antimicrobial resistance in India, Laxminarayan said, “Antimicrobial use, in both humans and animals, is the evolutionary force that drives resistance. The consequences of this are clear in India where 58,000 newborns die each year due to untreatable bacterial infections. Further increases in antimicrobial use should be avoided when these are not directly contributing to the treatment of sick animals or humans. Reducing antimicrobial use in the animal sector can be accomplished by a ban on pre-mixed antibiotic feed.”
In July, last year, the Centre for Science and Environment (CSE) had released a study revealing the presence of antibiotics in chicken. CSE had also highlighted the indiscriminate use of antibiotics for non-therapeutic purposes such as growth promotion and disease prevention in poultry farms and the absence of regulations in India to control the indiscriminate use of antibiotics.