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Comparative Impact Assessment of Options to Curtail Inessential Antimicrobials On-farm

More than half a century ago, antimicrobial resistance (AMR) had already been observed and recognized as a possible societal problem by Alexander Flemming and Almroth Wright. Since then, however, proper alternatives to antibiotics have not been established. This, together with the extensive (mis)use of antibiotics, set the ground for the spread of AMR, resulting in increasing antimicrobial therapy failure. Conservative estimates show that, every year, AMR cause over 700,000 deaths worldwide, with predictions for 2050 reaching 10 million deaths. Although these estimates vary considerably based on the method used and assumptions made, a plethora of studies show that AMR will rise in the foreseeable future. In many countries, there have been initiatives to establish feasible alternatives to antibiotic use and increase societal awareness, and it soon became apparent that AMR emergence and spread is a complex and multi-faceted process involving also animals and the environment, thereby needing to be tackled with a One Health approach. Studies on the sources and transmission pathways of AMR show that livestock production stands among the biggest contributors. The link between AMU in livestock and AMR in humans is due to resistant bacteria generated by selection pressure of veterinary AMU being transferred to humans through exposure to animals, foods and the environment. The types of antimicrobials used in livestock compared to those used in humans are also not well versed in this issue, as resistance to last-resort antimicrobials for humans like colistin (which is still used in livestock in most European countries, including the Netherlands) is being increasingly found in livestock, and such resistance seems also to be easily transferrable between different bacteria.
Since 2008 in the Netherlands, several independent bodies have been established in order to monitor and set measures for reducing antibiotic use (AMU) on farms with the government imposing 20%, 50% and 70% AMU reductions in livestock in 2011, 2013 and 2015 respectively. By that a remarkable 58.4% reduction in AMU in farm animals has been achieved during the period of 2009 to 2015. Yet, data from 2015 up to now show no decreasing trend, especially in the weaned piglet, broiler and veal calf sectors. Due to the complexity of AMR epidemiology and its mutable drivers in these livestock sectors, identifying scientifically sound solutions for reducing AMU on farm is highly challenging. Some of those solutions include: 1) infection control (i.e. enhanced farm biosecurity and hygiene standards), 2) animal husbandry practices (i.e. enhanced farm management, e.g. low-stock density farming, all-in/all-out production systems, rearing of slow-growing breeds, etc.), 3) vaccination (for bacterial diseases, but also viral diseases often complicated by secondary bacterial infections). Indeed, there is absence of sufficient quantitative evidence for the impact of these interventions on AMU, and even less evidence for their sustainability. Also, part of the challenge is not only this scarcity of data but also that the available data reveal variable effects on farm’s economy and AMU. Providing the right conditions for incentivizing further AMU reduction in Dutch livestock requires an assessment of the potential impact on AMU and associated (negative or positive) financial effects of the available interventions aiming at keeping livestock healthy, on the principle that every infection prevented is an opportunity for no treatment. Policy makers and livestock producers would then be able to consider supporting the implementation of a specific intervention instead of another based on their cost-effectiveness.
The main aim of this project is to quantify the overall and antimicrobial class-specific reductions in veterinary AMU, as well as the associated financial effects (both negative, i.e. costs, and positive, i.e. savings), attributable to the implementation of a number of on-farm interventions aimed at keeping livestock healthy, thereby reducing the need of therapeutic AMU.