The Expected Outcomes and the Unintended Consequences for Human and Animal Health due to the banning of growth promoting antibiotics in the EU
Introduction
Regulatory authorities throughout the EU have suspended the use of some antibiotics as growth promoters in animal feed. The controversy surrounding this topic results from the issue of whether the use of antibiotics as growth promoters in animals presents a genuine threat of increased antibiotic resistance in human pathogens, and therefore a risk to human health. Supporters of the ban point to falling rates of resistance in animal and human isolates as a direct result of the ban (World Health Organization, 2003). Critics however question whether there is actual evidence supporting a link between the use of growth promoters and resistance in human pathogens and talk about a decline in animal health among the undesirable effects.
In 1986 Sweden implemented a ban on all growth-promoting antibiotics in food animals(World Health Organization, 2003). This was followed by Denmark, in 1995, banning the use of avoparcin and virginiamycin and the European Union (EU), in 1999, banning the use of four remaining antibiotics used for growth promotion ; bacitracin, spiramycin and tylosin, and virginiamycin (World Health Organization, 2003). The motivation behind these bans is thought to be a combination of both consumer and political opinion, in addition to scientific concerns that antimicrobial resistance in animals may be transmissible to humans.
Expected Outcome
Benefits to Human Health
The EU ban has succeeded in the complete removal of the antibiotics previously used as growth promoters which was the main goal of the ban. For example where Denmark previously used in excess of 105 metric tonnes of antibiotics for growth promotion in 1996, in 2000 the use of antibiotics for growth promotion fell to 0 metric tonnes (Danish Integrated Antimicrobial Resistance Monitoring and Research Programme, 2001).
There has been data showing the termination of antimicrobial growth promoters in Denmark has dramatically reduced the food animal reservoir of enterococci resistant to these growth promoting antibiotics, and therefore a reduced reservoir of resistance genes that defer antimicrobial resistance to a number of clinically significant antimicrobial agents in human medicine (World Health Organization, 2003). There are also some signs that the termination of antimicrobial growth promoters in Denmark may be associated with a decline in the prevalence of streptogramin resistance among E. faecium from humans (World Health Organization, 2003).
Unintended Consequences
Animal Health
The ban on these antibiotics originally used for growth promotion has revealed that these antibiotics were important in the prevention of many infections in food animals. It could even be said that the decrease in the resistance pool in animal and human microorganisms has had the cost of a decrease in animal health and consequently animal welfare. Denmark has already reported an increase in both the morbidity and mortality among the swine population (Wegener, 2002) . Most of these have been associated with enteric infections (Verner et al., 2002). Reduced weight gain and frequent bouts of diarrhoea have been seen in 11 percent of finishing pigs and most of the recurring problems of chronic infections in weanling and post weaning pigs are due to Lawsonia intracellularis (Callesen, J., 2002; Verner et al., 2002).
The poultry industry in Denmark has also experienced problems due to the withdrawl of antibiotics, in particular bacitracin (Wicker et al., 1977). One example is the emergence of clostridial necrotic enteritis, which had been previously shown to be suppressed by bacitracin, which is requiring producers to use antibiotics in a therapeutic capacity (Tornee, 2002).
Increased use of Therapeutic Antibiotics in Food Animals
There has been a significant increase in therapeutic antibiotic use due to an increase in infections in food animals since the ban was implemented (Muirhead, S. 2002). After the ban of antibiotics as growth promoters an increase in sales of therapeutic antibiotics rose from 383 tones in 1999 to 437 tones in 2000 (Veterinary Medicines Directorate, 2002). The 7 percent increase in therapeutic antibiotic sales in the swine industry has been attributed by critics to the EU ban as well as to the presence of diseases such as porcine dermatitis and post weaning multi-systemic wasting syndrome (Veterinary Medicines Directorate, 2002). In Denmark alone there has been an increase from 48 to 94 tones in the period between 1996 and 2001 (Veterinary Medicines Directorate, 2002). This increase in therapeutic antibiotic usage has occurred in spite of efforts to improve other critical aspects of animal husbandry to make up for the loss of the growth promoters (The National Committee for Pig Production, 2002).
Conclusion
A great deal of attention has been paid to antibiotic use in food animals including antimicrobial growth promoters because they have the potential to add to problems with antibiotic resistance in humans. Antibiotic resistance is undesirable in any situation including animal husbandry because it has the potential to reduce efficiency and animal productivity (DANMAP, 2009). Knowledge about antimicrobial use in humans must be applied to all settings. Animals require antibiotics for the same reasons humans do and strategies need be put in place to ensure their continued efficacy. This necessitates veterinarians and farmers to unite together with medical professionals to improve the use of antibiotics and subsequently control the spread of antibiotic resistant bacteria (DANMAP, 2009). Antibiotics should be an integral part of disease preventive methods.
References
Callesen, J. 2002. Effects of termination of AGP use on pig welfare and productivity. Page 6 in Abstracts of the International Invitational Symposium: Beyond Antibiotic Growth Promoters in Food Animal Production., Copenhagen, Denmark.
Danish Integrated Antimicrobial Resistance Monitoring and Research Programme. 2001. Consumption of Antimicrobial Agents and Occurrence of Antimicrobial Resistance in Bacteria from Food Animals, Food and Humans in Denmark. Danish Veterinary Laboratory, Copenhagen, Denmark.
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Verner, J. Wheelock. and C. Foster. 2002. Food Safety and Pig Production in Denmark. Report commissioned by the Danish Bacon and Meat Council. Verner Wheelock Associates Ltd, Skipton, UK.
Veterinary Medicines Directorate. 2002. Sales of antimicrobial products used as veterinary medicines, growth promoters and coccidiostats in the UK in 2000. Accessed September 12,2011. http://www.vmd.gov.uk/general/publications/amrrpt2000v51.htm
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D.L. Wicker, W.N. Isgrigg , and J.H. Trammell. 1977. The control of necrotic enteritis in broilers with zinc bacitracin. Poultry Science. 56: 1229–1231.
World Health Organization. Impacts of antimicrobial growth promoter termination in Denmark. 2003. Report number WHO/CDS/CPE/ZFK/2003.1. Accessed September 14, 2011.http://www.keepantibioticsworking.com/new/Library/UploadedFiles/Impacts_of_Antimicrobial_Growth_Promoter_Termi.pdf
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