In the 1990s, the European Union made a political decision to phase out the use of antibiotics as growth promoters (AGPs). Denmark – with a pork industry roughly equivalent to the size of the pork herd in Iowa – led the way by instituting a full voluntary ban in 1998, and making it compulsory in 2000.
As there have been proposals in the U.S. Congress that would ban even more uses of antibiotics in animal agriculture, the Danish experience provides an interesting and instructive case study. The results have illustrated how counterproductive a sweeping ban can be, including several clear consequences, including:
- Increased death and disease among animals;
- Greater amounts of antibiotics used to treat animal disease, although overall use has decreased — total use declined by 26 percent between 1998 and 2009, while quantities used for therapeutic purposes increased 223 percent;
- While resistance to some antibiotics has decreased in animals, resistance to other antibiotics has gone up;
- Little evidence exists to suggest that antibiotic resistance in humans has declined, which was the purpose of the ban.
Bottom line: A ban on AGPs in Denmark has not had the intended benefit of reducing antibiotic resistance patterns in humans; it has had the unintended consequence of increasing animal suffering, pain and death.
Each year, the Danish government publishes a report on antibiotic use and resistance patterns, as illustrated in the chart below. Ultimately, comparison of resistance patterns from the Danish data in humans and animals provide no clear correlations.
The full report for 2009 can be found at http://www.danmap.org/pdfFiles/Danmap_2009.pdf.
Antibiotic Use in Denmark, 1990-2009
The Danish Experiment: By the Bacteria
Between 1997 and 2009, resistance to antimicrobials in samples from pigs, pork, poultry and poultry meat declined. However, there were increases in resistance in samples from healthy humans:
- Virginiamycin resistance increased to 54 percent (up from 29 percent)
- Vancomycin resistance increased from 2 percent (up from 0 percent)
- Tetracycline resistance increased from 16 percent (up from 8 percent)
- Resistance to ciprofloxacin increased to three percent between 1997 and 2004, and declined to less than one percent in 2009.
- Resistance to ciprofloxacin among E. coli urine isolates from primary health care increased to 4.3 percent
- This increase is consistent with parallel increases in the use of fluoroquinolones in primary care and hospitals, and inconsistent with the decreased use of fluoroquinolones in food animals
- Tetracycline resistance increased in poultry, pigs and humans
- Ampicillin resistance declined in poultry (from 9 to 0 percent), increased in pigs (from 7 to 27 percent), and increased in humans (from 11 to 45 percent)
- Nalidixic Acid/Ciprofloxacin resistance declined in poultry and pigs, but increased in humans (1 to 4 percent)
- Resistance to ciprofloxacin has varied, starting at one percent in 1997, rising to seven percent in 2001, decreasing to 0 in 2002, and increasing to eight percent in 2005
- Resistance to tetracycline was five percent in 1996 and 2005
- Resistance to erythromycin remained low at zero percent in 2005
- Resistance to ciprofloxacin from domestically acquired cases increased from 12-14 percent in 1997 to 28 percent in 2005
- Resistance to tetracycline from domestically acquired cases increased from 9 percent in 1997 to 25 percent in 2001, 24 percent in 2004, and 16 percent in 2005
- Resistance to erythromycin remained low at 0 percent
Frequently Asked Questions on the Denmark Ban
It has been shown that a ban on growth promoting antibiotics in Denmark led to an increase in the use of therapeutic antibiotics. Is it likely that restrictions on the use of growth promoting antibiotics in the United States will lead to the same trend?
Yes, there is every reason to believe that removing antibiotics from animal feed will cause an increase in disease and mortalities, particularly in young animals. Certainly, there has been a misunderstanding among the public and a negative perception of the value of low-dose uses of antibiotics for growth promotion. These growth-promotion claims were established many years ago when antibiotics were first being used in animal production.
There has not been a new growth promotion indication approved in more than 20 years for any antimicrobial considered medically important for human medicine. While growth promotion indications imply that these uses simply “fatten” the animal, what many veterinarians and researchers believe is that their use functions in maintaining gut health by suppressing bacteria causing subclinical disease. Subclinical infections may not be readily apparent but can affect an animal’s ability to efficiently utilize nutrients to reach its optimal production potential. This was most evident in Denmark when withdrawal of antibiotic growth promoters from pigs resulted in the outbreak of intestinal disease in weanling pigs, leading to increased incidence of scouring with corresponding increases in mortality.
Additional Resources on the Danish Experiment
- Political Bans on Antibiotics are Counterproductive: The European Test Case of Increased Animal Disease, Mixed Human Health Benefit (2006)
- National Pork Board: What Happened When Denmark Banned the Sub-therapeutic Use of Antibiotic Growth Promotants? (2006, Phillips)
- Withdrawal of Growth-promoting Antibiotics in Europe and its Effect in relation to Human Health (2007, Phillips)
- The European Ban on Growth-promoting Antibiotics and Emerging Consequences for Human and Animal health (2003, Casewell et al)