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Use of antibiotics in livestock projected to soar, raising serious health concerns

REUTERS/John Gress
Evidence strongly suggests that a major factor in the spread of drug-resistant pathogens is the common practice of feeding low doses of antibiotics to lifestock to promote their growth.

In recent years, public health officials here in the United States and around the world have been issuing increasingly dire warnings that we may be entering a “post-antibiotic” era, in which common infections and minor injuries — ones we’ve treated successfully for decades with various antibiotic drugs — will once again prove deadly.

As I’ve noted here before, drug-resistant cases of gonorrhea — a disease that infects more than 1 million people globally each day — have surfaced in 10 countries, including Canada, Sweden, South Africa and the United Kingdom. And drug-resistant cases of tuberculosis have now been identified in 92 countries, including the United States.

In some parts of the world, more than half of all diagnosed urinary tract infections are resistant to fluoroquinolones, the antibiotic drug most commonly used to treat the condition.

In the U.S. alone, 2 million people become infected with antibiotic-resistance bacteria each year, and about 23,000 die as a direct result of those infections, according to the Centers for Disease Control and Prevention.

“Effective antibiotics have been one of the pillars allowing us to live longer, live healthier, and benefit from modern medicine,” said Dr. Keiji Fukuda, the assistant director-general for health security at the World Health Organization, last spring, when yet another report was issued on the problem. “Unless we take significant actions to improve efforts to prevent infections and also change how we produce, prescribe and use antibiotics, the world will lose more and more of these global public health goods and the implications will be devastating.”

Evidence strongly suggests that a major factor in the spread of drug-resistant pathogens is the common practice of feeding low doses of antibiotics to lifestock to promote their growth. Some efforts have been undertaken around the world recently to curb this practice. In 2013, for example, the U.S. Food and Drug Administration issued regulations regarding the use of antibiotics on industrial animal feedlots. But those regulations are voluntary, a factor that even the FDA acknowledges limits their effectiveness.

A dangerous trend

Against that background, the findings of a study published last week in the Proceedings of the National Academy of Sciences are particularly worrisome. The study offers the first global look at the use of antibiotics in livestock production.

What it found is far from reassuring. After mapping the use of antibiotics in livestock in 228 countries, the authors of the study estimate — conservatively — that some 63,000 tons of the drugs were fed to chicken, pigs and cattle in 2010. That’s twice the amount of antibiotics used that year to treat people. (In the U.S., livestock consume about 80 percent of the antibiotics purchased each year.) 

But the projected future demand for antibiotics makes even that huge annual tonnage of drugs look small. Using statistical modeling, the researchers estimate that the global use of antibiotics on livestock will increase by a staggering 67 percent over the next 15 years, and in some countries — Brazil, Russia, India, China and South Africa — the use will almost double.

According to the researchers, the rise will be driven mostly (66 percent) by more animals (particularly chicken and pork) being raised for food — a response to the already growing consumer demand for meat in developing and middle-income countries.  The rest of the rise (34 percent) will be triggered by a global shift (also already in progress) to large-scale industrial farms, where antibiotics are used routinely.

An unequal burden

As study co-author Tim Robinson, a scientist with the International Livestock Research Institute, told Reuters reporter Chris Arsenault, “poor livestock producers aren’t responsible for this problem. It’s the big firms rushing to meet the demand in growing cities.”

But, as Robinson also told Arsenault, poor people will be most affected when bacteria resistant to antibiotic medications begins to infect humans more often.

Not only are the poor more susceptible to antibiotic-resistant infections, they are less able to access the medical care needed to fight such infections.

Robinson and his co-authors call for “urgent and concerted action in all countries” to “limit the overuse and abuse of antimicrobials in food production.” Those actions include better surveillance of the use of antibiotics in food animals and the “ultimate phasing out of antimicrobial use for growth promotion” in livestock.

You’ll find an abstract of the study on the PNAS website.

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