The Hidden Link Between Factory Farms and Human Illness
(Page 3 of 8)
February/March 2009
By Laura Sayre
On a global scale, the situation is even worse. Fifty-five billion chickens are now reared each year worldwide. The global pig inventory is approaching 1 billion, an estimated half of which are raised in confinement. In China and Malaysia, it’s not unheard of for hog facilities to house 20,000 or even 50,000 animals.
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The Mechanics of Resistance
“Concentrated animal feeding operations are comparable to poorly run hospitals, where everyone is given antibiotics, patients lie in unchanged beds, hygiene is nonexistent, infections and re-infections are rife, waste is thrown out the window, and visitors enter and leave at will,” write Johns Hopkins researchers Ellen Silbergeld, Jay Graham and Lance Price in the 2008 Annual Review of Public Health. By concentrating large numbers of animals together, factory farms are terrific incubators for disease. The stress of factory farm conditions weakens animals’ immune systems; ammonia from accumulated waste burns lungs and makes them more susceptible to infection; the lack of sunlight and fresh air — as well as the genetic uniformity of industrial farm animal populations — facilitates the spread of pathogens.
The addition of steady doses of antibiotics to this picture tips the balance from appalling to catastrophic. Poultry producers discovered by accident in the 1940s that feeding tetracycline fermentation byproducts accelerated chickens’ growth. Since then, the use of antibiotics as feed additives has become standard practice across much of the industry. The Union of Concerned Scientists estimates that non-therapeutic animal agriculture use (drugs given to animals even when they are not sick) accounts for 70 percent of total antibiotic consumption in the United States.
The medical community has been cautioning for years against irresponsible antibiotic use among people, but in terms of sheer numbers, livestock use is far more significant. It’s a simple scientific fact that the more antibiotics are used — especially prolonged use at low doses as in factory farms — the more antibiotic-resistant microbes will become. Bacteria and viruses are also notoriously promiscuous, swapping genes across species and even across genera, creating what the Johns Hopkins researchers call “reservoirs of resistance.” “In some pathogens, selection for resistance also results in increased virulence,” they note. In other cases, otherwise harmless microbes can transfer resistance genes to pathogenic species.
There also are indications that factory farm conditions make animals more likely to excrete pathogenic microbes — suggesting another mechanism by which conversion to more humane farming methods would offer greater protection for human health.
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