Campylobacter Infection: The Danger Lurking in Factory Farmed Chickens

British researchers have established that chickens raised in a stressful environment are more likely to transmit campylobacter infections to human consumers.

| October/November 2010

campylobacter infection - factory farmed chickens

Poor conditions endured by factory farmed chickens increases the levels of a stress hormone that promotes the growth of Campylobacter, which in turn increases the risk of campylobacter infection in humans.


For years, as scientists noted what appeared to be a link between increased stress in animals and increased instances of disease, supporters of humane livestock production have suggested a happy animal is a healthier animal. Now a team of researchers from the University of Bristol in the United Kingdom has discovered that high levels of a stress hormone in chickens actually increase the risk of Campylobacter infection.

Campylobacter is a foodborne bacteria that infects an estimated 2.4 million people each year and is one of the top causes of foodborne illness in the United States, according to the Centers for Disease Control and Prevention (CDC). The bacteria can live in the intestinal tract of even healthy birds, passing from bird to bird through common water sources or contact with feces. In humans, Campylobacter infection causes symptoms such as diarrhea, cramping, abdominal pain, nausea, vomiting, and fever within two to five days of exposure. The CDC estimates the bacteria kill approximately 124 people nationwide per year.

The British researchers initially surveyed nearly 800 broiler flocks in the United Kingdom and determined risk factors for infection. They found that the health and welfare of the chickens was a significant factor in the proliferation of Campylobacter. “If you compromise the host chicken, its ability to control the infection is also compromised,” says Tom Humphrey, lead researcher for the team who is now a professorial fellow in food safety at the University of Liverpool and science director for the National Centre for Zoonosis Research.

When the researchers isolated the stress hormone norepinephrine and began studying its effects in the laboratory, they found a series of disturbing results. The stress hormone caused rapid growth of Campylobacter and increased its virulence and gut permeability, giving the bacteria an easy way out of the gut and into the chicken meat. “The bacteria’s ability to affect the chicken is enhanced if the bird is in a stressful situation, and the bacteria is also more likely to infect muscle tissues,” Humphrey says.

Factory farmed chickens provide an ideal environment for the proliferation of Campylobacter. “You’ve got heat stress, rapid growth stress, ammonia stress due to poor air circulation, broken bones from rough handling,” says Temple Grandin, an expert in low-stress animal handling facilities and professor of animal science at Colorado State University. “There are huge differences between the chickens coming off well-managed farms [that show regard for the animals’ emotional well-being] and poorly managed farms.”

A few bacteria contained in the intestine may rarely come into contact with a consumer, whereas a stressed chicken will have an increased level of Campylobacter cells that have traveled into the surrounding meat, making the bacteria nearly unavoidable in our kitchens. The Food Safety and Inspection Service (a division of the U.S. Department of Agriculture) reports that the bacteria can be found in almost all raw poultry. Even one drop of juice from a raw chicken is enough to cause food poisoning in humans. According to the CDC, Campylobacter infection can be avoided by handling raw meat properly prior to cooking. Cook chicken until it reaches a minimum internal temperature of 165 degrees Fahrenheit, and thoroughly wash hands, utensils, countertops, and especially cutting boards to prevent cross-contamination of other foods.

carol bennett
1/7/2013 11:16:19 PM

Dear Mother, I have read you for years and learned so much. Today I watched "Food, Inc" on my Kindle. Even though I have read Salatin and love articles on Polyface?sp farms and agree that something needs to be done regarding our food, seeing farming practices on video was a hard punch in the stomach. If you haven't seen this, watch it. If you haven't at least tried changing eating habits and sources, do so. God help us!

diana boeke
10/4/2011 1:02:04 PM

I agree that Mother is getting rather sloppy with its articles. This one looks like it was based on nothing more than other internet articles. And a picture of layers to go with an article on broilers? However, as a SMALL (one hundred a month) producer of free-range, pastured broiler chickens, I do say there is a huge difference between the way I treat my birds and the way industrial farms do. Yes, they are interested in lowering the stress levels of the birds, but from what I read, they do this through climate control with big fans and humidity controllers, mostly. Our climate control on the farm involves bringing ice water to them on the field during heat waves and providing plenty of shade. We also transport them in small groups on a wagon about 100 yards to our processing area. We move the coops by hand daily when the birds are outside foraging, and when we need to move them, pick them up gently, never carrying them by their feet, right until the point of slaughter. I'm quite sure they get a blast of stress hormone at that point, but they haven't lived with chronic stress hormone elevation for their entire short lives. I do think that makes for a healthier bird, as medical studies have shown that elevated stress hormones in humans contribute to disease. It's a leap perhaps, yes, but a reasonable one. And even at $3.50/lb for our chickens, we figure we're making less than $1.00/hour. But they keep our land fertile and give us good compost material for our vegetables, so it all works out sustainably.

abbey bend
9/28/2011 10:00:01 PM

As Karl mentioned this article is just plain doo doo! It is however a very non-factual blend of information about raising chickens in the UK, very different from the United States and some comments taken very out of context by Grandin and Humphrey! Why is Mother Earth not doing any due dilegence on these articles??? Just because one or two facts are sprinkled into the article, does not make it truthful or useful in any way, shape or form!! If I want fiction, then I think Stephen King is a better writer!

karl buesching
11/28/2010 5:50:27 PM

"Mother" has always been a source of un-biased, practical information and advice based upon common sense. This article is none of those things. The birds shown in the picture are not even broilers! They're layers! The uneducated (on poultry production) reader would make the leap that factory farming is the source of the problem when the VAST MAJORITY of broiler farmers treat their flocks in a humane way. In fact, maintaining a healthy, low stress environment for the flock is the number one concern of a poultry farmer. Mother, please leave the sensational and exaggerated reporting to the extremists.

p l
10/24/2010 12:49:18 AM

I'm of the same opinion. Less government. We left England to get away from the over governed, beaurocratic B.S. that we are experiencing today. And look at us, a few hundred years later and like father, like son. It's kind of pathetic, actually. And we have no other countries to go colonize to get away from it (my apologies to the indigenous peoples of the U.S.- it would not be my intention to uproot another nation to take their land). This is why I have chickens in my backyard, a big dog, and if anyone wants to come around my property sticking their nose in and wanting to dictate to me what I can do and when I can do it, well.... my right to bear arms and a 12 guage is lookin' better and better the more government B.S. I see. What's sad is that the FDA funds what is approved to eat in schools. It also funds what is approved to buy with foodstamps. Very little organic, humane raised food is approved for foodstamps. So, the end result is that those that are poor are forced to eat the food that is less than healthy, and the government says that is healthy. You can go buy raw chicken at the supermarket that has God knows what in it with foodstamps, but I can't go buy a live chicken. How screwed up is that???? That's why it's my goal to become as least dependent on the grid and government as humanly possible and then when everything goes completely to crap, I will have food.

t brandt
10/21/2010 9:23:26 PM

Facts: 7 BILLION chickens produced in the US each year & 124 deaths from Campylobacter (not all from contaminated chicken), ALL of which could have been prevented by proper handling & preparation of the food. This sort of poorly researched & thought out article attempts to create a problem where none exists. We have too many regulations now, most of which produce no discernable benefits, but do raise costs. We reached the point of diminishing returns in govt regulation of the food industry long ago. Humane handling of livestock, including chickens, does produce a more tender & tastier meat (I'm a producer of orgainic beef) but provides NO health benefit.

10/18/2010 1:56:25 PM

Thanks for your comments, Gary. And I agree, to a point. I actually pay $3.50/lb to a local farmer for chickens raised organically out on grass. And I wish everyone could do the same. In the meantime, if all producers can move that much closer to more humane and healthy management--reducing the stress of their flocks and improving living conditions--then I applaud their efforts.

gary maske
10/16/2010 7:01:56 AM

Come to think of it, perhaps the industry commissioned this research. Do you see the logic? Mr. Humphrey conducts the research and concludes "the industry needs help." The industry could take this information to the USDA in order to get lower stocking densities enforced. The result would be the consumer would need to pay "two or three pence more for a chicken." The new label would read "Reduced Stocking Density Chicken." But, no, healthy chicken does not come from raising the price of chicken from 79 cents a pound to 82 cents a pound due to lower stocking densities. (Sorry, I converted from pence to cents.) Good chicken will cost you around $3/lb. Americans are used to cheap food. But the real cost is incalculable since it is paid in health care premiums and expenses.

gary maske
10/16/2010 6:40:12 AM

The industry needs help? What an inane prescription. That is like the doctor who correctly diagnoses cancer and then prescribes aspirin. The industry does not need help. It needs to go broke. Reduce stocking densities? No, you cannot tweak this production system. It is fundamentally flawed. No political action is necessary or even warranted. Consumers can vote with their pocketbooks by buying non-industrial chicken, or nothing will come of this at all. However a more likely outcome of research like this is that we will get even more government regulation. And how will that help the small chicken farmer raising his chickens on grass? Not at all. To the contrary, he will have more regulatory hoops to jump through at the end of the day then he did at the beginning. Why? Because "even one drop of juice from a raw chicken is enough to cause food poisoning in humans." What do you think the USDA will do with this? The more morally corrupt our world becomes, the more consumed by antiseptic cleanliness it becomes, the bigger the USDA gets. I'm sorry, this article is not part of the solution, it is part of the problem.

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