Yersinia in Pork

Yersinia in Pork
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This week Consumer Reports released a study showing the majority of retail pork tested was contaminated with antibiotic-resistant strains of the foodborne bacteria Yersinia enterocolitica.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Every year, the federal government tests thousands of retail meat samples for the presence of four types of antibiotic-resistant bacteria. But, Yersinia enterocolitica is not among them. This, despite the fact that nearly 100,000 Americans are sickened by foodborne Yersinia every year. This is yet another public health breach, filled this week by Consumers Union.

Pigs are assumed to be the main reservoir for the pathogen, and pork and pork products, the main source of human infection. Most foodborne pathogens tend to come from a variety of sources, but 100% of the attributable Yersinia outbreaks reported in the United States over the last decade or so were caused by pork.

So, how contaminated is the U.S. pork supply? Consumers Union tested nearly 200 pork samples from cities across the country, and found more than two-thirds contaminated with Yersinia—90% of which were resistant to one or more antibiotics.

In most cases, Yersinia food poisoning just causes acute gastroenteritis— characterized by fever; abdominal pain; often bloody diarrhea. Sometimes cases can be confused with appendicitis, leading to unnecessary emergency surgery. Long-term consequences of infection include chronic inflammation of the eyes, kidneys, heart, and joints. Within a year of a bout of Yersinia food poisoning, victims are at 47 times the risk of coming down with autoimmune arthritis. And, the bacteria may also play a role in triggering an autoimmune thyroid condition, known as Graves’ disease.

How widespread is Yersinia in U.S. pigs? A national USDA survey of fecal samples found half of American herds tested were infected. The emergence of human infection over the last century may in part be due to changes in the meat industry, such as slaughter plant consolidation, and an increase in farm size and intensification of production. Higher stocking densities of pigs on factory farms is one of the factors that’s been associated with increased prevalence among herds. Inside some swine confinement buildings, researchers have been able to culture the bacteria right out of the air.

The pork industry crowds pigs because overcrowding pigs may pay, according to the trade publication National Hog Farmer. You can, evidently, maximize profits by dropping the space per pig to six square feet—that’s like a 200-pound pig in the equivalent of two feet by three feet. They acknowledge this presents some problems—inadequate ventilation, increased health risks—but, sometimes, crowding…pigs a little tighter will make you more money.”

The equation for pork producers is even simpler when it comes to Yersinia, since the bacteria does not cause clinical disease in pigs. Thus, it does not present a production problem. The fact that the industry bottom line isn’t directly affected, no matter how high infection rates climb, may explain why there’s no industry-wide Yersinia monitoring and control programs in place in the United States. The costs of crowded confinement can simply be passed on to the tens of thousands of Americans who continue to be sickened every year, at an annual cost estimated at a quarter billion dollars.

Research from Europe suggests pigs raised using organic methods may have 50 times lower odds of harboring infection, compared to pigs raised conventionally. Unfortunately, you can’t really extrapolate that to the U.S., since organic production here is really more about what animals are fed, rather than how they are treated. The researchers attribute the lowered infection rates to factors like lower stocking densities, and lower levels of stress among the animals.

If stress is indeed a contributing factor, things may be looking up in Europe. On January 1, 2013, just about a month away, gestation crates for pregnant pigs are going to be banned across all 27 nations of the European Union—whereas in the U.S., where crating continues to be a predominant practice, pregnant sows have been shown to have among the highest prevalence of Yersinia infection. Though consumers don’t directly eat as many of the moms, the sows can be a source of infection for piglets, who can then carry the infection through to slaughter.

“Practices that restrict natural motion, such as [these] sow gestation crates, induce high levels of stress in the animals and threaten their health, which in turn may threaten [our] health [too].”

Crated sows have been shown to have impaired immunity—thought to be as a result of elevated stress hormone levels, related to the frustration of normal maternal behaviors, like nest building.

Yersinia is one of the reasons why the disease resistance of mother pigs matters when it comes to public health. Thankfully, major retailers, restaurant chains, and leaders in the pork industry have started phasing out gestation crates, which may end up improving the welfare of both animals and humans.

Another proposal to break the Yersinia cycle from farm to fork is to pay producers an incentive bonus if they keep Yersinia-free flocks. That’s the carrot. And the stick is that fresh meat would only be allowed from infection-free herds, diverting pork from infected herds to just making pre-cooked products.

“Although such a two-way splitting of pig-meat production would pose a logistic problem,” it could be actually possible if “enough emphasis were to be placed on cost/benefit for public health.”

There are also measures effective at reducing Yersinia contamination of the meat in the slaughter plant. “By sealing off the [excised] rectum with a plastic bag” during evisceration, you may get a ten-fold drop in carcass contamination. According to data from the Norwegian National Institute of Public Health, human Yersinia infection rates dropped about 25% after the introduction of the plastic bag technique across pig slaughterhouses in Norway.

Let me end by putting the new Consumer Reports finding in perspective. Yersinia in pork ranks only sixteenth in terms of the greatest foodborne disease burdens in the United States.

The worst, in terms of societal cost and quality-adjusted years of life lost, is poultry-borne Campylobacter bacteria—found contaminating 38% of chicken breasts in the latest retail meat survey released this year.

Then comes the Toxoplasma brain parasite in pork; Listeria in deli meat; and Salmonella in, again, poultry.

So, as concerning as this new report may be, the greatest safety concern may be the original white meat.

Please consider volunteering to help out on the site.

Special thanks to pradtf for his all-hands-on-deck help to get this breaking news video up and out. Images thanks to Farm SanctuaryThe Humane Society of the United StatesChb via Wikimedia; and sheyne via flickr

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Every year, the federal government tests thousands of retail meat samples for the presence of four types of antibiotic-resistant bacteria. But, Yersinia enterocolitica is not among them. This, despite the fact that nearly 100,000 Americans are sickened by foodborne Yersinia every year. This is yet another public health breach, filled this week by Consumers Union.

Pigs are assumed to be the main reservoir for the pathogen, and pork and pork products, the main source of human infection. Most foodborne pathogens tend to come from a variety of sources, but 100% of the attributable Yersinia outbreaks reported in the United States over the last decade or so were caused by pork.

So, how contaminated is the U.S. pork supply? Consumers Union tested nearly 200 pork samples from cities across the country, and found more than two-thirds contaminated with Yersinia—90% of which were resistant to one or more antibiotics.

In most cases, Yersinia food poisoning just causes acute gastroenteritis— characterized by fever; abdominal pain; often bloody diarrhea. Sometimes cases can be confused with appendicitis, leading to unnecessary emergency surgery. Long-term consequences of infection include chronic inflammation of the eyes, kidneys, heart, and joints. Within a year of a bout of Yersinia food poisoning, victims are at 47 times the risk of coming down with autoimmune arthritis. And, the bacteria may also play a role in triggering an autoimmune thyroid condition, known as Graves’ disease.

How widespread is Yersinia in U.S. pigs? A national USDA survey of fecal samples found half of American herds tested were infected. The emergence of human infection over the last century may in part be due to changes in the meat industry, such as slaughter plant consolidation, and an increase in farm size and intensification of production. Higher stocking densities of pigs on factory farms is one of the factors that’s been associated with increased prevalence among herds. Inside some swine confinement buildings, researchers have been able to culture the bacteria right out of the air.

The pork industry crowds pigs because overcrowding pigs may pay, according to the trade publication National Hog Farmer. You can, evidently, maximize profits by dropping the space per pig to six square feet—that’s like a 200-pound pig in the equivalent of two feet by three feet. They acknowledge this presents some problems—inadequate ventilation, increased health risks—but, sometimes, crowding…pigs a little tighter will make you more money.”

The equation for pork producers is even simpler when it comes to Yersinia, since the bacteria does not cause clinical disease in pigs. Thus, it does not present a production problem. The fact that the industry bottom line isn’t directly affected, no matter how high infection rates climb, may explain why there’s no industry-wide Yersinia monitoring and control programs in place in the United States. The costs of crowded confinement can simply be passed on to the tens of thousands of Americans who continue to be sickened every year, at an annual cost estimated at a quarter billion dollars.

Research from Europe suggests pigs raised using organic methods may have 50 times lower odds of harboring infection, compared to pigs raised conventionally. Unfortunately, you can’t really extrapolate that to the U.S., since organic production here is really more about what animals are fed, rather than how they are treated. The researchers attribute the lowered infection rates to factors like lower stocking densities, and lower levels of stress among the animals.

If stress is indeed a contributing factor, things may be looking up in Europe. On January 1, 2013, just about a month away, gestation crates for pregnant pigs are going to be banned across all 27 nations of the European Union—whereas in the U.S., where crating continues to be a predominant practice, pregnant sows have been shown to have among the highest prevalence of Yersinia infection. Though consumers don’t directly eat as many of the moms, the sows can be a source of infection for piglets, who can then carry the infection through to slaughter.

“Practices that restrict natural motion, such as [these] sow gestation crates, induce high levels of stress in the animals and threaten their health, which in turn may threaten [our] health [too].”

Crated sows have been shown to have impaired immunity—thought to be as a result of elevated stress hormone levels, related to the frustration of normal maternal behaviors, like nest building.

Yersinia is one of the reasons why the disease resistance of mother pigs matters when it comes to public health. Thankfully, major retailers, restaurant chains, and leaders in the pork industry have started phasing out gestation crates, which may end up improving the welfare of both animals and humans.

Another proposal to break the Yersinia cycle from farm to fork is to pay producers an incentive bonus if they keep Yersinia-free flocks. That’s the carrot. And the stick is that fresh meat would only be allowed from infection-free herds, diverting pork from infected herds to just making pre-cooked products.

“Although such a two-way splitting of pig-meat production would pose a logistic problem,” it could be actually possible if “enough emphasis were to be placed on cost/benefit for public health.”

There are also measures effective at reducing Yersinia contamination of the meat in the slaughter plant. “By sealing off the [excised] rectum with a plastic bag” during evisceration, you may get a ten-fold drop in carcass contamination. According to data from the Norwegian National Institute of Public Health, human Yersinia infection rates dropped about 25% after the introduction of the plastic bag technique across pig slaughterhouses in Norway.

Let me end by putting the new Consumer Reports finding in perspective. Yersinia in pork ranks only sixteenth in terms of the greatest foodborne disease burdens in the United States.

The worst, in terms of societal cost and quality-adjusted years of life lost, is poultry-borne Campylobacter bacteria—found contaminating 38% of chicken breasts in the latest retail meat survey released this year.

Then comes the Toxoplasma brain parasite in pork; Listeria in deli meat; and Salmonella in, again, poultry.

So, as concerning as this new report may be, the greatest safety concern may be the original white meat.

Please consider volunteering to help out on the site.

Special thanks to pradtf for his all-hands-on-deck help to get this breaking news video up and out. Images thanks to Farm SanctuaryThe Humane Society of the United StatesChb via Wikimedia; and sheyne via flickr

Doctor's Note

This is the second of two “breaking news” videos about the findings this week, from Consumer Reports, of the growth-promoting drug ractopamine, and antibiotic-resistant Yersinia bacteria in a significant proportion of U.S. pork tested. See Ractopamine in Pork for the first part, addressing the drug residue findings. For more videos on fecal matter contamination of the meat supply, see Food Poisoning Bacteria Cross-ContaminationChicken Out of UTIs; and Fecal Bacteria Survey. The Campyobacter in chicken that I end the video on is the Poultry and Paralysis bacteria. 

For more context, check out my associated blog posts: Ractopamine and Yersinia in U.S. PorkBugs & Drugs in Pork: Yersinia and RactopamineShould We Avoid Titanium Dioxide?; and Probiotics and Diarrhea.

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36 responses to “Yersinia in Pork

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  1. And yet people still want their bacon. Humans are a stubborn species. When the information is there and you don’t utilize it you have only yourself to blame.

    1. Kathi,
      Yes that is true people are stubborn. And even when people/patients learn the truth they still don’t want to take ownership of their actions.
      Which is truly amazing to me because life is quite clearly a cause and effect system.

      1. With all due respect, HemoDynamic, M.D., life may be about cause and effect, but individuals are a bit more complicated than that. Have you heard of change psychology, specifically about motivational interviewing? If you are interesting in exploring it, I recommend reading up on motivational interviewing for healthcare professionals as a useful (and quick) technique and intervention that you can use in your medical practice to help people change their bad habits. This might be a good place to start: Health Behavior Change: A Guide for Practitioners.

    2. I agree people often exhibit resistant behaviors and hang on to their beliefs and ways of doing things despite facts indicating that their actions are harmful to them. There are many complicated reasons for this (one of them being human psychology and the other being the power and influence of money). That said, I strongly disagree with your statement that “you only have yourself to blame” [for what exactly?]. I think it is best to be very cautious and careful when blaming individuals’ (i.e., consumers’) inability to change certain aspects of their lives for the better, especially when the manipulative actions of the meat and food industry (or any other multi-billion/trillion dollar industry, for that matter) are at play. Blaming the victim is too simple and too easy. The reality of changing behaviors and actions is much more complicated.

      Yes, there is information out there,but it is often not readily available, presented in a confusing context, seemingly conflicting, or actively suppressed.That is why this site exists, to counter some of these challenges and to make nutritional information more accessible to those who can access it in this forum (sadly, in this day and age many still do not have access to the internet not to mention other sources of credible information)! In Dr. Greger’s own words: “… a significant part of the problem is that individuals … are faced with a deluge of confusing and conflicting nutritional advice. The goal of this website is to present you with the results of the latest in nutrition and health research, presented in a way that is easy to understand.” (Taken from the site’s “About” page.)

      We have to remember that change, both personal and cultural, is complicated; it is very difficult, takes time, and (a lot of) patience to develop new ways of doing things, especially when starting new healthier habits. Just knowing that something is bad for us, usually is not enough to go about changing a habit or behavior (I wish it were that easy!). The health problems the world is facing are multi-layered and complicated, and should be approached from that perspective and understanding if we truly want to bring about healthier changes. Blaming the victim will not win converts or bring about healthier ways of living. Education, patience, persistence, compassion, access to reliable information, and healthier food sources will.

      Yes, change is frustrating slow, but it IS happening. Already many individuals and society have made huge strides when it comes to nutrition and wellness. What is currently happening in this arena is truly revolutionary and exciting.

      1. Beautifully said–blaming the victim is not the answer. I need to lose 30 pounds, and I eat healthy. I am a vegetarian; I just eat too much. I am a teacher, and I work10-12 hours most days. I teach in a poor area, and my students need extra tutoring–they can’t pass my class since they are so behind. I eat for energy, for comfort, for the joy of it. Thank you for understanding the complex problem of a person’s diet.

  2. It is so hard to get this message “out there”. Over Thanksgiving, I had a family member try to tell me that all you really have to worry about health-wise is how meat is cured. “If you stay away from bacon, etc., you have nothing to worry about.” oh good grief.

      1. You’d think. Since NutritionFacts came on-line I’ve tried sending her several various blogs and links to videos on Nutrition Facts. She has had breast cancer among several other health problems that are directly addressed here on NutritionFacts. She’s not interested. Her doctors are right, and she can’t hear anything else.

        She even tried to sell me on some new study which shows that the cholesterol in eggs is different than the cholesterol in other animal products. Supposedly the cholesterol in eggs does not harm humans as much… I didn’t even have to ask who produced that study.

        You can’t force people to take in what they simple are not interested in taking in.

        Thanks for your reply.

        1. True that, no body likes to be forced to do anything.

          Encouraging healthy change is trying, often frustrating, and not always possible. You deserve much credit for trying to point her in the right direction.

          Your egg study story made me think of Dr. McDougall’s saying: “People love to hear good news about their bad habits.”

        2. Hey Thea. Thanks for your post. Just thought I would share some thoughts.
          Maybe your family member was not ready for nutritionfacts.org. Obviously your intention was great and nutritionfacts.org is a fantastic place to learn more about the health benefits of a plant-based diet. But was her education level high enough to appreciate this website? Judging from your statement “Her doctors are right, and she can’t hear anything else.”, I suspect that sending her Bill Clinton or some other famous vegan’s testimonial would have done her more good.

          Although Dr. Greger is doing a great job of communicating complex and technical ideas in a relatively accessible manner, I think nutrionfacts is still filtering people out based on education level. Many people who have limited science education would probably find the arguments presented on this website to be too abstruse for them to follow.
          Most people want a quick solution. The radical approach articulated by Dr. Greger requires hard work. We live in an age where the financial forces are doing whatever they can to homogenize our interests. Going against the norm requires tremendous skill and inner strength.

          1. Very well said BPCveg. Level of education and economics (really the two are inter-related) play an enormous role in how accessible and understandable wellness and health information are to folks. (As does how willing someone is to hear what is being shared with them.) You offer some great alternative suggestions on how to share some of this plant-based information with folks.

          2. BPCveg: Thanks for your thoughts. I think you may be right in some cases, but my experience is that this sort of thing has nothing to do with education level. A case study in point: my family member is very highly educated and has served in high level positions in major hospitals (this is a partial clue to her opinion about doctors) and universities. I have had many intelligent conversations with her on a variety of topics over the years.

            I think this problem in our society is much more about confusion and lack of will than anything else. I used to be in the same boat. I simply was not able to take in any nutrition information that did not conform to what I heard in the media because a) I did not trust non-standard sources of information and there is so much conflicting information out there, b) I’m not the type of person who generally believes in conspiracies (so I want to believe that the government and people like Dr. Oz are ethical) , and c) I did not want to change my diet.

            That last one is a biggie for most people. They simply lack the will to change. Then when they consider doing so, they are lost in the sea of conflicting and missing information. That is why I made my original post. It is important to change what gets said/known by the general population. ie: Right now, everyone knows… What we need is for everyone to know the type of information in this video and others on this site.

            Though I will say that I absolutely agree with you that some people are more swayed by role models/famous people than others. So you are right that sending some people stories about Bill Clinton will go further with them than a blog post from this site. That’s not a bad thing. It is just something that is.

            I also agree with you about the “tremendous skill and inner strength” that is needed to buck current trends. Oh yes.

            1. Hey Thea,

              The story of this family member that you describe is very surprising and dissapointing to me. What I have gathered so far is that: 1- she is highly educated (in an area relevant to science, may I assume?); 2- she has had serious health problems (including breast cancer); 3- she is willing to argue about the connection about food versus health (even if you don’t necessarily agree with her specific arguments); 4-she is not open to any of the information presented on nutritionfacts.org. Under these circumstances, it is hard to see how she would lack the motivation to change her diet at all.
              Maybe you are right when you suggested that she is just reluctant to go against the establishment. If that is the case, why not send her the standard position on vegan/vegetarian diets by the largest organization of dieticians on planet earth, which by definition is the establishment. Follow the link below for more:

              http://www.eatright.org/about/content.aspx?id=8357

              As indicated by the link above, going vegan is really not that radical anymore. I think that the most radical and challenging position of nutritionfacts.org is that members of the general public should optimize their diet in accordance with the latest scientific evidence (even before it has been fully scrutinized by the scientific community). As you know, this goes way beyond simply being vegan.

          3. It’s funny, one thing I really love about these videos is that they are so short and easy to follow without overloading you with information. I share them all the time with people specifically because I know no one’s going to be reading the books or following the blogs I recommend to them, but everyone’s got a spare couple of minutes for their health, right? Alas, I don’t think the people who could most benefit from them give a hoot. I understand being ignorant – I certainly was – but how does someone purposely keep themselves in the dark on this sort of thing? I just don’t get it.

              1. Indeed, it is very frustrating when you want to help someone improve their lives but they are resistant to it. This resistant behavior, however, is a very common trait in people. Information and facts alone are usually not enough to motivate people to change. Changing one’s habits is a process that occurs in stages and that frequently takes a long time. One of the key tenets of working with people to change their behaviors–or to help them in any way– is to meet them where they are (and not where you would like for them to be). I will, again, refer to the ideas behind motivational interviewing (see my comments and links above), a counseling approach developed from working with those with drinking problems and one that is now being broadly applied in various helping fields as a tool to help people make healthy changes in their lives (whether it be to quit drinking, stop smoking, practice safer sex, eat better, exercise more, the list goes on and on).

                Those of us who want to help our family, friends and patients make positive healthy changes in their lives would be wise to learn more about the techniques and process involved in motivational interviewing. We must understand that helping someone make a change involves more than just sharing knowledge (e.g. these fantastic mini videos)
                with them about why making a change would improve their health. While knowledge is definitely an important tool in the change tool-kit, it cannot and must not be the only one. Pressuring an individual towards change when they have not expressed a desire to do so will only make them more resistant to hearing what you have to say and/or to encouraging them to make any positive changes. Change facilitators need to be able to utilize all the tools in the behavior change tool-box, and those tools include compassion, a sense of partnership, a non-judgmental approach, a stance of open examination, the ability to offer suggestions, and the flexibility to work with resistance that will inevitably come up. The idea is to meet people where they are to tip the balance towards healthier behaviors and to help them set their own realistic goals –however tiny.

                In sum, when we share these videos with the ones we care
                about, we need to be aware of our own motives behind sharing the information included in the videos. Is it simply to educate or is it to encourage someone to change their behavior? The former is easily done by simply sharing the video, whereas the latter is more complicated and will encompass a more involved and collaborative approach. We need to be careful that we do not conflate our own motives in an attempt to assist our loved ones in making positive behavioral changes, especially if they have no desire to change. At the very least, all we can hope for is
                that we spark an interest in them that will enable and encourage them at some point to make positive changes in their lives—at their own pace. And, once they are ready to do that, we need to be ready to support them.

                1. Thanks for your excellent synopsis of motivational interviewing. I will recommend the book you suggested to my non-fiction book club members.

          4. I tend to disagree. I think Dr. Greger sums up the main points in a very simple manner and if one is looking for more of a science base they can view the studies cited.

            1. I forwarded The Leading Cause of Death to my cousin. She told me she couldn’t watch it because it was too technical. Maybe just an excuse?

                1. I know right! She is 100 pounds overweight and has diabetes. I think it’s just overwhelming for her. But she can tell me it’s too technical.

  3. Thanks for these 2 “breaking news” videos! Dr Greger, you really went into “overdrive” to put these videos out in a timely manner. I was reading these news reports online and was thinking that you’d be interested in making future videos based on these Consumer Reports findings; i never thought you’d come out with these videos the very next day!

  4. Awful. I ate a lot of pork products growing up and now I’m wondering if it had anything to do with me developing Rheumatoid arthritis at the age of 14.

    1. Being of Slavic heritage I have also eaten my fair share of pork products back in the day (and even not so long ago). If it is any consolation
      at all, I think that the quality of pork (and other meat/food products) may have been different (read: better) in the past, as it seems that the meat/food industry has gotten more involved (for lack of a better word) in manipulating the food we eat for their profits.

      BTW- Have you watched Dr. G’s videos on RA? (You can do a search for videos on the topic on this site.)

  5. Thank you for all these amazing informations !!! very clear and helpfull !
    Is there anything in the literature related to the causes and or natural remedies for grave’s disease ? Selenium may help prevent exophtalmy, plant based diet to reduce inflammation …. Anything else ? Any advices ?

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