Yersinia Enterocolitica Infection: undercooked pork a common cause of food poisoning

Yersinia Enterocolitica Infection: undercooked pork a common cause of food poisoning

Updated with new data from 2018. Yersinia enterocolitica infection (Yersiniosis/Yersinia) is a food-borne illness primarily caused by the bacteria Yersinia enterocolitica. These bacteria are frequently isolated in soil, water, animals, and a variety of foods. Pigs are assumed to be the main carrier of Yersinia enterocolitica.

The most common sources include:
• undercooked pork
• raw chitterlings
• pig intestines

There is an incubation period of 36-48 hours where bacterial replication occurs. Yersinia enterocolitica infection establishes via the digestion of the contaminated food followed by the bacteria crossing the intestinal barrier. The spectrum of disease severity can range from asymptomatic to life-threatening sepsis.

The predominant symptoms of acute Yersinia enterocolitica infection in humans can include:
• Fever
• Abdominal pain especially in lower right quadrant
• Right side low back, hip, and glute pain that has been resistant to therapy
• Diarrhea lasting from one to three weeks

In susceptible individuals, Yersinia enterocolitica can cause more serious chronic illnesses such as microscopic colitis, manifesting in the form of recurrent abdominal pain, watery stools and blood in the stools, and arthritis, which is classified as reactive or postinfectious arthritis. Reactive arthritis is characterized as arthritis usually following a gastrointestinal, urogenital or pharyngeal infection.

Arthritis induced by Yersinia is characterized by robust inflammatory polyarticular arthritis with painful and swollen joints with prolonged stiffness, enthesitis with inflammation of both tendons and ligaments, bouts of intense pain in the thoracic and lumbar spine, as well as deep bone pain due to edema and inflammation of the bone marrow.

Regulations on Pork

Because Yersiniosis is considered to be relatively uncommon, the USDA’s Food Safety and Inspection Service does not test for Yersinia enterocolitica infection in its periodic baseline studies which allows the contaminated pork to end up in the hands of unaware customers without any barriers.

A 2012 Consumer Reports study of raw pork chops and ground pork found 69 percent of samples were contaminated with Yersinia enterocolitica.

According to the US Centers for Disease Control, in the United States annually, there is approximately one confirmed infection per 100,000 people reported per year. Since these cases are severely under-reported, the CDC estimates this annual number to be significantly higher. A recent CDC study in the United States found that approximately 6% of Yersinia enterocolitica infection was travel associated.

Testing for Chronic Yersiniosis

Testing can be done on stool, synovial fluid, or serum. Serum testing is preferred because isolation of the microorganism from the stool or joint/synovial fluid very rarely occurs. Typically, the most reliable test is relied on the demonstration of positive antibodies to Yersinia (preferably IgA) in the blood of affected individuals. If IgA is present, this is the greatest indication of an active/aggressive infection—the higher the titer, the more active.

We use both LabCorp and Quest Diagnostics for testing. LabCorp will report a yes/no answer while Quest will provide a numeric value, which provides a more accurate measure of activity.

labcorp yersinia test results

LabCorp lab results without titer.

yersinia quest lab results

Quest lab results with titer.

Thermography in Diagnosis

Thermography is a non-invasive screening procedure which uses a specialized camera to scan the infrared energy emitted from your body and graphically map and display skin surface temperature visualized in colors. This tool is completely safe, has no contact with the body, and uses no radiation. With a Yersinia enterocolitica infection, we tend to see a change in surface temperature over the lower right quadrant.

thermography image of yersinia enterocolitica infection

Thermography image showing lower right quadrant temperature change.

The Challenge of Diagnosis

Frequently, Yersinia-associated arthritis is misdiagnosed as rheumatoid arthritis or an undifferentiated arthritis. An undifferentiated arthritis describes forms of arthritis that cannot be classified into an established disease category. A good portion of undifferentiated arthritis is in fact a result of chronic infections, Yersinia enterocolitica infection being one of them.

Exposure to Yersinia enterocolitica Infection

Yersinia can survive and grow at refrigeration temperatures of ~4 degrees C.

There are a number of precautions you can take to avoid exposure to Yersinia enterocolitica:
• Avoid raw or undercooked pork. When cooking pork, use a meat thermometer to ensure that it reaches the proper internal temperature, which kills potentially harmful bacteria: at least 145° F for whole pork and 160° F for ground pork.
• Consume only pasteurized dairy products
• Wash hands when preparing food, after contact with animals and after handling raw meat


As part of therapy, it is our practice to combine both antibiotic and anti-inflammatory drugs. The reason for this is inflammation not only occurs in the lymph nodes, but also around the mucosal area of the ileocecal valve. Because of this, antibiotics do not penetrate the thickened mucosal area. The combination is usually one antibiotic and one anti-inflammatory.

Antibiotic Therapy
Fluoroquinolones—cannot be used long-term
3rd and 4th generation cephalosporins

Anti-inflammatory Drugs
5-aminosalicylic acid

We are also firm believers in including integrative therapy with dietary supplements including herbal antimicrobials, probiotics, iron chelator, and dietary modifications. Combine the supplements with the drugs mentioned above, usually one or two at a time.

Anti-microbial Herbs
Anamu (Petiveria alliacea)
Ashoka (Saraca indica)
Cat’s Claw (Uncaria tomentosa)
Neem (Azadirachta indica) 
Olive Leaf Extract
Oregano Oil

Alpha Lipoic Acid–this works well because Yersinia thrives on iron and Alpha Lipoic Acid is an iron chelator and depletes the amount of iron in your body.

Bacillus coagulans is our preferred probioitc for Yersinia enterocolitica infection because it possesses antimicrobial properties.

A recently published study showed that Yersinia pseudotuberculosis* utilizes a specific receptor, CD209, for promoting the infection as well as the spread of the infection. CD209 is a pathogen-recognition receptor expressed on the surface of immature dendritic cells and is involved in initiating the primary immune response. Because CD209 recognizes mannose-rich carbohydrates, it can be blocked by Mannan Oligosaccharides (MOS), a broadly used prebiotic in our practice.

This promising study suggests that MOS should be a part of therapeutic protocols targeting yersiniosis.

* Yersinia enterocolitica and Yersinia pseudotuberculosis both behave in very similar way, and, in fact, it is almost impossible to distinguish one infection from another on the basis of clinical symptoms. Furthermore, serological testing for Yersinia enterocolitica and Yersinia pseudotuberculosis shows significant cross-reactivity. Because of these similarities MOS will work well for infection caused by either.

Dietary Modifications

Follow a low iron and low carb diet as Yersinia feeds on iron and carbs.

If left untreated, Yersiniosis will persist indefinitely. For chronic Yersiniosis, you can expect to be in treatment for one year to eradicate the illness. Yersinia enterocolitica infection can be avoided by making sure pork is cooked properly and stored in proper conditions. If you are experiencing chronic right-sided lower back pain, that is not responding to therapy, testing for Yersinia is something to consider.

Note: This post was originally published in October 2014 and was updated in 2018 to include a more comprehensive description.

photo credit: StuartWebster via photopin cc

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