Yersiniosis is a zoonotic foodborne infection caused by Yersinia enterocolitica or Y. pseudotuberculosis — bacteria primarily associated with pigs (pork is the dominant food source) that are notable for their ability to multiply at refrigerator temperatures. In the EU, yersiniosis is the third most common zoonotic enteric disease after campylobacteriosis and salmonellosis. Clinical presentation: acute gastroenteritis (fever, diarrhoea, abdominal cramps — 3-7 days); the pseudoappendicitis syndrome (right lower quadrant pain from mesenteric lymphadenitis mimicking appendicitis — especially in older children and young adults); and post-infectious reactive arthritis.

What causes yersiniosis and what foods are implicated?

Primary source: pigs — Y. enterocolitica biotype 4/O:3 colonises pig tonsils, intestines and faeces asymptomatically. Human exposure: raw or undercooked pork (especially minced pork, chitterlings/pig intestines, pork sausages); cross-contamination from pork to other foods; unpasteurised milk; contaminated water. A unique feature: Yersinia grows at 4°C — so properly refrigerated pork products can accumulate more bacteria over time, unlike other foodborne pathogens that are inhibited by refrigeration.

How does yersiniosis differ from appendicitis?

The pseudoappendicitis syndrome of yersiniosis is clinically, biochemically and even radiologically indistinguishable from acute appendicitis: right lower quadrant pain and tenderness; fever; elevated white cell count and CRP; pain worse on palpation at McBurney's point; ultrasound showing a fluid-filled structure in the right iliac fossa (enlarged inflamed lymph nodes mimicking an inflamed appendix). The differentiation is made at surgery (if performed): normal appendix + enlarged mesenteric lymph nodes = mesenteric lymphadenitis. Post-surgical cultures of the mesenteric nodes grow Yersinia.

Who is most at risk of severe yersiniosis?

Severe systemic yersiniosis (bacteraemia, liver/spleen abscesses, septicaemia) is rare but occurs in: patients with iron overload (haemochromatosis, thalassaemia, sickle cell disease — Yersinia requires iron and is enhanced by excess iron); patients on deferoxamine (iron chelation therapy — paradoxically increases available iron for Yersinia via the ferrioxamine siderophore); immunocompromised patients; diabetics; elderly individuals; patients with liver cirrhosis.

Is there a vaccine or specific treatment?

No vaccine exists for yersiniosis. Most cases in immunocompetent individuals are self-limiting (1-3 weeks) — supportive care with oral rehydration is sufficient; antibiotics are not routinely recommended. Antibiotics for: severe, prolonged or systemic disease (bacteraemia, liver abscess): doxycycline + aminoglycoside (gentamicin); or ciprofloxacin + ceftriaxone. Y. enterocolitica is intrinsically resistant to penicillin and ampicillin (beta-lactamase producing). Post-infectious reactive arthritis: NSAIDs for symptom control; usually self-limiting; rarely requires DMARDs (sulfasalazine) for persistent joint disease.

How does GMJ News cover yersiniosis?

GMJ News covers ECDC/EFSA yersiniosis surveillance data, pork as the primary vehicle, refrigerator temperature growth, pseudoappendicitis syndrome (the diagnostic trap), reactive arthritis, HLA-B27 association, treatment in severe cases, and iron overload as a risk factor. Yersiniosis — the third most common EU enteric zoonosis — is directly relevant to PHIG's food safety and One Health programme.

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Yersiniosis

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

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Yersiniosis — caused primarily by Yersinia enterocolitica (a psychrotrophic bacterium that grows even at refrigerator temperatures) and Y. pseudotuberculosis, predominantly transmitted through raw or undercooked pork — is the third most common zoonotic enteric disease in the EU after campylobacteriosis and salmonellosis (ECDC/EFSA One Health Report), notable for its characteristic pseudoappendicitis syndrome — right lower quadrant pain and fever from mesenteric lymphadenitis mimicking acute appendicitis so closely that thousands of unnecessary appendectomies have been performed (ECDC). A unique property among foodborne pathogens: Y. enterocolitica can multiply at 4°C — meaning properly refrigerated pork products remain infectious — and post-infectious reactive arthritis (HLA-B27-associated) is a recognised complication.

Key messages

3rd most common EU zoonotic enteric disease — pork-associated

Yersiniosis is the third most common zoonotic enteric disease in the EU after campylobacteriosis and salmonellosis. Y. enterocolitica biotypes 3/4 serotype O:3 predominantly from raw or undercooked pork is the dominant source (ECDC/EFSA One Health 2024).

Pseudoappendicitis — mimics acute appendicitis

Y. enterocolitica causes mesenteric lymphadenitis and terminal ileitis — producing right lower quadrant pain, fever and elevated white cell count indistinguishable clinically from acute appendicitis. Thousands of unnecessary appendectomies have been performed in patients with yersiniosis.

Grows in the refrigerator — psychrotrophic

Unlike most foodborne pathogens that are inhibited by refrigeration, Y. enterocolitica can multiply at 4°C — meaning properly refrigerated pork products remain a transmission risk over time.

Reactive arthritis — post-infectious

Reactive arthritis (oligoarthritis, predominantly lower limbs) occurs 1-4 weeks after gastrointestinal yersiniosis, more commonly in HLA-B27 positive individuals. Usually self-limiting (weeks to months), but can become chronic.

Most cases self-limiting — no antibiotics

Most yersiniosis resolves without antibiotics in 1-3 weeks. Antibiotics are reserved for severe, systemic or invasive disease: doxycycline + aminoglycoside (or fluoroquinolone + ceftriaxone for systemic disease).

ECDC mandatory surveillance

Yersiniosis is an ECDC notifiable disease with mandatory EU surveillance — included in the EFSA-ECDC One Health Zoonoses Report as one of the most common human zoonotic infections reported in the EU.

Key statistics

most common zoonotic enteric disease in EU (ECDC/EFSA One Health 2024)

ECDC/EFSA 2024

~8,400

confirmed yersiniosis cases/year in EU (ECDC annual data)

ECDC

4°C

Y. enterocolitica growth temperature — refrigerator-capable (psychrotrophic)

ECDC/EFSA

HLA-B27

genetic association with post-yersiniosis reactive arthritis

WHO/Rheumatology

Pork #1

pork and pork products primary yersiniosis reservoir and food vehicle

EFSA/WHO

ECDC notifiable

mandatory EU surveillance under Commission Decision 2018/945

ECDC

Yersiniosis EU cases by age group — ECDC annual data

Source: ECDC. Children under 5 have the highest incidence. Pseudoappendicitis peaks in school-age children and young adults.

Glossary of key terms

Yersinia enterocolitica biotypes
ECDCY. enterocolitica has five biotypes (1A — non-pathogenic; 1B, 2, 3, 4, 5 — pathogenic). Human disease predominantly from biotype 4, serotype O:3 (European pigs) and biotype 2, serotype O:9 (less common, cross-reacts serologically with Brucella). Biotype 1B O:8 causes more severe disease in the USA. Biotype 1A (food isolates) is non-pathogenic.

Pseudoappendicitis syndrome
WHO/SurgeryY. enterocolitica infects the terminal ileum and produces mesenteric lymphadenitis (inflammation of lymph nodes in the mesentery) — causing right lower quadrant pain, fever, elevated CRP and WBC, clinically and on ultrasound mimicking acute appendicitis. The misdiagnosis rate before culture results is high. Key: at surgery (when performed), the appendix is normal but mesenteric nodes are enlarged. Culture of the mesenteric lymph nodes confirms yersiniosis.

Psychrotrophic growth
EFSAUnlike most foodborne pathogens that are suppressed by refrigeration (4°C), Yersinia enterocolitica can grow — slowly but significantly — at refrigerator temperatures (4-8°C) and even at -1°C. This means that pork products stored in the refrigerator for extended periods can have increasing Yersinia loads. Cold enrichment (storing food samples at 4°C for 2-3 weeks) is used in laboratories to selectively enrich for Yersinia.

Reactive arthritis
WHO/EULARA sterile inflammatory arthritis triggered by remote infection — occurring 1-4 weeks after gastrointestinal or genitourinary infection. Yersinia is one of the classic triggers (others: Salmonella, Shigella, Campylobacter, Chlamydia trachomatis). Characterised by asymmetric oligoarthritis (predominantly large joints, lower limbs); may include uveitis, conjunctivitis, skin lesions (keratoderma blennorrhagica), enthesitis, and urethritis (historically called Reiter's syndrome). Strongly associated with HLA-B27 (arthritis occurs in approximately 10-30% of HLA-B27+ patients with yersiniosis vs approximately 2% of HLA-B27- patients).

Y. pseudotuberculosis
ECDCThe second pathogenic Yersinia species — causes milder, less frequent human disease. Sources: contaminated water, raw vegetables and fruits, domestic animals. Clinical: self-limiting enterocolitis; Far East scarlet fever-like disease (Izumi fever) in Japan and Russia — fever, rash, toxic shock-like syndrome with diffuse erythema; Y. pseudotuberculosis reactive arthritis. Diagnosis: stool culture (requires cold enrichment or special culture techniques).

Yersinia pestis
WHOYersinia pestis — the cause of plague (bubonic, pneumonic, septicaemic) — is a separate species in the Yersinia genus. It has no direct clinical or epidemiological connection to Y. enterocolitica or Y. pseudotuberculosis. Plague is covered in a separate hub. The name "Yersinia" honours Alexandre Yersin, who identified Y. pestis during the 1894 Hong Kong plague epidemic.

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