Yersiniosis

Yersiniosis is an infectious disease of the gastrointestinal tract caused by bacteria of the genus Yersinia, excluding Y. pestis. The primary causative agent is Y. enterocolitica, with Y. pseudotuberculosis responsible for a smaller number of cases. Other species of Yersinia can rarely cause the disease.

The infection is most prevalent among young children and is typically contracted through the consumption of undercooked meat products, unpasteurized milk, or contaminated water. Handling raw chitterlings has also been associated with yersiniosis. Many cases, however, remain sporadic with no clear source identified.

Signs and Symptoms

The clinical presentation of yersiniosis varies depending on the patient's age. Common symptoms include fever, abdominal pain, bloody diarrhoea, and vomiting. The incubation period ranges from 4 to 7 days post-exposure, with symptoms persisting for 1 to 3 weeks or longer.

In older children and adults, right-sided abdominal pain and fever can dominate the clinical picture, often leading to misdiagnosis as appendicitis. Complications can arise in a minority of cases, including skin rash, joint pains, ileitis, erythema nodosum, sepsis, acute arthritis, and bacteraemia.

Transmission

Y. enterocolitica primarily resides in swine, including domesticated pigs and wild boars. Human infection is often traced back to the consumption of undercooked pork or exposure to contaminated objects and food due to poor sanitation practices around pigs. Consequently, yersiniosis is considered a zoonotic disease.

Diagnosis

Diagnosis of yersiniosis is predominantly achieved through ELISA immunoassay testing. In settings lacking access to ELISA, traditional bacterial cultures followed by biochemical testing can be employed. Initial misdiagnosis as appendicitis is common due to the overlapping symptomatology.

Treatment

The treatment for Y. enterocolitica-induced gastroenteritis generally involves symptomatic management of diarrhoea using common anti-diarrheal medications. For severe infections with systemic involvement, such as sepsis or bacteraemia, aggressive antibiotic therapy is necessary.

The preferred antibiotics are doxycycline combined with an aminoglycoside. Other effective alternatives include cefotaxime, fluoroquinolones, and co-trimoxazole. Standard antibiotics like penicillin are typically ineffective due to the production of beta-lactamase enzymes by Yersinia species.

---

Self-assessment MCQs (single best answer)

What is the primary causative agent of yersiniosis?

Which age group is most commonly affected by yersiniosis?

What is a common source of yersiniosis infection in humans?

How long does the incubation period of yersiniosis typically last?

Which symptom is more likely to lead to a misdiagnosis of appendicitis in older children and adults with yersiniosis?

What is the most effective diagnostic method for yersiniosis?

Which of the following antibiotics is NOT effective against Yersinia species due to beta-lactamase production?

What is a known complication of yersiniosis?

In severe cases of yersiniosis, which antibiotic combination is most commonly recommended?

Yersiniosis is considered a zoonotic disease primarily because: