Yersiniosis

Yersiniosis is an infectious disease of the gastrointestinal tract caused by bacteria of the genus Yersinia other than Y. pestis. Most cases of yersiniosis in humans are caused by Y. enterocolitica, with a small minority being caused by Y. pseudotuberculosis. Rarely, other species of the genus can cause yersiniosis.

Yersiniosis most frequently affects young children. The infection is thought to be contracted through the consumption of undercooked meat products, unpasteurized milk, or water contaminated by the bacteria. It has been also sometimes associated with handling raw chitterlings. However, most cases of yersiniosis lack a clear source, and are considered sporadic.

Y. pestis is not considered to be a causative agent of yersiniosis because it is the organism that causes Plague, which is considered to be a distinct disease.

Signs and symptoms
Infection with Y. enterocolitica can cause a variety of symptoms depending on the age of the person infected. Common symptoms include:


 * Fever
 * Abdominal pain
 * Diarrhea (typically bloody)
 * Vomiting

Symptoms typically develop 4 to 7 days after exposure and may last 1 to 3 weeks or longer. In older children and adults, right-sided abdominal pain and fever may be the predominant symptoms, and may be confused with appendicitis. In a small proportion of cases, complications such as skin rash, joint pains, ileitis, erythema nodosum, and sometimes sepsis, acute arthritis or the spread of bacteria to the bloodstream (bacteremia) can occur.

Transmission
The natural reservoir animals for Y. enterocolitica are swine, including domesticated pigs and wild boars. Most cases of human yersiniosis are thought to be due to either consumption of undercooked meat from pigs, or poor sanitation allowing fecal matter or blood of pigs to contaminate objects and food items near them.

Because of the frequency of associations between human and pig strains of yersiniosis, it is often referred to as a zoonotic disease.

Diagnosis
Most diagnoses of yersiniosis are made via ELISA immunoassay testing. However, in locations without access to this form of testing, traditional bacterial cultures may be created and then biochemically tested.

Many cases of yersiniosis are initially misdiagnosed as appendicitis, which is much more common and may present with similar symptoms.

Treatment
Treatment for gastroenteritis due to Y. enterocolitica typically requires only symptomatic treatment of diarrhea with common anti-diarrheal drugs. Severe infections with systemic involvement (sepsis or bacteremia) often requires aggressive antibiotic therapy; the drugs of choice are doxycycline and an aminoglycoside. Alternatives include cefotaxime, fluoroquinolones, and co-trimoxazole. Standard antibiotics such as penicillin are often ineffective due to the production of beta-lactamase enzymes by Yersinia species.