Author(s): Louise Francois Watkins, Cindy Friedman

Infectious Agent

Yersinia species are facultative anaerobic gram-negative coccobacilli. The most common species that cause yersiniosis are Yersinia enterocolitica (serogroups O:3, O:5,27, O:8, and O:9), but disease is also caused by Y. pseudotuberculosis. The term “yersinosis” does not include illness caused by Yersinia pestis, the causative agent of plague, which is discussed separately (see Sec. 5, Part 1, Ch. 15, Plague); discussion of Yersinia spp. in this chapter excludes Y. pestis.

Transmission

Transmission of Yersinia spp. can occur from consuming or handling contaminated food, commonly raw or undercooked pork products (e.g., chitterlings); consuming milk that was not pasteurized, inadequately pasteurized, or contaminated after pasteurization; or drinking untreated water. Yersinia spp. also can be transmitted by direct or indirect contact with animals through the fecal–oral route. Pigs are a major reservoir of pathogenic Y. enterocolitica, but a variety of other domestic (e.g., dogs), farm (e.g., cattle), and wild (e.g., deer) animals can harbor Yersinia spp. Transmission through blood product transfusions has been reported.

Epidemiology

Most yersiniosis cases are reported from northern Europe, particularly Scandinavia, and from Canada and Japan. Yersiniosis is not, however, a reportable condition in most countries (including the United States), and infections in countries without surveillance programs might be underrepresented. In the United States, Y. enterocolitica causes ≈92% of infections with known species information, accounting for approximately 117,000 illnesses, 640 hospitalizations, and 35 deaths every year.

In temperate climates, the risk for infection is increased during cooler months. Children are infected more often than adults. People with diseases that cause high iron levels (e.g., hemochromatosis, thalassemia), including those on iron chelation treatment, are at greater risk for infection and severe disease. The incidence among travelers to low- and middle-income countries is generally low, and most cases are believed to be due to foodborne transmission. A US study found that ≈6% of Y. enterocolitica infections were travel-associated.

Clinical Presentation

The incubation period is 4–6 days (range 1–14 days), and symptom onset might be more gradual compared with infections caused by other enteric pathogens. Enterocolitis is the most common clinical presentation; symptoms typically include abdominal pain, diarrhea (which can be bloody and persist for several weeks), and fever. Sore throat also can occur, particularly in children. Mesenteric adenitis, which presents as pain mimicking appendicitis, has been well described. Necrotizing enterocolitis has been described in young infants. Reactive arthritis affecting the wrists, knees, and ankles can occur, usually 1 month after the initial diarrhea episode, resolving after 1–6 months. Erythema nodosum, manifesting as painful, raised red or purple lesions along the trunk and legs, can occur, and usually resolves spontaneously within 1 month.

Diagnosis

Diagnosis is frequently made by isolating the organism from bile, blood, cerebrospinal fluid, mesenteric lymph nodes, peritoneal fluid, stool, a throat swab, or wounds. If yersiniosis is suspected, notify the clinical laboratory because cold enrichment, alkali treatment, or plating of a clinical specimen on CIN agar can be used to increase the likelihood of a positive culture. Several culture-independent diagnostic tests (CIDTs) are now available and have more than doubled the detection rate of Yersinia spp. in the United States. CIDT panels typically target only Y. enterocolitica, and the rarity of yersiniosis has precluded robust evaluation of the specificity and sensitivity of CIDT platforms through prospective studies. Culture is required to determine the species and for antimicrobial susceptibility testing. For questions about diagnostic testing beyond the capacity of the clinical laboratory, contact a local or state public health department. Public health officials can provide information and guidance on specimen submission, including submission to the Centers for Disease Control and Prevention (CDC) if appropriate.

Treatment

Most infections are self-limited. Antimicrobial drug therapy has not been shown to shorten the duration of uncomplicated enterocolitis or to alter the likelihood of postinfectious sequelae. Prescribe antibiotics for moderate to severe illness. Y. enterocolitica isolates are usually susceptible to aminoglycosides, third-generation cephalosporins, fluoroquinolones, tetracyclines, and trimethoprim-sulfamethoxazole and are typically resistant to first-generation cephalosporins and most penicillins.

Prevention

Travelers can reduce the risk for Yersinia spp. infection by avoiding consumption of unpasteurized milk products, raw or undercooked pork products, and untreated water (see Sec. 2, Ch. 8, Food & Water Precautions). Washing hands with soap and water before eating and preparing food, after contact with animals, and after handling raw meat helps reduce risk.

CDC website: Yersiniosis