Yersiniosis is a diarrheal illness caused by infection with Yersinia enterocolitica, a type of bacterium that is carried by some animals, mainly pigs. Yersiniosis can also be caused by infection with a bacterium called Yersinia pseudotuberculosis, but that is less common in the United States. Yersiniosis is not common in the United States. Approximately 50 cases are reported each year in California, but there may be more unreported cases in people who did not seek medical care or did not submit fecal specimens for testing. Young children are the most likely to get yersiniosis. Yersiniosis is more common in winter than in summer.
Most infections with Y. enterocolitica are caused by eating raw or undercooked pork products, or by drinking contaminated raw (unpasteurized) milk or untreated water. Infants can be infected if their caretakers handle raw pork intestines called chitterlings or “chitlins” and then do not wash their hands thoroughly before handling the infant or the infant’s toys, bottles, or pacifiers.