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Yersinia
Definition
Yersinia is a bacterium that can contaminate food
and is responsible for a foodborne disease called
yersiniosis.
Purpose
Yersinia is a serious issue because it contributes to
waterborne and foodborne diseases that each year
affect an estimated seventy-six million people in the
United States. Awareness of potential sources of food
contamination and knowledge of preventive measures
is an important factor for maintaining health.
Description
The genus Yersinia consists of 11 species of
gram-negative bacilli.Yersinia enterocolitica,Yersinia
pseudotuberculosis,andYersinia pestisare the three
disease-causing (pathogen) species.
Yersinia pestiscauses plague and people usually get
it from being bitten by a rodent flea that is a carrier or by
handling an infected animal. Millions of people in
Europe died from plague in the Middle Ages, carried
by flea-infested rats. Nowadays, antibiotics are used
effectively against plague, but if an infected person is
not treated promptly, the disease is likely to cause illness
or death. In the United States, the last plague epidemic
occurred in Los Angeles in 1924–25. Since then, plague
has occurred as a few scattered cases in rural areas, at an
average rate of 10 to 15 persons each year.
Fifteen pathogenic O groups ofY. enterocolitica
have been identified with serotype O:3 now predominat-
ing as the most common type in the United States.
Y. enterocoliticainfections are uncommon in the United
States. According to the Foodborne Disease Active Sur-
veillance Network (FoodNet), the annual incidence per
100,000 people is 9.6 for infants, 1.4 for young children,
and 0.2 for other age groups.Y. pseudotuberculosisinfec-
tions are even more rare.Y. enterocoliticais mostly found
in swine andY. pseudotuber-culosishas been reported in
deer,elk,goats,sheep,cattle,rats,squirrels,beaver,rab-
bits, and many bird species. To date however, no food-
borne outbreaks caused byY. pseudotuberculosishave
been reported in the United States.
Y. enterocoliticainfections cause yersiniosis, a
disease with a variety of symptoms depending on
the age of the person infected. In children, common
symptoms are fever, abdominal pain, and diarrhea,
which is often bloody. Yersinia infections are trans-
mitted by eating contaminated food, such as raw or
incompletely cooked pork products and unpasteur-
ized milk, by contaminatedwater, by contact with
infected animals, by transfusion with contaminated
blood, and rarely from person-to-person. The incu-
bation period usually varies between 4 to 6 days. The
exact cause of the food contamination is unknown,
but prevalence of the organism in the soil and water
and in animals such as beavers, pigs, and squirrels,
allows it to enter the food supply chain.Y. enter-
ocoliticaoutbreaks documented at the Center for
Disease Control (CDC) include:
1976: Chocolate milk outbreak in Oneida County,
NY. involving school children.
December 1981–February 1982: Outbreak in King
County, WA, caused by ingestion of tofu. Investiga-
tors from the Food and Drug Administration (FDA)
identified the source of the infection to be an non–
chlorinated water supply.
1982. Outbreaks in Arkansas, Tennessee, and Mis-
sissippi due to the consumption of pasteurized milk.
FDA investigators identified the infection source to
be contaminated milk containers.