The descriptive epidemiology of yersiniosis: a multistate study, 2005-2011.

OBJECTIVES: Yersiniosis, a foodborne infection of zoonotic origin caused by the bacteria Yersinia enterocolitica and Yersinia pseudotuberculosis, is a reportable disease in 38 states. Both sporadic and foodborne outbreaks of yersiniosis have been reported in the U.S., with annual occurrence of an estimated 98,000 episodes of illness, 533 hospitalizations, and 29 deaths. We analyzed surveillance data from nine non-FoodNet-participating U.S. states during the period 2005-2011 to describe the epidemiology of this disease. METHODS: As part of a passive surveillance system, laboratory-confirmed cases of yersiniosis were reported to state health departments in Arizona, Illinois, Michigan, Missouri, Nebraska, North Carolina, South Carolina, Washington, and Wisconsin. We calculated overall, age-, and race-specific annual incidence rates per 100,000 population using 2010 Census data as the denominator. We used Poisson regression to examine seasonal variation and annual incidence trends by race, age group, and overall. RESULTS: The average annual incidence of yersiniosis was 0.16 cases per 100,000 population during 2005-2011. We observed a statistically significant decreasing annual trend of yersiniosis incidence among African Americans <5 years of age (p<0.01), whereas white people aged 19-64 years (p=0.08) and Hispanic people (p=0.05) had an overall increasing annual incidence of yersiniosis. We observed higher incidence during October-December (p<0.01) and January-March (p=0.03) quarters among African Americans, whereas white people had a higher incidence during April-June (p=0.05). CONCLUSION: This multistate analysis revealed differences in the epidemiology of yersiniosis by race/ethnicity that may be useful for future research and prevention efforts. While this study was consistent with the FoodNet report in recognizing the high and declining incidence among African American children and winter seasonality among African Americans, our study also identified April-June seasonality among the white population.

Changing epidemiology of Yersinia enterocolitica infections: markedly decreased rates in young black children, Foodborne Diseases Active Surveillance Network (FoodNet), 1996-2009.

BACKGROUND: Yersinia enterocolitica causes an estimated 116,716 illnesses annually in the United States. Black children have historically had the highest rates of infection, with incidence peaking in the winter. METHODS: The Foodborne Diseases Active Surveillance Network (FoodNet) conducts active surveillance for laboratory-confirmed Y. enterocolitica infections, defined as the isolation of Y. enterocolitica or unspeciated Yersinia from a human clinical specimen. We calculated the average annual crude incidence rate per 100,000 persons from 1996 through 2009 and described rates by age, race, and geographic site. To account for changes in the FoodNet catchment area, we used a negative binomial model to estimate statistical changes in incidence using the average annual incidence in 1996-1998 as the baseline. RESULTS: From 1996 through 2009, 2085 Y. enterocolitica infections were reported to FoodNet. The average annual crude incidence was 0.5 per 100,000 persons and was highest in blacks (0.9 per 100,000 persons). Over time, the rate in blacks declined from 3.9 to 0.4 per 100,000 persons. Declines among other racial groups were not as pronounced. The largest decline occurred in black children <5 years old (from 41.5 per 100,000 persons in 1996 to 3.5 per 100,000 persons in 2009). From 2007 through 2009, the highest rate of infection was in Asian children (5.1 per 100,000 persons). Compared with 1996-1998, the incidence in 2009 was 66% (95% confidence interval, 51%-77%) lower among children <5 years old. CONCLUSIONS: Y. enterocolitica infections in FoodNet sites have significantly declined since 1996. These declines were greatest in young black children, the group that initially had the highest incidence, possibly as the result of educational efforts in Georgia.

Population-based surveillance for Yersinia enterocolitica infections in FoodNet sites, 1996-1999: higher risk of disease in infants and minority populations.

Active surveillance for laboratory-confirmed Yersinia enterocolitica (YE) infections was conducted at 5 Foodborne Diseases Active Surveillance Network (FoodNet) sites in the United States during 1996-1999. The annual incidence averaged 0.9 cases/100,000 population. After adjusting for missing data, the average annual incidence by race/ethnicity was 3.2 cases/100,000 population among black persons, 1.5 cases/100,000 population among Asian persons, 0.6 cases/100,000 population among Hispanic persons, and 0.4 cases/100,000 population among white persons. Incidence increased with decreasing age in all race/ethnicity groups. Black infants had the highest incidence (141.9 cases/100,000 population; range, 8.7 cases/100,000 population in Minnesota to 207.0 cases/100,000 population in Georgia). Seasonal variations in incidence, with a marked peak in December, were noted only among black persons. YE infections should be suspected in black children with gastroenteritis, particularly during November-February. Culturing for YE should be part of routine testing of stool specimens by clinical laboratories serving populations at risk, especially during the winter months.

Yersinia enterocolitica O:3: an emerging cause of pediatric gastroenteritis in the United States. The Yersinia enterocolitica Collaborative Study Group.

After an outbreak of Yersinia enterocolitica infections among black children in Atlanta, a seven-hospital study was conducted to determine the importance of this pathogen in other communities with large black populations. Of 4841 stool specimens from patients with gastroenteritis examined between November 1989 and January 1990, Y. enterocolitica, Shigella, Campylobacter, and Salmonella were identified in 38, 49, 60, and 98 specimens, respectively; 34 (92%) of 37 Y. enterocolitica isolates were serotype O:3. Of the 38 patients with yersiniosis, 37 (97%) were children. Illnesses were clustered around the holidays, and 20 (62%) of 32 patients had been exposed to raw pork intestines in the 2 weeks before onset. Exposure was significantly associated with illness in a case-control study of eight patients identified at one hospital (P = .004). Infants less than or equal to 6 months old with yersiniosis were more likely to have immature-to-total neutrophil ratios greater than 0.50 than were infants of comparable age with salmonellosis (P = .02). Infrequently isolated in the past, Y. enterocolitica O:3 is emerging as an important enteric pathogen in this country, particularly among black children.