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.

Strategies for surveillance of pediatric hemolytic uremic syndrome: Foodborne Diseases Active Surveillance Network (FoodNet), 2000-2007.

BACKGROUND: Postdiarrheal hemolytic uremic syndrome (HUS) is the most common cause of acute kidney failure among US children. The Foodborne Diseases Active Surveillance Network (FoodNet) conducts population-based surveillance of pediatric HUS to measure the incidence of disease and to validate surveillance trends in associated Shiga toxin-producing Escherichia coli (STEC) O157 infection. METHODS: We report the incidence of pediatric HUS, which is defined as HUS in children <18 years. We compare the results from provider-based surveillance and hospital discharge data review and examine the impact of different case definitions on the findings of the surveillance system. RESULTS: During 2000-2007, 627 pediatric HUS cases were reported. Fifty-two percent of cases were classified as confirmed (diarrhea, anemia, microangiopathic changes, low platelet count, and acute renal impairment). The average annual crude incidence rate for all reported cases of pediatric HUS was 0.78 per 100,000 children <18 years. Regardless of the case definition used, the year-to-year pattern of incidence appeared similar. More cases were captured by provider-based surveillance (76%) than by hospital discharge data review (68%); only 49% were identified by both methods. CONCLUSIONS: The overall incidence of pediatric HUS was affected by key characteristics of the surveillance system, including the method of ascertainment and the case definitions. However, year-to-year patterns were similar for all methods examined, suggesting that several approaches to HUS surveillance can be used to track trends.