Surveillance Results
In 2007, a total of 17,883 laboratory-confirmed cases of infection in FoodNet surveillance areas were identified. The number of cases and incidence per 100,000 population were reported as follows: Salmonella (6,790; 14.92), Campylobacter (5,818; 12.79), Shigella (2,848; 6.26), Cryptosporidium (1,216; 2.67), STEC O157 (545; 1.20), STEC non-O157 (260; 0.57), Yersinia (163; 0.36), Listeria (122; 0.27), Vibrio (108; 0.24), and Cyclospora (13; 0.03). Substantial variation occurred across surveillance sites. The highest incidence per 100,000 population for Salmonella (62.11), Shigella (27.77), Campylobacter (24.01), and STEC O157 (3.66) infections was among children aged <5 years. In 2006, FoodNet identified 82 cases of postdiarrheal HUS in persons aged <18 years (0.78 cases per 100,000 children); 58 (0.7%) cases occurred in children aged <5 years (2.01 cases per 100,000 children).
.png)
Of the 6,299 (92.8%) Salmonella isolates serotyped, seven serotypes accounted for 61.6% of infections: Enteritidis, 1,062 (16.9%); Typhimurium, 1,006 (16.0%); Newport, 656 (10.4%); I 4,[5],12:i:-, 358 (5.7%); Javiana, 347 (5.5%); Heidelberg, 243 (3.9%); and Montevideo, 211 (3.4%). Among 102 (94.4%) Vibrio isolates for which the species was identified, 59 (57.8%) were parahaemolyticus, 18 (17.7%) were alginolyticus, and 13 (12.8%) were vulnificus. Among 260 STEC non-O157 isolates tested for O antigen determination, 228 (87.7%) had an identifiable O antigen, primarily O26 (21.5%), O103 (20.6%), or O121 (19.3%).
In 2008, a total of 18,499 laboratory-confirmed cases of infection in FoodNet surveillance areas were identified. The number of infections and incidence per 100,000 population were reported as follows: Salmonella (7,444; 16.20), Campylobacter (5,825; 12.68), Shigella (3,029; 6.59), Cryptosporidium (1,036; 2.25), STEC O157 (513; 1.12), STEC non-O157 (205; 0.45), Yersinia (164; 0.36), Listeria (135; 0.29), Vibrio (131; 0.29), and Cyclospora (17; 0.04). Substantial variation in incidence rates occurred among surveillance area. Among all age groups (<4 years, 4–11 years, 12–19 years, 20–49 years, and >50 years)†, the highest incidence occurred among children aged <4 years for all infections except those caused by Cyclospora and Vibro.
.png)
Among age groups of persons infected with the following pathogens, the percentage of persons hospitalized was highest in persons aged >50 years: Listeria (86.2%), STEC O157 (53.3%), Vibrio (45.6%), Salmonella (40.0%), Yersinia (37.5%), Shigella (27.9%), Cryptosporidium (24.5%), and Campylobacter (20.5%). Among age groups of persons infected with the following pathogens, the case fatality rate (CFR) was highest in persons aged >50 years: Listeria (19.5%), Vibrio (7.4%), Salmonella (1.3%), Shigella (0.4%), and Campylobacter (0.4%). For infection with STEC O157, the CFR was highest among children aged <4 years (2.8%); for infection with Cryptosporidium and Yersinia, the CFR was highest in persons aged 20–49 years (1.3% and 3.0%, respectively).
Among 6,750 (91%) Salmonella isolates serotyped, 10 serotypes accounted for 73% of infections: Enteritidis, 1,356 (20.1%); Typhimurium, 1,077 (16.0%); Newport, 681 (10.1%); Javiana, 423 (6.3%); Saintpaul, 403 (6.0%); I 4,[5],12:i:-, 269 (4.0%); Muenchen, 213 (3.2%); Heidelberg, 198 (2.9%); Montevideo, 194 (2.9%); and Braenderup, 108 (1.6%). Among 131 (92%) Vibrio isolates for which the species was identified, 72 (55.0%) were parahaemolyticus, 19 (14.5%) were vulnificus, and eight (6.1%) were alginolyticus. Among 205 STEC non-O157 isolates tested for O antigen determination, 185 (90%) had an identifiable O antigen, most commonly O26 (28.1%), O103 (27.0%), or O111 (19.5%).
Outbreak-Associated Cases of Infection
In 2007, outbreak-associated infections accounted for 86 (15.8%) of STEC O157 cases and 364 (5.4%) of Salmonella cases ascertained, similar to proportions in previous years. Four large multistate outbreaks of Salmonella infections that included FoodNet sites were investigated in 2007: an outbreak of S. Tennessee infections caused by contaminated peanut butter, an outbreak of S. I 4,[5],12:i:- infections caused by contaminated frozen pot pies, an outbreak of S. Wandsworth and S. Typhimurium infections attributed to a puffed vegetable snack, and an outbreak of S. Paratyphi B var. Java associated with exposure to turtles.
In 2008, outbreak-associated infections accounted for 132 (25.7%) of STEC O157 cases and 547 (7.4%) of Salmonella cases. Two large multistate outbreaks of Salmonella infections that included FoodNet sites were investigated in 2008: an outbreak of S. Saintpaul infections associated with imported produce and an outbreak of S. Typhimurium infections associated with peanut butter and peanut butter–containing products.