ATLANTA — About 80% of Salmonella cases in the United States in 2004 and 2005 were domestically acquired isolated incidents, Dina Hoefer reported in a poster presented at the International Conference on Emerging Infectious Diseases.
In contrast, about 12% of infected patients with known travel status had traveled internationally, and almost 8% of cases were associated with a recognized outbreak, based on data from the Foodborne Diseases Active Surveillance Network (FoodNet).
FoodNet is a program supported by the CDC, the U.S. Department of Agriculture, and the FDA; it seeks to link foodborne illnesses to specific foods and settings based on data from 10 U.S. sites.
Ms. Hoefer, of the New York Department of Health in Albany, and her colleagues reviewed FoodNet surveillance data for 12,159 cases of Salmonella infection from 2004 and 2005. Of the 7,500 patients whose travel status and outbreak associations were known, 878 had traveled internationally within 7 days prior to illness onset, and 583 were known to be part of a documented Salmonella outbreak.
Overall, the isolated domestically acquired cases were significantly more likely to require hospitalization, compared with travel-related cases (relative risk 1.5) or cases associated with outbreaks (RR 1.4). The most common serotypes among all cases were S. enteritidis and S. typhimurium, but S. enteritidis accounted for a significantly higher proportion of travel-related cases, compared with S. typhimurium (35% vs. 9%).
In addition, isolated domestically acquired cases were more likely than outbreak-associated cases but less likely than travel-related cases to have Salmonella isolates in the blood or cerebrospinal fluid.