Salmonella Infections Associated with International Travel: A Foodborne Diseases Active Surveillance Network (FoodNet) Study

Abstract

Salmonella species cause an estimated 1.2 million infections per year in the United States, making it one of the most commonly reported enteric pathogens. In addition, Salmonella is an important cause of travel-associated diarrhea and enteric fever, a systemic illness commonly associated with Salmonella serotypes Typhi and Paratyphi A. We reviewed cases of Salmonella infection reported to the Centers for Disease Control and Prevention's (CDC) Foodborne Diseases Active Surveillance Network (FoodNet), a sentinel surveillance network, from 2004 to 2008. We compared travelers with Salmonella infection to nontravelers with Salmonella infection with respect to demographics, clinical characteristics, and serotypes. Among 23,712 case-patients with known travel status, 11% had traveled internationally in the 7 days before illness. Travelers with Salmonella infection tended to be older (median age, 30 years) than nontravelers (median age, 24 years; p<0.0001), but were similar with respect to gender. The most common destinations reported were Mexico (38% of travel-associated infections), India (9%), Jamaica (7%), the Dominican Republic (4%), China (3%), and the Bahamas (2%). The proportions of travelers with Salmonella infection hospitalized and with invasive disease were inversely related to the income level of the destination (p<0.0001). The most commonly reported serotypes, regardless of travel status, were Enteritidis (19% of cases), Typhimurium (14%), Newport (9%), and Javiana (5%). Among infections caused by these four serotypes, 22%, 6%, 5%, and 4%, respectively, were associated with travel. A high index of clinical suspicion for Salmonella infection is appropriate when evaluating recent travelers, especially those who visited Africa, Asia, or Latin America.