Epidemiological comparison of international travel-associated and domestically acquired Campylobacter, Salmonella, and Shigella infections reported to Foodborne Diseases Active Surveillance Network (FoodNet), 2010-2019.

BACKGROUND

A 2004-2009 analysis found that 13% of enteric illnesses reported in the United States were associated with international travel, with >90% caused by Campylobacter, Salmonella, or Shigella. This analysis characterizes the epidemiology of travel-associated campylobacteriosis, salmonellosis, and shigellosis in the FoodNet catchment during 2010-2019.

METHODS

We analyzed FoodNet surveillance data for laboratory-confirmed infections during 2010-2019. Characteristics of travel-associated and domestically acquired infections were compared between world regions using incidence rate ratios (IRRs) and counterfactual random forest (CFRF) methods.

RESULTS

During 2010-2019, 61,397 Campylobacter, 63,823 Salmonella, and 19,141 Shigella infections were reported. Among people with known travel status, 16%, 11%, and 15% of Campylobacter, Salmonella, and Shigella infections were travel-associated. Incidence of travel-associated campylobacteriosis, salmonellosis and shigellosis increased from 2004 to 2009 to 2010-2014 and from 2010 to 2014 to 2015-2019. More travelers reported visiting Latin America and the Caribbean (2010-2014: 44%; 2015-2019: 45%) but illness incidence was highest among travelers to Africa (2010-2014: 49.8 per 100,000; 2015-2019: 57.8 per 100,000). Demographic and clinical characteristics of people with travel-associated versus domestically acquired infections differed consistently across the three illnesses. Odds of reporting international travel were higher among urban versus rural residents, among people with mild versus severe illness, and among people diagnosed using culture-independent versus culture-based tests.

CONCLUSIONS

These findings underscore the importance of collecting travel history during clinical encounters and enteric disease investigations. Findings can help inform public health messaging and enteric disease prevention strategies provided to international travelers.