Salmonella infections in Denmark from 2013–2022 with focus on serotype distribution, invasiveness, age, sex, and travel exposition
Nicholas Slinning Aarø, Mia Torpdahl, Torben Riis Rasmussen, Martin Jensen, Hans Linde Nielsen, The Danish Study Group for Enteric Infection has the following members, Ming Chen, Jørgen Engberg, Hanne Marie Holt, Lars Lemming, Lisbeth Lützen, Marc Trunjer Kusk Nielsen, Bente Olesen, Ingrid Maria Cecilia Rubin, Kristian Schønning
Abstract
PURPOSE: To analyze the nationwide incidence of Salmonella infections in Denmark from 2013 to 2022. METHODS: Confirmed cases of Salmonella enterica subsp. enterica were examined using the National Register of Enteric Pathogens during 2013-2022. Proportions, incidence rates (IR), relative risk (RR), and 95% confidence intervals (CI) were calculated to assess differences in serotypes, invasiveness, age, sex, and travel exposure. RESULTS: We identified 9,944 Danish Salmonella enterica subsp. enterica cases, with an average annual incidence rate of 16.9 per 100,000 inhabitants, declining during the COVID-19 pandemic. Typhoidal cases totaled 206, with an average annual IR of 0.35 per 100,000 inhabitants. Enteric fever patients had a median age of 24 years (IQR:17-36). Leading non-typhoid Salmonella (NTS) serotypes were S. Enteritidis (26.4%), monophasic S. Typhimurium (16.5%), and S. Typhimurium (13.5%). Median age for NTS cases was 42 (IQR: 18-62), with even sex distribution, and a third reported travel prior to onset of disease. The overall percentage of invasive NTS (iNTS) infection was 8.1% (CI: 7.6-8.7). Eleven serotypes were associated with higher invasiveness, with S. Dublin and S. Panama having the highest invasiveness with age and sex-adjusted RR of 7.31 (CI: 6.35-8.43) and 5.42 (CI: 3.42-8.60), respectively, compared to all other NTS serotypes. Increased age was associated with higher RR for iNTS infection. CONCLUSION: During the decade, there was a limited number of typhoidal cases. The dominant NTS serotypes were S. Enteritidis and monophasic S. Typhimurium, whereas S. Dublin and S. Panama exhibited the highest invasive potential.