National outbreak of Salmonella typhimurium with preference for infants

Purpose: During a large outbreak of Salmonella typhimurium (S. typhimurium) in Denmark in 2008, a remarkable high incidence was observed among children below the age of 1 year. Therefore we performed this retrospective study to describe the epidemiology, severity and outcome among a subset of children in this age-group. Methods: Cases were identified for the years 2000-2009 through a register at the Department of Clinical Microbiology at Hvidovre Hospital, in the Copenhagen area, Denmark. For hospitalized patients below 1 year with S. typhimurium, the medical record was reviewed. Results: The highest incidence for S. typhimurium was observed in 2008 with 315 cases per 100,000 among children below 1 year. In 2008 significantly more children age <6 months were admitted to the hospital compared to infants 6 12 months. The duration of symptoms before admittance was shorter among the infants in 2008, compared to the group consisting of infants in other years 20002009 (p = 0.04). None of the children had bacteremia or meningitis, and none of the children died. Conclusion: During the S. typhimurium outbreak in 2008, the incidence was especially high among infants age under 1 year. The infants in 2008 might have been slightly more affected than other years 2000-2009.