title: Seroincidence of non-typhoid Salmonella infections: convenience vs. random community-based sampling.
abstract: The incidence of reported infections of non-typhoid Salmonella is affected by biases inherent to passive laboratory surveillance, whereas analysis of blood sera may provide a less biased alternative to estimate the force of Salmonella transmission in humans. We developed a mathematical model that enabled a back-calculation of the annual seroincidence of Salmonella based on measurements of specific antibodies. The aim of the present study was to determine the seroincidence in two convenience samples from 2012 (Danish blood donors, n = 500, and pregnant women, n = 637) and a community-based sample of healthy individuals from 2006 to 2007 (n = 1780). The lowest antibody levels were measured in the samples from the community cohort and the highest in pregnant women. The annual Salmonella seroincidences were 319 infections/1000 pregnant women [90% credibility interval (CrI) 210-441], 182/1000 in blood donors (90% CrI 85-298) and 77/1000 in the community cohort (90% CrI 45-114). Although the differences between study populations decreased when accounting for different age distributions the estimates depend on the study population. It is important to be aware of this issue and define a certain population under surveillance in order to obtain consistent results in an application of serological measures for public health purposes.
authors.affiliation: Department of Infectious Disease Epidemiology,Statens Serum Institut,Denmark.
authors.forename: H-D
authors.initials: HD
authors.lastname: Emborg
authors.affiliation: Department of Epidemiology Research,Statens Serum Institut,Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Simonsen
authors.affiliation: Department of Microbiological Diagnostics and Virology,Statens Serum Institut,Denmark.
authors.forename: C S
authors.initials: CS
authors.lastname: Jørgensen
authors.affiliation: Department of Clinical Immunology,Capital Region,Copenhagen University Hospital,Denmark.
authors.forename: L H
authors.initials: LH
authors.lastname: Harritshøj
authors.affiliation: Department of Microbiology and Infection Control,Statens Serum Institut,Denmark.
authors.forename: K A
authors.initials: KA
authors.lastname: Krogfelt
authors.affiliation: Research Centre for Prevention and Health,Glostrup University Hospital,Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Linneberg
authors.affiliation: Department of Infectious Disease Epidemiology,Statens Serum Institut,Denmark.
authors.forename: K
authors.identifier: http://orcid.org/0000-0002-3100-4990
authors.initials: K
authors.lastname: Mølbak
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012475:Salmonella / Q000302:isolation & purification*; D012480:Salmonella Infections / Q000453:epidemiology* / Q000382:microbiology; D016036:Seroepidemiologic Studies; D012698:Serologic Tests / Q000379:methods*; D055815:Young Adult
keywords: Salmonella; serology; surveillance