title: The serotype case-case design: a direct comparison of a novel methodology with a case-control study in a national Salmonella Enteritidis PT14b outbreak in England and Wales.
abstract: Societal and technological changes render traditional study designs less feasible for investigation of outbreaks. We compared results obtained from case-case and case-control designs during the investigation of a Salmonella Enteritidis PT14b (SE14b) outbreak in Britain to provide support for validation of this approach. Exposures of cases were compared to concurrent non-Enteritidis Salmonella cases and population controls recruited through systematic digit phone dialling. Infection with SE14b was associated with eating in oriental restaurants [odds ratio (OR) 35·8, 95% confidence interval (CI) 4·4-290·9] and consuming eggs away from home (OR 13·8, 95% CI 1·5-124·5) in the case-case study and was confirmed through a concurrent case-control study with similar effect estimates and microbiological findings of SE14b in eggs from a specific chicken flock on a Spanish farm. We found that the case-case design was feasible, quick and inexpensive, potentially minimized recall bias and made use of already interviewed cases with subtyping results. This approach has potential for use in future investigations.
authors: Health Protection Services Colindale, Health Protection Agency, London, UK.
authors: D
authors: D
authors: Zenner
authors: K
authors: K
authors: Janmohamed
authors: C
authors: C
authors: Lane
authors: C
authors: C
authors: Little
authors: A
authors: A
authors: Charlett
authors: G K
authors: GK
authors: Adak
authors: D
authors: D
authors: Morgan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002648:Child; D004196:Disease Outbreaks; D004739:England / Q000453:epidemiology; D005260:Female; D005516:Food Microbiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D016017:Odds Ratio; D012107:Research Design; D012307:Risk Factors; D012480:Salmonella Infections / Q000453:epidemiology* / Q000382:microbiology; D012477:Salmonella enteritidis / Q000145:classification*; D014852:Wales / Q000453:epidemiology; D055815:Young Adult