title: Salmonella typhimurium infections associated with peanut products.
abstract: BACKGROUND
  Contaminated food ingredients can affect multiple products, each distributed through various channels and consumed in multiple settings. Beginning in November 2008, we investigated a nationwide outbreak of salmonella infections.
  
  
  METHODS
  A case was defined as laboratory-confirmed infection with the outbreak strain of Salmonella Typhimurium occurring between September 1, 2008, and April 20, 2009. We conducted two case-control studies, product "trace-back," and environmental investigations.
  
  
  RESULTS
  Among 714 case patients identified in 46 states, 166 (23%) were hospitalized and 9 (1%) died. In study 1, illness was associated with eating any peanut butter (matched odds ratio, 2.5; 95% confidence interval [CI], 1.3 to 5.3), peanut butter-containing products (matched odds ratio, 2.2; 95% CI, 1.1 to 4.7), and frozen chicken products (matched odds ratio, 4.6; 95% CI, 1.7 to 14.7). Investigations of focal clusters and single cases associated with nine institutions identified a single institutional brand of peanut butter (here called brand X) distributed to all facilities. In study 2, illness was associated with eating peanut butter outside the home (matched odds ratio, 3.9; 95% CI, 1.6 to 10.0) and two brands of peanut butter crackers (brand A: matched odds ratio, 17.2; 95% CI, 6.9 to 51.5; brand B: matched odds ratio, 3.6; 95% CI, 1.3 to 9.8). Both cracker brands were made from brand X peanut paste. The outbreak strain was isolated from brand X peanut butter, brand A crackers, and 15 other products. A total of 3918 peanut butter-containing products were recalled between January 10 and April 29, 2009.
  
  
  CONCLUSIONS
  Contaminated peanut butter and peanut products caused a nationwide salmonellosis outbreak. Ingredient-driven outbreaks are challenging to detect and may lead to widespread contamination of numerous food products.
authors.affiliation: National Center for Emerging and Zoonotic Infectious Diseases, Division of Foodborne, Waterborne and Environmental Diseases, Program Office for Scientific Education and Professional Development, Centers for Disease Control and Prevention, Atlanta, USA. ecavallaro@cdc.gov
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Cavallaro
authors.forename: Kashmira
authors.initials: K
authors.lastname: Date
authors.forename: Carlota
authors.initials: C
authors.lastname: Medus
authors.forename: Stephanie
authors.initials: S
authors.lastname: Meyer
authors.forename: Benjamin
authors.initials: B
authors.lastname: Miller
authors.forename: Clara
authors.initials: C
authors.lastname: Kim
authors.forename: Scott
authors.initials: S
authors.lastname: Nowicki
authors.forename: Shaun
authors.initials: S
authors.lastname: Cosgrove
authors.forename: David
authors.initials: D
authors.lastname: Sweat
authors.forename: Quyen
authors.initials: Q
authors.lastname: Phan
authors.forename: James
authors.initials: J
authors.lastname: Flint
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Daly
authors.forename: Jennifer
authors.initials: J
authors.lastname: Adams
authors.forename: Eija
authors.initials: E
authors.lastname: Hyytia-Trees
authors.forename: Peter
authors.initials: P
authors.lastname: Gerner-Smidt
authors.forename: Robert M
authors.initials: RM
authors.lastname: Hoekstra
authors.forename: Colin
authors.initials: C
authors.lastname: Schwensohn
authors.forename: Adam
authors.initials: A
authors.lastname: Langer
authors.forename: Samir V
authors.initials: SV
authors.lastname: Sodha
authors.forename: Michael C
authors.initials: MC
authors.lastname: Rogers
authors.forename: Frederick J
authors.initials: FJ
authors.lastname: Angulo
authors.forename: Robert V
authors.initials: RV
authors.lastname: Tauxe
authors.forename: Ian T
authors.initials: IT
authors.lastname: Williams
authors.forename: Casey Barton
authors.initials: CB
authors.lastname: Behravesh
mesh_terms: D010367:Arachis / Q000382:microbiology*; D016022:Case-Control Studies; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D005511:Food Handling; D005516:Food Microbiology; D006801:Humans; D016017:Odds Ratio; D012478:Salmonella Food Poisoning / Q000453:epidemiology* / Q000209:etiology; D012486:Salmonella typhimurium / Q000302:isolation & purification*; D014481:United States / Q000453:epidemiology