title: US outbreak of human Salmonella infections associated with aquatic frogs, 2008-2011.
abstract: OBJECTIVE
  Although amphibians are known Salmonella carriers, no such outbreaks have been reported. We investigated a nationwide outbreak of human Salmonella Typhimurium infections occurring predominantly among children from 2008 to 2011.
  
  
  METHODS
  We conducted a matched case-control study. Cases were defined as persons with Salmonella Typhimurium infection yielding an isolate indistinguishable from the outbreak strain. Controls were persons with recent infection with Salmonella strains other than the outbreak strain and matched to cases by age and geography. Environmental samples were obtained from patients' homes; traceback investigations were conducted.
  
  
  RESULTS
  We identified 376 cases from 44 states from January 1, 2008, to December 31, 2011; 29% (56/193) of patients were hospitalized and none died. Median patient age was 5 years (range <1-86 years); 69% were children <10 years old (253/367). Among 114 patients interviewed, 69 (61%) reported frog exposure. Of patients who knew frog type, 79% (44/56) reported African dwarf frogs (ADF), a type of aquatic frog. Among 18 cases and 29 controls, illness was significantly associated with frog exposure (67% cases versus 3% controls, matched odds ratio 12.4, 95% confidence interval 1.9-infinity). Environmental samples from aquariums containing ADFs in 8 patients' homes, 2 ADF distributors, and a day care center yielded isolates indistinguishable from the outbreak strain. Traceback investigations of ADFs from patient purchases converged to a common ADF breeding facility. Environmental samples from the breeding facility yielded the outbreak strain.
  
  
  CONCLUSIONS
  ADFs were the source of this nationwide pediatric predominant outbreak. Pediatricians should routinely inquire about pet ownership and advise families about illness risks associated with animals.
authors.affiliation: Epidemic Intelligence Service, National Center for Emerging Zoonotic and Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. smettee@cdc.gov
authors.forename: Shauna L
authors.initials: SL
authors.lastname: Mettee Zarecki
authors.forename: Sarah D
authors.initials: SD
authors.lastname: Bennett
authors.forename: Julia
authors.initials: J
authors.lastname: Hall
authors.forename: Jill
authors.initials: J
authors.lastname: Yaeger
authors.forename: Kate
authors.initials: K
authors.lastname: Lujan
authors.forename: Marguerite
authors.initials: M
authors.lastname: Adams-Cameron
authors.forename: Kim
authors.initials: K
authors.lastname: Winpisinger Quinn
authors.forename: Rita
authors.initials: R
authors.lastname: Brenden
authors.forename: Gwen
authors.initials: G
authors.lastname: Biggerstaff
authors.forename: Vincent R
authors.initials: VR
authors.lastname: Hill
authors.forename: Kari
authors.initials: K
authors.lastname: Sholtes
authors.forename: Nancy Marie
authors.initials: NM
authors.lastname: Garrett
authors.forename: Patti C
authors.initials: PC
authors.lastname: Lafon
authors.forename: Casey
authors.initials: C
authors.lastname: Barton Behravesh
authors.forename: Samir V
authors.initials: SV
authors.lastname: Sodha
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D016358:Contact Tracing; D004196:Disease Outbreaks; D004199:Disease Vectors; D005260:Female; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D057805:Pets / Q000382:microbiology*; D010884:Pipidae / Q000382:microbiology*; D012189:Retrospective Studies; D012480:Salmonella Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000635:transmission; D012486:Salmonella typhimurium / Q000302:isolation & purification*; D014481:United States / Q000453:epidemiology; D055815:Young Adult