title: A pre-pandemic outbreak of triple-reassortant swine influenza virus infection among university students, South Dakota, 2008.
abstract: BACKGROUND
  After identifying a student with triple-reassortant swine influenza virus (SIV) infection and pig exposure at a livestock event, we investigated whether others were infected and if human-to-human transmission occurred.
  
  
  METHODS
  We conducted a cohort study and serosurvey among persons exposed to (1) event pigs, (2) other pigs, (3) the index case, and (4) persons without pig or index case exposure. Confirmed cases had respiratory specimens positive for SIV within 2 weeks of the index case's illness. Probable and suspected cases had illness and (1) exposure to any pig or (2) contact with a confirmed case preceding illness. Probable cases were seropositive. Suspected cases did not give serum samples.
  
  
  RESULTS
  Of 99 event pig-exposed students, 72 (73%) participated in the investigation, and 42 (42%) provided serum samples, of whom 17 (40%) were seropositive and 5 (12%) met case criteria. Of 9 students exposed to other pigs, 2 (22%) were seropositive. Of 8 index case-exposed persons and 10 without exposures, none were seropositive. Pig-exposed persons were more likely to be seropositive than persons without pig exposure (37% vs 0%, P < .01).
  
  
  CONCLUSIONS
  We identified an outbreak of human SIV infection likely associated with a livestock event; there was no evidence of human-to-human transmission.
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. fdawood@cdc.gov
authors.forename: Fatimah S
authors.initials: FS
authors.lastname: Dawood
authors.forename: Libo
authors.initials: L
authors.lastname: Dong
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.forename: Dianna M
authors.initials: DM
authors.lastname: Blau
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Peebles
authors.forename: Xiuhua
authors.initials: X
authors.lastname: Lu
authors.forename: Lori
authors.initials: L
authors.lastname: Wagers
authors.forename: Brett
authors.initials: B
authors.lastname: Oakland
authors.forename: Michael
authors.initials: M
authors.lastname: Zielenski
authors.forename: Russell
authors.initials: R
authors.lastname: Daly
authors.forename: Vickie
authors.initials: V
authors.lastname: Horan
authors.forename: Sabrina L
authors.initials: SL
authors.lastname: Swenson
authors.forename: Beverly J
authors.initials: BJ
authors.lastname: Schmitt
authors.forename: Kathy
authors.initials: K
authors.lastname: Hancock
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Katz
authors.forename: Carolyn
authors.initials: C
authors.lastname: Bridges
authors.forename: Lon
authors.initials: L
authors.lastname: Kightlinger
authors.forename: Lyn
authors.initials: L
authors.lastname: Finelli
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001483:Base Sequence; D015331:Cohort Studies; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology / Q000635:transmission / Q000821:virology*; D008297:Male; D008969:Molecular Sequence Data; D016865:Reassortant Viruses / Q000302:isolation & purification*; D012189:Retrospective Studies; D016036:Seroepidemiologic Studies; D013023:South Dakota / Q000453:epidemiology; D013334:Students; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000635:transmission / Q000821:virology*; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral