title: Household transmission of pandemic (H1N1) 2009, San Antonio, Texas, USA, April-May 2009.
abstract: To assess household transmission of pandemic (H1N1) 2009 in San Antonio, Texas, USA, during April 15-May 8, 2009, we investigated 77 households. The index case-patient was defined as the household member with the earliest onset date of symptoms of acute respiratory infection (ARI), influenza-like illness (ILI), or laboratory-confirmed pandemic (H1N1) 2009. Median interval between illness onset in index and secondary case-patients was 4 days (range 1-9 days); the index case-patient was likely to be < or =18 years of age (p = 0.034). The secondary attack rate was 4% for pandemic (H1N1) 2009, 9% for ILI, and 13% for ARI. The secondary attack rate was highest for children <5 years of age (8%-19%) and lowest for adults > or =50 years of age (4%-12%). Early in the outbreak, household transmission primarily occurred from children to other household members and was lower than the transmission rate for seasonal influenza.
authors.affiliation: Centers for Disease Control and Prevention, 1600 Clifton Rd NE, Mailstop C12, Atlanta, GA 30333, USA. omorgan@cdc.gov
authors.forename: Oliver W
authors.initials: OW
authors.lastname: Morgan
authors.forename: Sharyn
authors.initials: S
authors.lastname: Parks
authors.forename: Trudi
authors.initials: T
authors.lastname: Shim
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Blevins
authors.forename: Pauline M
authors.initials: PM
authors.lastname: Lucas
authors.forename: Roger
authors.initials: R
authors.lastname: Sanchez
authors.forename: Nancy
authors.initials: N
authors.lastname: Walea
authors.forename: Fleetwood
authors.initials: F
authors.lastname: Loustalot
authors.forename: Mark R
authors.initials: MR
authors.lastname: Duffy
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Shim
authors.forename: Sandra
authors.initials: S
authors.lastname: Guerra
authors.forename: Fernando
authors.initials: F
authors.lastname: Guerra
authors.forename: Gwen
authors.initials: G
authors.lastname: Mills
authors.forename: Jennifer
authors.initials: J
authors.lastname: Verani
authors.forename: Bryan
authors.initials: B
authors.lastname: Alsip
authors.forename: Stephen
authors.initials: S
authors.lastname: Lindstrom
authors.forename: Bo
authors.initials: B
authors.lastname: Shu
authors.forename: Shannon
authors.initials: S
authors.lastname: Emery
authors.forename: Adam L
authors.initials: AL
authors.lastname: Cohen
authors.forename: Manoj
authors.initials: M
authors.lastname: Menon
authors.forename: Alicia M
authors.initials: AM
authors.lastname: Fry
authors.forename: Fatimah
authors.initials: F
authors.lastname: Dawood
authors.forename: Vincent P
authors.initials: VP
authors.lastname: Fonseca
authors.forename: Sonja J
authors.initials: SJ
authors.lastname: Olsen
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000998:Antiviral Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005191:Family Characteristics; D005260:Female; D006801:Humans; D055256:Infectious Disease Incubation Period; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000188:drug therapy / Q000453:epidemiology / Q000635:transmission*; D008297:Male; D008875:Middle Aged; D053139:Oseltamivir / Q000627:therapeutic use; D013781:Texas / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000998:Antiviral Agents; D053139:Oseltamivir