title: An outbreak of influenza in a residential drug-rehabilitation community.
abstract: Influenza outbreaks can be difficult to control in confined settings where high-risk individuals are concentrated. Following the occurrence of a large number of cases of influenza-like illness in a rehabilitation community for drug users, between February and March 2004, surveillance activities were implemented. Attack rates of influenza-like illness were calculated, and risk factors for the development of disease and complications were evaluated through the use of relative risks (RR) with 95% confidence intervals (CI). Nasal-pharyngeal samples were collected for virological studies. Of 1,310 persons who were living in the community, 209 were diagnosed with influenza-like illness: the attack rate (15.9% overall) was higher for HIV-infected persons (RR: 1.77, 95% CI: 1.32-2.37), older individuals, and dormitory residents. HIV-infected participants were also more likely to develop complications compared with HIV-uninfected persons diagnosed with influenza-like illness (RR: 5.13, 95% CI: 2.52-10.20). The outbreak was attributable to Christchurch-like influenza A strains. Vaccination was ineffective because of the mismatch between wild and vaccine strains.
authors.affiliation: Medical Center, San Patrignano Community, Rimini, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Boschini
authors.forename: Benedetta
authors.initials: B
authors.lastname: Longo
authors.forename: Francesca
authors.initials: F
authors.lastname: Caselli
authors.forename: Marco
authors.initials: M
authors.lastname: Begnini
authors.forename: Cesare
authors.initials: C
authors.lastname: De Maria
authors.forename: Filippo
authors.initials: F
authors.lastname: Ansaldi
authors.forename: Paolo
authors.initials: P
authors.lastname: Durando
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Icardi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Rezza
mesh_terms: D000328:Adult; D000367:Age Factors; D016001:Confidence Intervals; D004196:Disease Outbreaks; D005260:Female; D015658:HIV Infections; D006801:Humans; D009980:Influenza A virus / Q000235:genetics; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D007558:Italy / Q000453:epidemiology; D008297:Male; D010802:Phylogeny; D012307:Risk Factors; D016320:Substance Abuse Treatment Centers