An outbreak of influenza in a residential drug-rehabilitation community

Antonio Boschini, Benedetta Longo, Francesca Caselli, Marco Begnini, Cesare De Maria, Filippo Ansaldi, Paolo Durando, Giancarlo Icardi, Giovanni Rezza

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)1218-1222
Number of pages5
JournalJournal of Medical Virology
Issue number9
Publication statusPublished - Sept 2006


  • HIV
  • Influenza
  • Injecting drug users
  • Outbreak investigation
  • Risk factors

ASJC Scopus subject areas

  • Virology


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