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Legionnaires' disease outbreak in Murcia, Spain

Anna García-Fulgueiras1, Carmen Navarro, Daniel Fenoll

  • 1Regional Health Council of Murcia, Murcia, Spain. anam.garcia9@carm.es

Emerging Infectious Diseases
|September 12, 2003
PubMed

Insights

The 2001 Murcia outbreak, the world's largest Legionnaires' disease event, was traced to hospital cooling towers. Environmental and clinical isolates matched, confirming the source of this major public health incident.

Area of Science:

  • Public Health
  • Infectious Diseases
  • Epidemiology

Background:

  • Legionnaires' disease is a severe bacterial pneumonia caused by Legionella.
  • Outbreaks can occur when contaminated water aerosolizes, leading to widespread exposure.
  • Identifying outbreak sources is critical for public health interventions.

Purpose of the Study:

  • To investigate the cause of a large Legionnaires' disease outbreak in Murcia, Spain, in July 2001.
  • To identify the specific source of the outbreak through epidemiologic and microbiologic methods.
  • To confirm the implicated source through molecular analysis.

Main Methods:

  • Conducted a large-scale outbreak investigation, including 600 epidemiologic questionnaires.
  • Performed a case-control study matching 85 patients with two controls each.
  • Collected environmental samples, specifically from cooling towers, for microbiologic analysis.

Main Results:

  • Confirmed 449 cases of Legionnaires' disease, with a 1% case-fatality rate.
  • Epidemiologic data indicated an outdoor point-source exposure in the northern part of Murcia.
  • Cooling towers at a city hospital were implicated, and environmental isolates matched clinical isolates.
  • Identified the largest Legionnaires' disease outbreak globally to date.

Conclusions:

  • The cooling towers of a city hospital were definitively identified as the source of the 2001 Murcia Legionnaires' disease outbreak.
  • The investigation highlighted the importance of environmental surveillance and rapid response in controlling large-scale infectious disease events.
  • This outbreak underscores the potential for Legionella transmission from engineered water systems.

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