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Legionella and Legionnaires’ Disease

What should you do if an employee or occupant at your facility is diagnosed with Legionnaires’ disease or Pontiac fever? How would you respond? Who should be involved? A methodical approach to this situation is crucial. If there is a confirmed case of Legionnaires’ disease, or worse, a death, it is essential to have a plan that addresses all of the issues.

It is best to have a written, well-thought-out plan in advance of any health-related issue; however, with Legionnaires’ disease it is critical. Whenever there is a case of Legionnaires’ disease or Pontiac fever, the essential steps to reduce the potential for additional cases and to respond to the immediate issues include the following:

  • Shut off drinking-water supplies; use bottled water
  • Shutdown outdoor air intakes if there are cooling towers
  • Consult with a physician to assess specific risk factors in other occupants such as the elderly, smokers and immuno-compromised individuals
  • Consult with an industrial hygienist with significant expertise in Legionella assessments
  • Have the industrial hygienist conduct a walk-through survey to identify potential Legionella bacteria reservoirs and pathways for potential exposure
  • Develop a sampling plan and collect water samples for Legionella analysis using PCR and culturable methodologies
  • Address human resource needs and facility-related issues
  • Evaluate hot water temperatures
  • Evaluate the current treatment and maintenance procedures for cooling towers and for water distribution and storage systems
  • Have the industrial hygienist review laboratory data with medical and facilities components
  • Design and implement treatment options based on laboratory results and water sources found to be positive for the Legionella bacteria
  • Conduct follow-up sampling after treatment and following any plumbing modifications
  • Develop a Legionella control plan
  • Conduct annual audits of the plan’s effectiveness

Here are a few facts worth remembering:

  • Legionella bacteria are naturally occurring and can be found in outdoor water sources
  • Legionella bacteria grow best in warm water, typically 95 to 110 degrees Fahrenheit
  • Just one colony of Legionella pneumophila bacteria in a drinking water system is a concern
  • There is no validated air sampling method for the Legionella bacteria
  • Treatment of water systems is not always effective due to slime layers, corrosion and sediment.

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