Legionnaire's Disease is caused by more than forty species of Legionella bacteria, with Legionella Pneumophila being the most common. This naturally occurring bacteria can be found in natural bodies of water but, more importantly, it can be found in building water systems such as hot-water heaters, sinks, showers, cooling towers, spas, nebulizers, air conditioners, etc.

Legionnaire's Disease is generally contracted through inhalation of airborne water droplets that contain the bacteria. The water containing the bacteria is misted by a shower, cooling tower, HVAC system, etc., and inhaled by people within the vicinity of the source.

Legionella bacteria can survive in water that ranges from 68^oF to 122^oF and grow in temperatures ranging from 77^oF to 108^oF, which means that domestic and commercial hot-water systems are within the prime range to support the growth of Legionella bacteria. And, while hot temperatures are ideal for bacteria preservation and growth, there have even been samples collected from cold-water systems, including the domestic cold-water intake, that have confirmed the presence of Legionella bacteria.

Legionellosis is commonly mistaken for pneumonia as the symptoms are very similar. The symptoms usually include, but are not limited to; fever, chills, cough, muscle pain, headaches, and diarrhea. Symptoms may appear anywhere from two to fourteen days after the exposure. Legionellosis is generally confirmed in a person through a blood test and urine antigen test.

Emergency Investigations

When a case of Legionellosis is confirmed via medical testing, the local Department of Health (DOH) generally recommends an emergency investigation of the facility, which can be very expensive. The investigation team includes the facility owner, the DOH, and an environmental consultant. As part of the investigation, the team inspects all of the water systems in the affected facility in an effort to determine possible pathways. Certain DOHs will also require bulk water sampling of 10% of the water sources (i.e. each faucet, shower, spas, whirlpools, cooling towers, etc.). The Occupational Health and Safety Administrations (OSHA) guideline is less than 1 Colony-Forming Unit per milliliter. Since Legionella bacteria is naturally occurring, it is likely that some of the results will be above the OSHA guideline.

Taking the Right Proactive Steps

Facilities that house a population susceptible to Legionellosis, such as healthcare facilities, nursing homes, jails, office buildings, and to some extent Housing Authorities, should perform some proactive investigation of their facilities as a means of identifying potential problems prior to any identified case of Legionellosis.

Facilities may choose to inspect the water systems to identify conditions that could be indicative of or could be contributing to the growth of Legionella bacteria, such as dead legs, insufficient chlorine residuals, unsanitary conditions, etc. As part of this investigation, bulk water and/or swab sampling may be conducted. Upon the completion of the investigation, the development of some protocol or system maintenance should be instituted to abate conditions that are conducive to supporting Legionella bacteria growth.

If your facility is at risk, there are a number of professional assessments and practices that will aid in the early detection and control of legionella bacteria:

• Targeted facility site inspections to evaluate potential systems that may contribute to legionella growth.
• Development of Best Practices to prevent and or eliminate the future growth of Legionella.
• Legionella sampling.
• Implementation of water-treatment systems to reduce Legionella bacteria within the water system.
  

Importantly, make sure you engage a consultant with direct expertise and experience in the identification of legionella sources and in the design of management plans and systems to control and eliminate the potential growth of legionella bacteria. Working closely with the DOH will help your consultant to quickly identify the potential source of the concern, and development effective strategies to address it. Please feel free to contact me with any questions or concerns you have about Legionella risk or control programs.