What is Legionella?

Legionella is a Gram-negative, rod-shaped bacterium that can cause pneumonia (Legionnaires’ disease) or a flu-like illness (Pontiac fever). It was first identified and recognized as causing disease during the outbreak that occurred in conjunction with the American Legion Convention in Philadelphia in 1976. There are over 50 species of Legionella and 18 of those can cause disease.

Illustration of Legionella under a microscope.

What actions should be taken if we find Legionella?

There is no known safe level of Legionella in building water systems. Cases of Legionnaires’ disease have been associated with very low levels of Legionella in building water systems.2 The intent of a water management program should be to manage building water systems to reduce hazardous conditions that allow Legionella to grow. If the team decides to incorporate routine environmental sampling for Legionella as part of their water management program, they will need to decide how and when to respond if these bacteria are found in their water systems.

If the team finds Legionella during routine environmental sampling (in the absence of disease), CDC suggests exploring possible reasons for the growth. Corrective actions, such as adjusting temperature levels or flushing the pipes, might be sufficient. Additional actions may be necessary if there are concerning trends (e.g., persistently positive samples at a single location, positive samples in a central distribution point, positive samples in multiple points-of-use, diversity in the types of Legionella detected).

The CDC and ASHRAE Guideline 12 provide general guidance on result interpretation and recommendations for action levels. In the absence of local or State regulations the published threshold guidelines provide a reference for water risk management teams to set action levels.

To find out more about how NoVA Environmental Solutions can help with your Water Management Program and Legionella Testing CALL US or Request More Information. We are here to help.

Bacteria Testing

Legionella Testing in Northern Virginia

NoVA Environmental Solutions provides facility managers with routine testing for Legionalla and other water-born bacteria.

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If your facility has a water management program in place, NoVA Environmental Solutions works with your team by providing routine environmental sampling for Legionella, which is performed proactively as part of an effort to reduce risk of Legionella growth and transmission in your buildings water systems.

While working with your team, we help make specific decisions about sampling frequency, location, and methodology. Sampling plans are unique to each facility and based on factors such as:

  • Findings from the environmental assessment and any baseline Legionella test results
  • Overall performance of the water management program, trend analysis of Legionella test results, and water quality parameters (e.g., disinfectant, temperature)
  • In healthcare facilities, correlation of environmental test results with clinical surveillance data
  • Building characteristics (e.g., size, age, complexity, populations served)
    Sites of possible exposure to aerosolized water
  • Available resources and supplies to support sampling

Sampling approaches can be adjusted over time based on trend data and system changes. Organizing these data in a format that is sortable by date, location, and result can be helpful when trying to analyze trends over time.

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