The American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) is currently in the process of converting its guideline entitled "Minimizing the Risk of Legionellosis Associated with Building Water Systems" (ASHRAE Guideline 12-2000) into an official standard. The standard will be designated "SPC 188." A draft – intended for public comment – is expected to be circulated by the ASHRAE Standards Project Committee before the end of this year. The conversion of the guideline into an official standard will carry much more weight in terms of what will be expected from non-residential and multi-residential building owners (e.g. hotels, hospitals, assisted living facilities, nursing homes, schools, etc.) to prevent Legionella in water handling systems. The current Legionella public health system in the United States is geared toward Legionellosis case reaction rather than affirmative action aimed at source prevention. When the final ASHRAE building standard is adopted, it will arguably result in an affirmative duty upon certain building owners to establish Legionella auditing and prevention programs.

Taking a more proactive approach to Legionella prevention may provide business and legal benefits. For example, an outbreak of Legionnaires' disease was recently discovered at Johns Hopkins Hospital's transplant building as a result of routine testing. The hospital was able to take proactive steps - such as use of bottled water and shower restrictions – until the potable water system could be sanitized with chlorine dioxide (reportedly one of the best, most cost-effective ways to sanitize water systems contaminated with Legionella). There were no reported incidents of Legionellosis associated with the Johns Hopkins event. These proactive steps reduced risk of lawsuits had the Legionella infestation gone undiscovered and patients been infected.1

Background:

Legionella is an ubiquitous, naturally-occurring bacterium (Legionella pneumophila) that is commonly found in surface waters and ponds. Colonies of Legionella can also populate various types of man-made water storage and conveyance systems such as cooling towers, building and hospital water supplies, fountains, hot tubs, humidification systems and refrigeration systems. The symptoms of Legionellosis are primarily respiratory in nature. The most common presentation of the disease is acute pneumonia.

Current (Reaction) Mode:

There are no qualitative symptomatic differences between Legionellosis and pneumonia – which can make diagnosis difficult. Legionellosis can only be confirmed using time-consuming laboratory methods such as lung tissue cultures or the demonstration of certain bacterial antigens in body fluids.2 The primary clinical "clue" to whether Legionella is the culprit for a given infection has historically been a cluster of two or more infected patients.

Action (Precaution) Mode:

Currently there are no uniform guidelines, rules or regulations regarding Legionella in the United States. Various state departments of heath have published guidelines for reporting confirmed cases to the CDC and performing potential source investigations. This "reaction mode" to addressing potential sources of Legionella infections has led to a "head-in-the-sand" mentality, especially given that remedial measures to address Legionella have historically been costly, and the potential of litigation would theoretically increase once knowledge of a Legionella contaminated building or hospital was obtained.

The CDC has a sample Legionella "Environmental Assessment of Water System" form available at its web site www.cdc.gov/legionella/files/environmentalassessmentinstrument.pdf. The CDC also refers hospital, hotels, hot tub maintenance staff and others to the ASHRAE Guideline 12-2000 for information on how to decontaminate Legionella-infected water systems. ASHRAE, as part of a discussion forum, proposed the following additional language in Section 4.2:3

4.2 Hazard Analysis and Control

Hazard analysis and control of Legionnaires' disease (LDB) associated with building water systems shall be conducted so as to provide answers to these fundamental questions for the facility:

  • What is the LDB hazard in this facility?
  • How is the hazard controlled at this facility?
  • How do we know that the hazard is being controlled in this facility?

The goal is to eliminate the LDB hazard in building water systems or reduce it to an extent that prevents harm to people. The Hazard Analysis Critical Control Point (HACCP) system has been proven successful for preventing environmental-source disease, is widely endorsed worldwide and shall be used to prevent Legionellosis associated with building water systems.

Hazard analysis and control implementation shall include seven elements (see Definition of Terms):

1. Hazard analysis;

2. Identification of critical control points;

3. Establishment of critical limits at critical control points;

4. Establishment of a monitoring plan for critical limits at critical control points;

5. Establishment of corrective actions for each critical limit;

6. Establishment of procedures to document all activities and results;

7. Establishment of procedures to confirm that a) the hazard had been eliminated or controlled under operating conditions (validation), b) the plan is being implemented properly (verification) and c) the plan is periodically reassessed.

Opportunity to Comment:

While it remains to be seen what the draft ASHRAE standard will actually look like, hospitals, hotels, cooling tower operators, and other potentially impacted stakeholders may want to comment on the draft ASHRAE standard. In any event, it is clear that the issue of Legionella is turning from a reactive to a preventive mode in the United States.

Footnotes

1 Some law firms are now specializing in representing Legionellosis-stricken plaintiffs.

2 While there is a relatively quick urinary antigen test for the most common type of Legionella strain – L. pneumophila serogroup 1 – the CDC recommends both a urinary antigen assay and culture of respiratory secretions in order to help identify to source of the infection.

3 The current ASHRAE Guideline 12-2000 does not contain any provisions regarding Legionella hazard analysis.

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