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Legionnaires' disease: detectable, curable, and preventable; Industry experts Robert F. Whitcomb and Edwin F. Goldstein reveal overlooked facility sources of deadly bacteria.

In 1977, it was discovered that Legionnaires' disease (LD), a respiratory illness, was caused by a new family of bacteria. Although we now know how to identify and treat it, many still needlessly die from LD--often in healthcare institutions, including nursing homes. To illustrate, a recent LD outbreak at a Philadelphia nursing home cost the lives offour residents before it was brought under control. (1) In the summer of 2003 there was a dramatic increase in reported cases all along the East Coast that has yet to be explained. (2) This disease can be prevented, if building operators, owners, and managers follow sufficient preventive maintenance procedures. They also should be aware that Legionnaires' disease can be detected and cured, with appropriate and timely procedures.


In 1976, attendees of an American Legion convention in Philadelphia were stricken with a pneumonia-like illness. The cause was traced to a newly discovered bacterium, which soon became known as Legionella pneumophila. (3) This family of bacteria has since been expanded. More than 15 known serogroups have been identified, including LD's less-threatening cousin, Pontiac fever. Fortunately, more sophisticated tests have been developed to diagnose and identify each (4) (figure 1).

Incidents of LD are now commonly reported to disease control centers and in the press, and it is one of the top three causes of community-acquired pneumonia. An estimated 25,000 or more cases occur each year in the United States, with more than 4,000 deaths attributed annually to Legionella pneumophila. It poses such a significant health risk that OSHA has devoted an entire chapter in its Technical Manual to recognizing, investigating, and controlling the disease. (5)

Untreated, LD can reach fatality rates as high as 40%, (6) yet treatments are quite effective if Legionella testing and diagnosis occur at an early stage, when pneumonia is first suspected. LD is most often fatal among adults with lowered immune deficiencies, such as the elderly and those who are hospitalized. Increasingly, cases are being reported in which normally healthy adults contract the disease and are not diagnosed properly until it is too late. (7) Therefore, it is especially important that staff who care for senior citizens or the sick are aware of the need to test for LD whenever pneumonia-like symptoms are evident.

Testing and Treatment Protocols

The initial screening for LD in patients can be done directly with a urine sample. Lab workers should be instructed to conduct urine antigen tests for Legionella. (8) If the antigen test comes back positive, then further tests of respiratory specimens are required to identify the exact strain of bacteria involved. These testing procedures are described in more detail by advisories published by health authorities, such as those distributed in July 2003 by the Philadelphia Department of Public Health. (9)


Once the disease is diagnosed as LD, several effective antibiotics are available for treatment, such as erythromycin (8) and fluoroquinolone. (9) This article's intention is not to prescribe medicine or treatment. Please refer to the advisories published by the referenced medical authorities and note that the research has proven that LD can be fully cured when treated in its early stages. Our assertion, and that of others in the water treatment industry, (10) is that LD fatalities can be prevented if healthcare professionals are aware of the need for early detection. This includes all personnel caring for those at high risk of contracting pulmonary diseases, such as immunosuppressed residents in nursing homes, rehabilitation centers, and life care facilities. (11)

Identify the Facility's Breeding Sites

LD is not contagious. It is contracted from the environment through inhalation of mists carrying Legionella bacteria. Several well-known sources for these mists include cooling towers, showerheads, fountains, and spas, as well as other less-obvious sources such as the misting machines found in produce sections of grocery stores. (12) The water temperatures in these potential sources allow very small quantities of Legionella bacteria to grow rapidly and concentrate. Legionella lives in the natural environment, travels through municipal water systems and, like so many bacteria, surrounds us every day. Inhaling high concentrations of Legionella bacteria easily can lead to infection. Failure to maintain these potential sources properly gives Legionella a place to propagate, usually in still, warm water, where exposure to air helps to carry a fine mist to unsuspecting victims.

The most publicized cases of LD were caused by mists emanating from cooling towers (13) (figure 2) that usually are located on building roofs or in out-of-the-way areas where only the building engineer goes to inspect their condition. Cooling towers are designed to circulate water through an air flow (to cool the water from the building's interior) and by their nature, mix warm water with passing air. If some of the warm water is not circulating, it easily can create stagnant breeding grounds for bacteria such as Legionella. When Legionella bacteria counts reach elevated levels (such as when the cooling tower is improperly treated or not cleaned often enough), the normal air flow around the building easily can become saturated with a vapor mist containing Legionella and an unsuspecting passerby can become infected. Under certain conditions, these contaminated mists can carry great distances, even infiltrating other nearby towers (figure 3).

Potable water systems and hot-water heaters have been shown statistically to be the more frequent source of LD. (13) In healthcare facilities, the disease often is spread via rarely used showerheads in bathrooms, water fountains, or other outlets where a fine mist can be created. If a shower in a nursing home goes unused for weeks or months, the warm-water residue left in the showerhead or plumbing can become a breeding ground for Legionella bacteria. Hot-water heating tanks (figure 4) are another breeding ground, although the danger is present only when bacteria-laden water mixes with air to form an aerosol mist.

Regular maintenance programs, such as superheating and flushing the hot-water tanks, superchlorinating domestic water systems, and bleaching the inside of showerheads, can prevent the contamination of potable water. Other advanced systemic methods available include ultraviolet sterilizers, ozonation systems, and copper-silver ionization units. (10)


Other sources can be found in some of the more upscale long-term care facilities--public spas and decorative fountains can be growth points, for example, as can hot tubs that are allowed to run for lengthy times without proper cleaning. Slow-circulating fountains where water is exposed to a heat source also could provide a place for Legionella bacteria to grow. Facility managers should identify any potential growth source and adopt appropriate maintenance procedures to it, with regular tests to detect Legionella bacteria.

The time and effort required go beyond protecting lives and health--another consideration is protecting the facility from potential lawsuits. In today's litigious environment, losing one patient to suspected LD could result in a costly legal settlement, unless it is shown that due diligence and good preventive maintenance practices are in place.

Protecting Healthcare Environments From LD

Nursing homes and senior care environments have the two most common sources of Legionella bacteria: cooling towers and domestic hot-water holding tanks. These are primary systems that need attention from building operating and maintenance personnel.



Because the water circulating in the cooling tower is segregated completely from other water systems, it can be treated with chemicals to prevent biologic buildup. (13)

To treat the cooling tower properly, a professional water-treatment service might be the best resource for supplying the proper chemicals and conducting regular maintenance tests. These professionals know how to test the recirculating water to ensure that the system is protected against corrosion, biologic buildup, and accumulating dirt, which is a constant threat to efficient cooling tower operation. Like elevator testing, this testing should be performed regularly, especially during warmer months of the year. Some states and localities already have established guidelines for hospitals, (14) and we believe that every building with immunosuppressed occupants should do likewise.

The other frequent source, the hot-water system, uses municipal or other potable water as a source, and is always subject to waterborne bacteria introduced from outside the facility. Therefore, each system requires different preventive maintenance procedures and each system should be tested regularly. A preventive maintenance program for domestic hot-water systems should be developed based upon the type offacility and residents. We recommend that maintenance managers be proactive and regularly test hot-water tanks and seldom-used showerheads.

The Testing Debate

It must be acknowledged that the question of the type of testing program needed has long been debated among industry experts. Although the Centers for Disease Control issues guidelines for the testing of various disease-causing bacteria, it has yet to issue guidance on Legionella testing. (8) OSHA requires thorough investigation of any outbreaks and continued monitoring of the suspected source. (5) Some state health authorities have adopted Legionella testing procedures for hospitals, including New York and Maryland. (15) The 2003 position paper by the Association of Water Technologies (AWT), (13) which represents regional water-treatment companies nationwide and has examined this issue in depth, reinforces the recommendation that building managers assess their facilities for the need of a program. In essence, the AWT suggests that facilities with higher-risk residents take a more proactive approach to Legionella detection and prevention.


Having been involved with the initial 1976 LD outbreak and after 40 years in the industry, we strongly recommend that all healthcare facilities adopt a proactive approach. For years, we've urged all facility managers to take the prudent steps to ensure their occupants are not exposed to Legionella bacteria from cooling towers or other potential breeding grounds. At the very minimum, cooling tower waters and domestic hot-water heaters of public buildings should be tested quarterly. In facilities housing sick or aged occupants, testing for Legionella pneumophila should be done even more frequently.

A proactive water treatment and Legionella testing program should be an integral part of every building's preventive management program. With such a program, and with the healthcare industry's increasing awareness and diligence towards detecting and treating outbreaks of LD, we should no longer have to read about tragic deaths caused by Legionella bacteria.


1. Sitton Stanley L. Pipe Suspected in Legionnaires' Illness. The Philadelphia Inquirer, July 10, 2002.

2. The Washington Times. Doctors Look for Legionnaires after Nationwide Surge, July 16, 2003.

3. Fraser DW, McDade JE. Legionellosis. Scientific American 1979:214;82-99.

4. Barbaree JM. Controlling Legionella in cooling towers. ASHRAE Journal 1991:6;38-42.

5. OSHA Technical Manual. Section III: Chapter 7 Legionnaires' Disease: II Disease Recognition. Washington, DC: Occupational Safety & Health Administration, January 1999.

6. Marston BJ, Lipman HB, Breiman RF. Surveillance for Legionnaires' disease: Risk factors for morbidity and mortality. Archives of Internal Medicine 1994:154;2417-22.

7. Agnvall E. Growing puzzle: Area officials investigate spike in Legionnaires' cases. The Washington Post, October 7, 2003.

8. Centers for Disease Control. Legionellosis: Legionnaires' disease (LD) and Pontiac Fever. Available online at

9. Philadelphia Department of Public Health. Increase in Legionella pneumonia, Philadelphia and surrounding regions, Philadelphia: Division of Disease Control Health Advisory, July 31, 2003.

10. Freije MR. Legionellae Control in health care facilities: A guide for minimising risks. HC Information Resources Inc., 1996.

11. Freije MR. Legionellae prevention training course: A comprehensive two-day seminar. Fairfax, Va.: Virginia Department of Mental Health, December 5-6, 2002.

12. Gilpin Testing Service, Division of Gilpin Limited. Legionnaires' disease: Facts & legal liability information. Available online at

13. Pearson WE, II. Legionella 2003: Update and AWT statement. McLean, Va.: Association of Water Technologies, June 2003.

14. Allegheny County Health Department. Approaches to prevention and control of Legionella infection in Allegheny County health care facilities. Pittsburgh: Allegheny County Health Department, January 1997, first revised edition.

15. State of Maryland Department of Health and Mental Hygiene. Report of the Maryland Scientific Working Group to Study Legionella in water systems in healthcare institutions. Baltimore: State of Maryland Department of Health and Mental Hygiene, June 14, 2000.

Robert F. Whitcomb is Vice-President and Edwin F. Goldstein is Chairman of Arc Testing Services of Maryland, Inc. For further information, phone (866) 360-0557 or e-mail

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Title Annotation:Focus on Infection Control
Author:Goldstein, Edwin F.
Publication:Nursing Homes
Geographic Code:1USA
Date:May 1, 2004
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