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Legionella bacteria, Legionnaire's disease testing & prevention InspectAPedia®  -     Legionella, mold, and other pathogenic risks in cooling systems & water When to inspect & test for Legionella bacteria

This chapter discusses Legionella bacteria, Legionnaire's disease testing & prevention advice for building inspectors and owners. This is a chapter of our full document describing the inspection, maintenance, and repair of residential air conditioning systems (A/C systems) to inform home buyers, owners, and home inspectors of common cooling system defects. [Photographs courtesy U.S. Department of Labor, OSHA - see references below.] © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

A Summary of Legionella sp. Health Concerns, Cooling Systems and Drinking Water

What are Legionella, Legionnaires' Disease, and Pontiac Fever?

Legionella, of which there are at least 40 species, include the species Legionella pneumophila which can cause infections in humans. The name was derived from the discovery of this bacterium as the cause of infection of a significant of number of attendees at a convention of the American Legion in Philadelphia in 1976. In that case the source of Legionella pneumophila was traced to the air conditioning system of the hotel where the convention was held.

Where do Legionella sp. bacteria occur?

Legionella sp. bacteria occur naturally in the environment and are likely to be found in potable water supplies, especially those coming from bodies of water such as lakes and reservoirs.

Legionella bacteria are not likely to be removed by normal potable water treatment systems. In turn, potable water from a municipal supply is the typical source of water used in cooling towers. Water from cooling towers or even aerosolized droplets of water from building plumbing fixtures (faucets and showers) or humidifiers or nebulizers may in turn spread Legionella bacteria to humans. Human infection by Legionella bacteria may take the form of Pontiac fever, or Legionellosis, which produces flu-like symptoms which can disappear after a few days.

More serious illness, Legionnaires' disease, is potentially fatal. Symptoms of Legionnaires' disease are typical of pneumonia in general and include high fever, dry cough, chills, and loss of appetite, headache, disorientation, and perhaps diarrhea or vomiting. In more advanced stages Legionnaires' disease can cause difficulty in breathing and chest pains. Legionnaires' disease is treated by antibiotics.

What is the Recommended Level for Legionella sp. Bacteria in Water?

The U.S. Environmental Protection Agency US EPA specifies a goal of zero microorganisms of Legionella sp. in potable water. (A MCLG or maximum contaminant level goal of zero). Legionella sp. bacteria can be removed from a water supply by heating methods including steam heating, ionization or possibly ozone treatment, UV light sterilization [which may not be reliable in all applications], use of strong disinfectant methods with chlorine, or copper-silver ionization treatment.

How and When Should We Inspect and Test for Legionella sp. Bacteria?

A component of the risk evaluation for any potential environmental concern in a building is the decision of how far to go in inspection and testing for hazardous materials, including evidence of Legionella sp. bacteria. The level risk determines the appropriate level of inspection and testing. In turn, the level of risk is comprised of several factors: the known history of the building, the visual observation of building conditions, and the vulnerability or health fragility of building occupants.

Factors increasing the health risk of Legionella sp. for individuals includes identifying the "at risk" population. These include: people who are heavy smokers or drinkers, people who have health conditions that weaken or threaten the immune system or pose special risk of respiratory illness (chronic obstructive pulmonary disease or COPD, kidney disease, or cancers of the head or neck), people who are undergoing chemotherapy or taking immunosuppressant drugs (cancer patients, organ transplant recipients), and people who are hospitalized and require special respiratory assistance measures (intubation, respiratory therapy, nebulizers).

More about risk assessment in buildings and the decision process for hiring a professional for more thorough inspection and testing (pertinent to mold investigations) is at When to hire a professional.

Legionellosis: Legionnaires' Disease (LD) and Pontiac Fever - Information from the U.S. CDC

What is Legionnaires' disease?

Legionellosis is an infection caused by the bacterium Legionella pneumophila. The disease has two distinct forms:

Legionnaires' disease, the more severe form of infection which includes pneumonia, and Pontiac fever, a milder illness.

Legionnaires' disease acquired its name in 1976 when an outbreak of pneumonia occurred among persons attending a convention of the American Legion in Philadelphia. Later, the bacterium causing the illness was named Legionella.

Legionnaires' disease (LEE-juh-nares) is caused by a type of bacteria called Legionella. The bacteria got its name in 1976, when many people who went to a Philadelphia convention of the American Legion suffered from an outbreak of this disease, a type of pneumonia (lung infection). Although this type of bacteria was around before1976, more illness from Legionnaires' disease is being detected now. This is because we are now looking for this disease whenever a patient has pneumonia.

Each year, between 8,000 and 18,000 people are hospitalized with Legionnaires' disease in the U.S. However, many infections are not diagnosed or reported, so this number may be higher. More illness is usually found in the summer and early fall, but it can happen any time of year.

What are the usual symptoms of legionellosis?

Legionnaires' disease can have symptoms like many other forms of pneumonia, so it can be hard to diagnose at first. Signs of the disease can include: a high fever, chills, and a cough. Some people may also suffer from muscle aches and headaches. Chest X-rays are needed to find the pneumonia caused by the bacteria, and other tests can be done on sputum (phlegm), as well as blood or urine to find evidence of the bacteria in the body.

These symptoms usually begin 2 to 14 days after being exposed to the bacteria.

A milder infection caused by the same type of Legionella bacteria is called Pontiac Fever. The symptoms of Pontiac Fever usually last for 2 to 5 days and may also include fever, headaches, and muscle aches; however, there is no pneumonia. Symptoms go away on their own without treatment and without causing further problems.

Pontiac Fever and Legionnaires' disease may also be called "Legionellosis" (LEE-juh-nuh-low-sis) separately or together.

How serious is Legionnaires' disease? What is the treatment for Legionnaires' disease?

Legionnaires' disease can be very serious and can cause death in up to 5% to 30% of cases. Most cases can be treated successfully with antibiotics [drugs that kill bacteria in the body], and healthy people usually recover from infection.

Where do Legionella bacteria come from?

The Legionella bacteria are found naturally in the environment, usually in water. The bacteria grow best in warm water, like the kind found in hot tubs, cooling towers, hot water tanks, large plumbing systems, or parts of the air-conditioning systems of large buildings. They do not seem to grow in car or window air-conditioners.

How do people get Legionnaires' disease?

People get Legionnaires' disease when they breathe in a mist or vapor (small droplets of water in the air) that has been contaminated with the bacteria. One example might be from breathing in the steam from a whirlpool spa that has not been properly cleaned and disinfected.

The bacteria are NOT spread from one person to another person.

Outbreaks are when two or more people become ill in the same place at about the same time, such as patients in hospitals. Hospital buildings have complex water systems, and many people in hospitals already have illnesses that increase their risk for Legionella infection.

Other outbreaks have been linked to aerosol sources in the community, or with cruise ships and hotels, with the most likely sources being whirlpool spas, cooling towers (air-conditioning units from large buildings), and water used for drinking and bathing.

Who gets Legionnaire's disease?

People most at risk of getting sick from the bacteria are older people (usually 65 years of age or older), as well as people who are smokers, or those who have a chronic lung disease (like emphysema).

People who have weak immune systems from diseases like cancer, diabetes, or kidney failure are also more likely to get sick from Legionella bacteria. People who take drugs to suppress (weaken) the immune system (like after a transplant operation or chemotherapy) are also at higher risk.

What should I do if I think I was exposed to Legionella bacteria?

Most people exposed to the bacteria do not become ill. If you have reason to believe you were exposed to the bacteria, talk to your doctor or local health department. Be sure to mention if you have traveled in the last two weeks.

A person diagnosed with Legionnaires' disease in the workplace is not a threat to others who share office space or other areas with him or her. However, if you believe that there your workplace was the source of the person's illness, contact your local health department.

Source Material Dated: October 12, 2005 Content source: Coordinating Center for Infectious Diseases / Division of Bacterial and Mycotic Diseases

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Legionellosis: Legionnaires' Disease, Air Conditioning Inspection Procedure and Photos - Technical Contributors/Reviewers

• Thanks to Mark Cramer, Tampa Florida, for assistance in technical review of the "Critical Defects" section and for the photograph of the deteriorating gray Owens Corning flex duct in a hot attic. Mr. Cramer is a Florida home inspector and home inspection educator.
• "Legionellosis: Legionnaires' Disease (LD) and Pontiac Fever", October 12, 2005 Content source: Coordinating Center for Infectious Diseases / Division of Bacterial and Mycotic Diseases U.S. Department of Health and Human Services, Centers for Disease Control US CDC, Division of Bacterial and Mycotic Diseases. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/legionellosis_g.htm
• "Legionella Infection Risk from Domestic Hot Water", Paola Borella et als., June 23, 2004, Abstract: "We investigated Legionella and Pseudomonas contamination of hot water in a cross-sectional multicentric survey in Italy. Chemical parameters (hardness, free chlorine, and trace elements) were determined. Legionella spp. We re detected in 33 (22.6%) and Pseudomonas spp. in 56 (38.4%) of 146 samples. Some factors associated with Legionella contamination were heater type, tank distance and capacity, water plant age, and mineral content. Pseudomonas presence was influenced by water source, hardness, free chlorine, and temperature. Legionella contamination was associated with a centralized heater, distance from the heater point >10 m, and a water plant >10 years old. Furthermore, zinc levels of <100 ™g/L and copper levels of >50 ™g/L appeared to be protective against Legionella colonization. Legionella species and serogroups were differently distributed according to heater type, water temperature, and free chlorine, suggesting that Legionella strains may have a different sensibility and resistance to environmental factors and different ecologic niches." CDC, http://www.cdc.gov/ncidod/eid/vol10no3/02-0707.htm
• OSHA Technical Manual re Legionnaire's disease - http://www.osha.gov/dts/osta/otm/otm_iii/otm_iii_7.html
• "What is Legionnaires' Disease?", U.S. Department of Labor, OSHA, publication at http://www.osha.gov/dts/osta/otm/legionnaires/pdf/sectioni.pdf - source of two images used in this article.
• US EPA Safe Drinking Water Hotline: 800-426-4791
• "Cooling Tower Legionella. Pneumophilia Study, CDC Joint Research Project. 1994. William K. McGrane, Ph.D. CH2M Hill. And. Lee Ditzler et als., www.zentox.com/CleanStreams/Legionella.pdf
• "Legionella in NY - How to Conduct a Legionella Risk Assessment", Mark Hodgson, LSC, Naperville IL & Diane Miskowski, MPH, EMSL Analytical, Inc., westmont NY, Crown Plaza, White Plains, 8 May 2007. Course description: "Guidelines for the control of Legionella in critical care hospitals in New York have been in place for two years. In October 2006, these guidelines were extended to include nursing homes and long term care facilities. Join us for this 8 hour seminar to learn all you need to know to conduct a Legionella health risk assessment, control it in your facility, and remediate it. This course will describe the ecology of the [Legionella] organism, the epidemiology of the disease [Legionnaire's disease], a discussion of some recent outbreaks, and the proper sampling methods and analysis of the bacteria. A significant amount of time will be spent discussing how to actually perform a Legionella risk assessment, and an overview of cooling towers and potable water system design and how that contributes to growth of the [Legionella] organism. Discussion will include where Legionella can be found in the engineered environment, and the use of biocides and other controls."
• Thanks to Craig Balchunas, AHI Accurate, LLC., a home inspection firm in Hyde Park, NY. - (800) 360-3998
• "Legionella", a public information poster provided free by LA Testing, an California environmental testing lab - www.LATesting.com.
• Thanks to Jon Bolton, an ASHI, FABI, and otherwise certified Florida home inspector who provided photos of failing Goodman gray flex duct in a hot attic.
• Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment ($69.00 U.S.).
• Thanks to Dave Burley, State of Vermont, for correspondence on this matter, 5/10/2007

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