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Legionella hazards and HVAC equipment:
This article describes 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. [
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.
he 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
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: email@example.com
"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.
"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.
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home",
U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
Allergies, Allergens, Allergy Testing in Buildings - References & Products
Allergen Tests in Buildings advice about how to test, what to look for, in evaluating the level of dog, cat, or other animal allergens in a building
"IgG Food Allergy Testing by ELISA/EIA, What do they really tell us?" Sheryl B. Miller, MT (ASCP), PhD, Clinical Laboratory Director, Bastyr University Natural Health Clinic - ELISA testing accuracy: Here is an example of Miller's critique of ELISA
http://www.betterhealthusa.com/public/282.cfm - Townsend Letter for Doctors and Patients
The critique included in that article raises compelling questions about IgG testing assays, which prompts our interest in actually screening for the presence of high levels of particles that could carry allergens - dog dander or cat dander in the case at hand.
http://www.tldp.com/issue/174/IgG%20Food%20Allergy.html contains similar criticism in another venue but interestingly by the same author, Sheryl Miller. Sheryl Miller, MT (ASCP), PhD, is an Immunologist and Associate Professor of Basic and Medical Sciences at Bastyr University in Bothell, Washington. She is also the Laboratory Director of the Bastyr Natural Health Clinic Laboratory.
Allergens: Testing for the level of exposure to animal allergens is discussed at http://www.animalhealthchannel.com/animalallergy/diagnosis.shtml (lab animal exposure study is interesting because it involves a higher exposure level in some cases
Allergens: WebMD discusses allergy tests for humans at webmd.com/allergies/allergy-tests
Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.
Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
Rodent control issues, including dander, fecal, and urine contamination of Buildings and Building insulation are discussed at our
Associations: Sick House, Sick Building, SBS - Air Quality, Government, Private Associations and Information Resources
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon) - The Atlas of Clinical Fungi is also available on CD ROM
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
"Disease Prevention in Home Vegetable Gardens,"
Department of Plant Microbiology and Pathology,
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous.
Rot concerns in buildings-some building mold such as Meruliporia incrassata "Poria" risks serious rot and hidden structural damage
US EPA: Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
OTHER IAQ ISSUES: How To Find and Address Other Indoor Air or Indoor Environment Contaminants Besides Mold
Mold or allergens may not be the only or even the main indoor environmental contaminant. Don't let media attention to mold
cause so much enviro-scare fear that other, possibly more urgent hazards go un-addressed.
Rodents, Mice, Squirrel Control - I find high levels of mouse and rodent dander, fecal dust, and urine-contaminated dust in some buildings,
and high levels of these materials in building insulation in those locations. If you have a mouse problem, particularly if mice and their waste (fecals or urine) are contaminating
the building HVAC or building insulation, may need both steps to clean up or remove infected materials and steps to stop an ongoing
rodent problem. If squirrels are a problem, the cleanup needs to include closing off entry openings into the building. Get some
help from a licensed pest control expert.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones