Industrial Water Engineering, Inc.

CHEMICAL WATER TREATMENT

toll free 1-800-543-6519

GSA # GS-10F-7884A (1/31/2007)

DOD Cage # 0MV90

 

 

OSHA TECHNICAL MANUAL

SECTION III: CHAPTER 7

LEGIONNAIRES' DISEASE

Contents:

I. Introduction

II. Disease Recognition

III. Source Identification

IV. Invetigative Protocol

V. Controls

Appendix III:7-1. Employee Awareness Program

Appendix III:7-2. Physical Survey and Water Sampling Protocol

Appendix III:7-3. Water Sampling Guidelines

Appendix III:7-4. Legionnaires' Disease Case Identification

Appendix III:7-5.

Water Treatment Protocols for Facilities That Have

Experienced a Legionnaires' Outbreak

I.INTRODUCTION.

This chapter provides information to assist industrial hygienists in the assessment

of work sites for potential Legionnaires' disease. It provides information on disease

recognition, investigation procedures to identify probable water sources, and

control strategies. The primary focus of this document is on the control and

prevention of contaminated water sources, not on case identification, an area of

expertise primarily exercised by local health departments frequently in conjunction

with the Centers for Disease Control and Prevention (CDC) in Atlanta. Appendices

include details on conducting an employee awareness program, water sampling

protocols and guidelines for acceptable levels of the organism in water, procedures

for identifying new cases of the disease, and water treatment and control

strategies for facilities where an outbreak has occurred.

II.DISEASE RECOGNITION.

A.CAUSATIVE AGENT.

1.Legionella pneumophila was first identified in 1977 by the CDC as the

cause of an outbreak of pneumonia that caused 34 deaths at a 1976

American Legion Convention in Philadelphia. L. pneumophila had

undoubtedly caused previous pneumonia outbreaks, but the organism's

slow growth and special growth requirements prevented earlier

discovery.

2.The diseases produced by Legionella are called legionellosis. More than

34 species of Legionella have been identified, and more than 20 linked

with human diseases. L. pneumophila causes the pneumonia known as

Legionnaires' disease and the flu-like Pontiac fever. L. pneumophila has

also been implicated in wound infections, pericarditis, and endocarditis

without the presence of pneumonia. Because the majority of

legionellosis is caused by L. pneumophila, this chapter will deal

exclusively with that organism. Cases where other species of Legionella

are involved in disease require actions similar to those to control

Legionnaires' disease.

3.The L. pneumophila bacteria are gram-negative rods that exist in a

number of distinguishable serogroups. Each serogroup contains further

subtypes that have different surface structures on the cell membrane

and can be distinguished by special tests. Evidence indicates that some

Legionella serogroups are more virulent than others. L. pneumophila

serogroup 1 is the most frequently identified form of the bacterium

isolated from patients with Legionnaires' disease, although other

serogroups and subtypes of the bacterium are frequently isolated from

water sources. Serogroups 4 and 6 are the next most frequently linked

with disease.

B.SYMPTOMS.

1.Legionnaires' disease has an incubation period of two to ten days.

Severity ranges from a mild cough and low fever to rapidly progressive

pneumonia and coma. Early symptoms include malaise, muscle aches,

and slight headache. Later symptoms include high fever (up to 105°F),

a dry cough, and shortness of breath. Gastrointestinal symptoms

including vomiting, diarrhea, nausea, and abdominal pain are common.

The disease is treated with erythromycin or a combination of

erythromycin and rifampin.

2.Pontiac fever is a non-pneumonia, flu-like disease associated with, and

likely caused by, the Legionella bacterium. This disease has an "attack

rate" of 90% or higher among those exposed, and a short incubation

period, 1-3 days. Complete recovery usually occurs in 2-5 days without

medical intervention. The factors that cause the same organism to

produce two illnesses with major differences in attack rate and severity

are not known.

C.INCIDENCE. In the U.S., Legionnaire's disease is considered to be fairly

common and serious, and the Legionella organism is one of the top three

causes of sporadic, community-acquired pneumonia. Because it is difficult to

distinguish this disease from other forms of pneumonia, many cases go

unreported. Approximately 1,000 cases are reported annually to the CDC, but

it is estimated that over 25,000 cases of the illness occur each year and

cause more than 4,000 deaths.

D.RISK FACTORS. Legionnaires' disease is frequently characterized as an

"opportunistic" disease that most frequently attacks individuals who have an

underlying illness or weakened immune system. The most susceptible include

persons who are elderly, smokers, and immunosuppressed. Individuals with

chronic obstructive pulmonary disease (COPD), organ transplant patients, and

persons taking corticosteroid therapy are also at elevated risk. The attack

rate for the average population is approximately 5% or less. The fatality rate

is similar to that of other forms of pneumonia, approximately 15%.

E.DIAGNOSIS. CDC guidelines define two types of cases of Legionelloses,

probable and confirmed. A probable case of Legionnaire's disease is a person

who experienced an illness clinically compatible with Legionnaire's and has a

single antibody titer of 256 or higher (discussed below), and can be

associated with a population of individuals who have experienced confirmed

cases of the disease (outbreak). A confirmed case of Legionella requires a

physician's diagnosis of pneumonia based on a chest x-ray and positive

laboratory test results. A laboratory test is necessary for confirmation

because the symptoms and x-ray evidence of Legionnaires' disease resemble

those of other types of pneumonia. Various methods are used to confirm the

presence of the disease.

1.Culture of the Organism. The definitive laboratory method of confirming

the presence of the disease is by culturing viable cells of Legionella

from sputum, bronchial washing, or autopsy on special media. Further

identification of the cultured cells will identify the species and

serogroup. Special tests may determine subtype of certain isolates. The

sensitivity of this test to detect the disease is reported to be about

70%.

2.Urine Antigen Test. The detection of antigen from L. pneumophila in the

urine is considered a reliable measure of the disease. These antigenic

materials may include L. pneumophila cells or portions of cells in the

urine during and after the disease. The presence of antigen in the urine

is a strong indicator of the disease, and a patient may have a positive

response for several months following the disease. The sensitivity of

this test is limited because the only commercially available urinary

antigen test detects only serogroup 1 forms of L. pneumophila. The

CDC recommends only the radioimmunoassay (RIA) test because the

latex antigen (LA) test has a high false-positive rate. Fortunately,

80-90% of the clinically diagnosed cases are caused by serogroup 1.

The absence of a positive urinary test is not proof that a patient did

not have Legionnaires' disease, but merely indicates the absence of

antigen in the urine at the time of the test.

3.Direct Fluorescent Antibody (DFA) Staining. Direct fluorescent antibody

staining of lung aspirates can detect L. pneumophila. However, this

test is frequently negative during the initial stages of the disease

because few organisms are present in the aspirate or sputum. This test

also requires an antigen-specific reagent. There are a multitude of

serogroups and subtypes of L. pneumophila, and a test will be negative

if the exact antigen-specific reagent is not included.

4.Serology (Antibody Titers).

a. An increase in the antibody level in the serum of infected persons

occurs several weeks after the onset of the disease. A fourfold

increase in the antibody titer coupled with a physician's diagnosis of

pneumonia is considered a reliable indicator of disease. This is measured

by comparing the antibody level four to eight weeks after onset

(convalescent titer) to an initial (acute) titer at the beginning of the

disease. Pontiac fever also produces an elevated antibody titer, but the

flu-like symptoms of this disease do not match those of Legionnaires'

disease.

b. Frequently only a convalescent titer has been measured from

individuals who had symptoms of the disease. For situations in which

these cases are associated with an outbreak of Legionnaires' disease, a

single titer of 256 to 1 or higher is generally used as a presumptive

indication of disease (probable case). Antibody strength is determined

by the number of dilutions of serum which elicit a positive antibody

response. The reciprocal value of the number of dilutions is the

antibody titer. For example, an antibody titer of 256 means a positive

antibody test of the patients's serum following serial dilutions of 1:2,

then 1:4, then 1:16, etc., until the 1:256 dilution point is reached.

c. The indirect fluorescent antibody (IFA) test is the accepted

diagnostic tool for demonstrating L. pneumophilia exposure. Another

widely used test of antibody response is the enzyme-linked

immunosorbent assay method (ELISA). CDC believes that direct

comparison of results between IFA and ELISA is not reliable because

there are insufficient data to compare the two. The ELISA method has

gained wide medical acceptance as a useful means of demonstrating

exposure to Legionella.

F.TRANSMISSION.

1.The likelihood of contracting Legionnaires' disease is related to the level

of contamination in the water source, the susceptibility of the person

exposed, and the intensity of exposure to the contaminated water.

Disease transmission usually occurs via inhalation of an aerosol of water

contaminated with the organism. Aspiration of contaminated water into

the lungs may also cause the disease. In the Philadelphia Legionnaires'

disease outbreak, the hotel's cooling tower was identified as the likely

source of the disease, although domestic water sources were not

evaluated.

2.The disease has been associated with domestic hot-water systems in a

number of outbreaks. In many instances it has been difficult to identify

a likely source for aerosolization of the suspected water source.

Although transmission of the disease other than through direct

inhalation of aerosols may occur, the mechanisms are not clearly

understood. The organism requires water, and the disease cannot occur

in the absence of a contaminated water source. There is no evidence

that the disease can be transmitted from one person to another.

III.SOURCE IDENTIFICATION.

A.CONDITIONS THAT PROMOTE GROWTH.

1.L. pneumophila bacteria are widely distributed in water systems. They

tend to grow in biofilms or slime on the surfaces of lakes, rivers and

streams, and they are not eradicated by the chlorination used to purify

domestic water systems. Low and even nondetectable levels of the

organism can colonize a water source and grow to high concentrations

under the right conditions.

Conditions that promote growth of the organism include heat, sediment,

scale, and supporting (commensal) microflora in water. Common water

organisms including algae, amoebae, and other bacteria appear to

amplify Legionella growth by providing nutrients or harboring the

organism. Because of its ability to remain viable in domestic water

systems, it is capable of rapid multiplication under the proper

conditions.

2.Water conditions that tend to promote the growth of Legionella include:

stagnation;

temperatures between 20° and 50°C (68° - 122°F) (The optimal

growth range is 35° - 46°C [95° - 115°F]);

pH between 5.0 and 8.5;

sediment that tends to promote growth of commensal microflora;

and

micro-organisms including algae, flavobacteria, and Pseudomonas,

which supply essential nutrients for growth of Legionella or harbor

the organism (amoebae, protozoa).

B.COMMON SOURCES OF CONTAMINATED WATER.

1.Water sources that frequently provide optimal conditions for growth of

the organisms include:

cooling towers, evaporative condensers, and fluid coolers that

use evaporation to reject heat. These include many industrial

processes that use water to remove excess heat;

domestic hot-water systems with water heaters that operate

below 60°C (140°F) and deliver water to taps below 50°C

(122°F);

humidifiers and decorative fountains that create a water spray

and use water at temperatures favorable to growth;

spas and whirlpools;

dental water lines, which are frequently maintained at

temperature above 20°C (68°F) and sometimes as warm as 37°C

(98.6°F) for patient comfort; and

other sources including stagnant water in fire sprinkler systems

and warm water for eye washes and safety showers.

2.Water stored below 20°C (68°F) is generally not a source for amplified

L. pneumophila levels. However, high levels of bacteria have been

measured in the water supplying ice machines. The source of

amplification in this case was thought to be heat from the condenser

coil of the ice maker to the cold water supply. However, no cases of

Legionnaires' disease have been linked to consumption of ice made from

contaminated water.

C.MONITORING.

1.Air. An air sample applied to special culture plates by an Andersen-type

sampler sometimes demonstrates the presence of the organism in the

air. However, negative results are frequent because of the difficulty in

maintaining viability of the organism on the culture plates. Air sampling

for Legionella is strongly not recommended as a means of measuring

potential exposure because of the high likelihood of false negatives.

2.Water. Analysis of water samples from a source suspected of being

contaminated with L. pneumophila is a valuable means of identifying

potential sources of the disease. A qualified microbiological laboratory

experienced in Legionella detection can determine the number of

organisms present in colony forming units (CFU) per volume of water

and can identify the different serogroups of Legionella pneumophila in

the sample. Appendix III:7-2 provides details on the collection, storage,

and shipping of water samples.

D.MICROBIOLOGICAL ANALYSIS OF WATER SAMPLES.

1.Cultured Samples. Water samples are cultured on special buffered

charcoal yeast extract (BCYE) culture media. Selective isolation

processes to eliminate other microbial overgrowth can determine the

number of CFU of L. pneumophila per milliliter of water. This process of

growth and isolation is time-consuming, and results typically require

7-14 days from the time of submission.

Cultured samples can also be analyzed to identify specific serogroups.

Matching the same serogroup and subtype of organism in the patient as

found in a water source is considered strong evidence of an associated

link.

2.Direct Fluorescence Antibody (DFA). The number of organisms in a

water sample can also be determined via direct fluorescence antibody

(DFA) conjugate tests that stain the organism with a fluorescent dye.

This test is unable to distinguish between live and dead bacteria and

may also have some cross-reactivity with other bacteria. Sample

results can be available in one or two days, and this method can be

useful in screening water samples. Use caution, however, in interpreting

the results since the potential exists for both false positive and

negative results.

3.DNA Amplification. A relatively new method for rapid, specific detection

of the organism in water employs a polymerase chain reaction (PCR)

process to amplify and then detect portions of DNA unique to L.

pneumophila. This method can produce results in 1 day, and preliminary

evidence indicates that its sensitivity and specificity are comparable to

those of cell culture, which can take 10-14 days to obtain results.

Further testing may lead to acceptance of this technique as the

method of choice for monitoring water sources for contamination.

E.INTERPRETATION OF SAMPLE RESULTS.

1.The probability of infection with L. pneumophila is a function both of

the intensity of the exposure dose and the level of host susceptibility.

Because total eradication of Legionella may not be possible, an

acceptable control strategy is to minimize the number of organisms

present in a water source. Ample evidence indicates that Legionella

levels are readily controllable. A survey of over 1,000 cooling towers

indicates that approximately 60% contained nondetectable levels of L.

pneumophila when measured by DFA analysis for the number of

organisms per milliliter of water (detection limit is 10 bacteria per

milliliter of water). In another survey of 663 cooling towers, 57%

contained Legionella that were not detected when measured by culture

(detection limit less than 1 CFU/mL). Other studies of domestic

hot-water sources indicate that although the organism is common,

especially in large hot-water systems, practical control measures can

limit the potential for amplification.

2.A private consulting firm and microbiological laboratory, PathCon Inc. of

Norcross, Georgia, has introduced suggested guidelines for control of

the organism based on the number of CFU of L. pneumophila per

milliliter of water (Appendix III:7-3). These guidelines vary depending on

the water source, a recognition by the authors that dose is related

both to the potential for exposure and to concentration. For example,

recommended exposure limits for contaminated water from a humidifier,

which would involve direct exposure to an aerosol are lower than for a

cooling tower where the opportunity for exposure is normally less. Work

operations such as maintenance on cooling towers may involve direct

exposure to cooling tower mist, and precautions to minimize exposure

are always necessary. The authors recognize that these guidelines are

based on limited data, but they represent the best available information

and must suffice until the dose effect of L. pneumophila is better

understood.

IV.INVESTIGATION PROTOCOL.

A.COMMUNITY HEALTH CONCERNS. It is important to remember that an

outbreak of Legionnaires' disease among workers may have its origin in the

community and may not be related to the work environment. A Legionnaires'

outbreak is both an occupational and a public-health concern, and the

investigation may include local public health departments and the Centers for

Disease Control (CDC). To minimize employee risk and maximize the

effectiveness of effort, close coordination among OSHA, other public

agencies, and the employer is imperative.

B.TYPES OF INVESTIGATIONS.

1.The course of action chosen during an investigation of a facility should

be based on the degree of certainty that the site is the source of a

reported illness. For this reason, two investigation protocols are based

on differing levels of suspected risk for exposure to Legionella. It is

important to remember that these procedures are provided only to

assist in the investigation of potential Legionnaires' cases. Individual

circumstances may require changes in the investigation. All cases

require sound professional judgment in deciding the appropriate course

of action.

2.A level-one investigation may be initiated when there is a probable

basis for suspecting that workplace water sources are contaminated

with Legionella, or when there is information that one case of

Legionnaires' disease may exist. A level-two investigation should be

conducted when more then one possible case of Legionnaires' disease

has been reported at a facility.

3.If two or more cases of the disease can be attributed to a work site,

assume that a Legionnaires' disease outbreak has occurred. If evidence

indicates that the outbreak is still in progress (that is, at least one of

the cases has occurred in the last 30 days), prompt actions should be

undertaken to provide maximum protection to employees and eliminate

the hazard. Appendix III:7-5 includes examples of actions required to

control water sources where an outbreak has occurred.

4.Both investigations follow the same general pattern and include a

preliminary opening conference, a walk-through of the facility to

conduct a physical assessment of the water systems, a more detailed

examination of the systems including a review of maintenance records,

assessment of findings, and a closing conference to present control

actions based on the findings.

C.LEVEL-ONE INVESTIGATION. Use the following procedure when Legionnaires'

disease may be related to the work environment.

1.Step 1. Obtain an overview of all water systems at the facility.

a. A facilities engineer or experienced member of the building

maintenance staff should be available to explain system operation and

assist in the walkthrough investigation. This person should have a

working knowledge of the system's design and current operation.

b. The overview of the water systems should include plumbing

systems, heating-ventilating-air-conditioning (HVAC) systems, and

other water reservoirs. A review of the plumbing system should include

both hot and cold domestic water systems, water heaters, distribution

pipes, water coolers, water treatment equipment, connections to

process water systems protected (or unprotected) by backflow

preventers, and storage tanks.

c. The HVAC system review should include cooling towers, evaporative

condensers, fluid coolers, humidifiers, direct evaporative air-cooling

equipment, indirect evaporative air-cooling equipment, air washers for

filtration, etc. Note the location of the fresh-air intakes of the building's

air-handling units relative to water sources such as the cooling towers.

d. Investigate other potential sources of employee exposure including

decorative fountains, plant misters, whirlpools, spas, tepid-water

eye-washes and safety showers, humidifiers, and water for cooling

industrial processes.

e. Review maintenance records on water systems including water

heaters and cooling towers. The records should include temperature

checks of domestic water, visual and physical checks of cooling towers,

and reports of cooling-tower water-quality assessment and chemical

treatment.

f. Identify the locations of portions of the system in which water is

allowed to stagnate such as storage tanks or unused plumbing pipe

sections ("dead legs"), or infrequently used faucets. Check for

cross-connections between domestic and process water systems, and

note the condition and type of back-flow prevention devices.

g. Investigate recent major maintenance or changes in the system's

operation. Determined if there were recent or frequent losses of water

pressure from the incoming water supply due to line breakage or street

repairs. The failure of a back-flow prevention device under loss of

pressure can contaminate the system.

2.Step 2. Conduct a walk-through investigation of the facility.

a. Equipment you will need includes a thermometer for measuring water

temperatures, a flashlight, and a film or video camera to record

observations. Measure and record the temperature of water drawn from

each storage-type water heater in the facility. This temperature may

be significantly below the water heater's gauge temperature because of

heat stratification. Note the presence of rust and scale in this water.

b. Record the maximum temperature of water at faucets connected to

each water heater on the system. Record temperatures at locations

near, intermediate, and distant from the heaters. It may be necessary

to run the water for several minutes before it reaches a temperature

maximum.

c. Examine the water temperature and the potential for stagnation of

cold-water storage tanks used for reserve capacity or to maintain

hydrostatic pressure. These should be protected from temperature

extremes and covered to prevent contamination. Record the

temperature of the domestic cold-water lines at various locations within

the facility. Note both the initial temperature and the final equilibrium

temperature on the cold-water line, and record the time required to

reach equilibrium, because this can be an indicator of the amount of

stagnation in the system.

d. Evaluate cooling towers, evaporative condensers, and fluid coolers

for biofilm growth, scale buildup, and turbidity. Record the location of

the tower relative to fresh-air intakes, kitchen exhausts, leaves, plant

material, or other sources of organic material that might contribute to

the growth of the organism.

e. Record the general condition of the cooling tower. Determine the

presence and condition of drift eliminators, which are designed to limit

the vapor release from the units, along with the basin temperature of

the water in the cooling tower if it is currently being operated. If the

cooling tower is operating and is suspected of being contaminated,

wear appropriate respiratory protection in the form of a half-face piece

respirator equipped with a HEPA or similar type of filter capable of

effectively collecting one-micron particles during the examination of the

system.

f. Note the location and evaluate the condition of the sumps for the

cooling tower(s), evaporative condenser(s), and fluid cooler(s). These

sumps are sometimes located indoors to protect them from freezing.

Record the locations of any cross-connections between the cooling

tower water system and any domestic water system. These may supply

a back-up source of cool water to refrigeration condenser units or

serve to supply auxiliary cooling units. The lack of a regular

maintenance schedule or water-treatment program for a cooling tower

or evaporative condenser system strongly suggests a potential for

Legionella contamination.

3.Step 3. Assess the results of the walkthrough investigation to

determine the course of action. If no potential problems are identified,

the operating temperatures measured at water heaters are 60°C

(140°F) or above, and the delivery temperature at distant faucets is

50°C (122°F) or higher, no further action will be necessary. However, if

the system is poorly maintained and operating temperatures are below

recommended minimums, then recommendations for corrective action

should be made.

4.Step 4. Recommend control actions.

a. Details of suggested control actions are discussed in Section E.

These actions may include disinfection of the domestic water system

via heat treatment, chlorination, or other means, and cleaning and

disinfecting the cooling tower system according to the Wisconsin

Division of Health protocol for "Control of Legionella in Cooling Towers"

or a similar process for cleaning heat rejection systems that follows

sound practices to minimize potential for Legionella growth.

b. Additional actions may include eliminating dead legs in the plumbing

system, insulating plumbing lines and installing heat tracing to maintain

proper temperatures in the system, eliminating rubber gaskets, and

removing or frequently cleaning fixtures such as aerators and shower

heads.

c. Corrective actions limited to raising the water heater temperature

without evaluating the system for points of stagnation, heat loss and

gain, cross-contamination, and other factors that contribute to growth

are generally not sufficient.

d. For a level-one investigation it is not recommended that water

samples be collected to confirm the presence of Legionella in the

system. The absence of proper operating conditions alone is sufficient

for assuming that the water system can pose an unnecessary risk to

the employees. Take water samples after the completion of the control

actions to confirm that the corrective measures were successful. The

employer may also want to obtain samples before starting corrective

actions to assess the extent of the problem.

e. The employer should take necessary corrective actions even if the

results of presampling are negative. Water sampling can produce false

negatives, a contaminated portion of the system may have been

missed, and the absence of Legionella organisms at the time of sampling

does not insure that the system will remain negative.

f. If, after control actions, the Legionella levels in a water source

exceed the guidelines in Appendix III:7-3, re-examine the water system

to determine if potential contamination points within the system were

overlooked and reassess control procedures to determine if they were

performed properly. Repeat the procedures as needed until

contamination levels meet the guidelines.

D.LEVEL-TWO INVESTIGATION. A level-two investigation is similar to a

level-one investigation with several additional steps. Supplemental actions

include: (1) medical surveillance of all employees currently on sick leave to

identify any new cases, (2) employee awareness training on the disease to

minimize employee concerns and aid in early recognition of new cases, (3)

assessment of past sick-leave absences for undetected cases of the disease,

and (4) collection of water samples during the walkthrough assessment.

1.Step 1. Assess water systems as described for a level-one

investigation.

2.Step 2. Conduct a second walkthrough survey of the facility and

collect water samples. Estimate the size of the building and the number

of water services during the initial walkthrough and prearrange supply

and shipping of the required number of sterile sample containers with

the appropriate laboratory. (See Appendix III:7-2 for water sampling

procedures.)

3.Step 3. Initiate an employee awareness program and monitor current

sick leave for new cases. It is important to ensure that employees

understand the early symptoms of the disease and seek medical

assistance promptly. It is imperative not to alarm the workers. It is

equally important to stress the importance of the need to know the

health status of all employees on sick leave. (See Appendix III:7-1,

Employee Awareness Program.)

4.Step 4. Review worker absences to detect other cases. This requires

identification of all employees who took three or more consecutive days

of sick leave from approximately six weeks before the case of

Legionnaires' disease was identified up to the present. Request those

employees who may have had pneumonia during this period to undergo

additional voluntary tests for evidence of Legionnaires' disease. (See

Appendix III:7-4, Case Identification.)

5.Step 5. Assess results of worker absence survey and analysis of water

systems. If evidence indicates more than one case of Legionnaires'

disease at the workplace, then the site should be treated as having an

outbreak. Take immediate control of all water sources to eliminate

potential for exposure, and take measures to eliminate the hazard. (See

Appendix III:7-5.)

No action is necessary if the results of the investigation are negative,

that is, (1) all water and HVAC systems are well maintained and in good

operating condition; (2) all water sample results are negative or

acceptably low (Appendix III:7-3); and (3) no new cases of the disease

have been identified at the work site. Under these circumstances,

assume that the site is not the origin of the identified case.

6.Step 6. For recommended control actions, see the level-one

investigation.

7.Ongoing Outbreak.

a. If the evidence indicates that two or more cases of Legionnaires'

disease have occurred at a site, and at least one of the cases was

within the last 30 days, assume that an outbreak is in progress and

requires a high-priority investigation and prompt action. Conduct a

level-two investigation as outlined above, and take the following

precautions to protect building occupants.

b. Immediately initiate control measures to prevent additional

exposures to all water systems that have a reasonable potential for

worker exposure including hot and cold domestic water, cooling towers,

humidifiers, and any other potential sources of water exposure. Collect

appropriate water samples to determine Legionella levels before

shutting down the water systems (Appendix III:7-2). These sample

results will be invaluable in establishing the cause of the outbreak. A

member of the building maintenance or engineering staff who has a

working knowledge of the system's design and current operation can

explain how the water system operates and the proper procedure for a

controlled shutdown.

These control actions need not require facility shutdown. Temporary

provisions can allow work to continue: bottled water can be supplied

for drinking, shutting off water heaters can eliminate hot-water access,

and temporary cooling towers can allow work to continue.

V.CONTROLS.

A.GENERAL DISCUSSION. This section contains background information on water

system operations and proper controls to prevent Legionella amplification.

This discussion encompasses a variety of water systems, some of which have

not been implicated with outbreaks of Legionnaires' disease. Nevertheless, it

is important to remember that any water system can be a source of disease if

the water in it is subjected to conditions that promote growth of the

organism. Remember, however, that the primary sources of exposure to

contaminated water are heat rejection systems (cooling towers, fluid coolers,

etc.) and domestic hot-water systems.

B.COOLING TOWERS, EVAPORATIVE CONDENSERS, AND FLUID COOLERS. The

function of cooling towers, evaporative condensers, and fluid coolers is to

reject heat from system fluids through evaporation. Cooling towers remove

heat from condenser water via direct-contact evaporation in a wet airstream.

This cooled water circulates through the condenser side of a mechanical

refrigeration unit to absorb heat. Evaporative condensers operate similarly,

except that the refrigerant condenser coils are directly inside the wet air

stream and water passing over the coils directly cools the refrigerant. Fluid

coolers are employed to reject heat from industrial processes, computer-room

air conditioners, etc. Like evaporative condensers, fluid coolers have

heat-exchanger coils directly in the wet air stream.

Because all of these systems use a fan to move air through a recirculated

water system, a considerable amount of water vapor is introduced into the

surroundings despite the presence of drift eliminators designed to limit vapor

release. In addition, this water may be in the ideal temperature range for

Legionella growth, 20° - 50°C, 68° - 122°F.

1.Inspection and Maintenance. Visual inspection and periodic

maintenance of the system are the best ways to control growth of

Legionella and related organisms. Good maintenance is necessary both

to control Legionella growth and for effective operation. The system

should be properly monitored and maintained to prevent buildup of scale

and sediment and bio-fouling, all of which support Legionella growth and

reduce operating efficiency.

2.Biocide. Unfortunately, measurements of water quality such as total

bacterial counts, total dissolved solids, and pH have not proven to be

good indicators of Legionella levels in cooling towers. Periodic use of

biocides is needed to ensure control of Legionella growth.

a. Little information exists on the demonstrated effectiveness of many

commercial biocides for preventing Legionella growth in actual

operations. Recent Australian studies indicate that Fentichlor

[2,2'-thiobis (4-chlorophenol)] used weekly for 4 hours at 200 ppm, or

bromo-chloro-dimethyl-hydantoin (BCD) in a slow-release cartridge at

an initial concentration of 300 ppm are effective in controlling the

growth of Legionella. There are no U.S. suppliers of Fentichlor, although

the chemical is liscensed by the EPA for water treatment in cooling

towers. Towerbrom 60MTM, a chlorotriazine and sodium bromide salt

mixture, has been reported to be effective when alternated with BCD

for control of Legionella in U.S. studies of Legionella contamination of

cooling towers. The Australian study also indicates that quaternary

ammonium compounds, widely used for control of bio-fouling in cooling

towers, are not effective in controlling Legionella.

b. Traditional oxidizing agents such as chlorine and bromine have been

proven effective in controlling Legionella in cooling towers. Continuous

chlorination at low free residual levels can be effective in controlling

Legionella growth. It is important, however, that the proper oxidant

level be established and maintained because free residual chlorine

above 1 ppm may be corrosive to metals in the system and may

damage wood used in cooling towers; free residual levels below 1 ppm

may not adequately control Legionella growth. Chlorine also combines

with organic substances in water to form toxic by-products that are of

environmental concern. Frequent monitoring and control of pH is

essential for maintaining adequate levels of free residual chlorine. Above

a pH of 8.0, chlorine effectiveness is greatly reduced. Proper control of

pH will maintain the effectiveness of chlorination and minimize corrosion.

c. Bromine is an effective oxidizing biocide. It is frequently added as a

bromide salt and generated by reaction with chlorine. Bromine's

effectiveness is less dependent than chlorine on the pH of the water; it

is less corrosive; and it also produces less toxic environmental

by-products.

d. The effectiveness of any water-treatment regimen depends on the

use of clean water. High concentrations of organic matter and dissolved

solids in the water will reduce the effectiveness of any biocidal agent.

Each sump should be equipped with a "bleed," and make-up water

should be supplied to reduce the concentration of dissolved solids.

3.Design.

a. One of the most effective means of controlling the growth of

Legionella is to maintain sump water at a low temperature. Sump-water

temperatures depend on tower design, heat load, flow rate, and

ambient dry-bulb and wet-bulb temperatures. Under ideal conditions,

sump-water temperatures in evaporative devices approach the ambient

wet-bulb temperature, and that may be low enough to limit Legionella

amplification. System design should recognize the value of operating

with low sump-water temperatures.

b. High-efficiency drift eliminators are essential for all cooling towers.

Older systems can usually be retrofitted with high-efficiency models. A

well-designed and well-fitted drift eliminator can greatly reduce water

loss and potential for exposure. Other important design features include

easy access or easily disassembled components to allow cleaning of

internal components including the packing (fill). Enclosure of the system

will prevent unnecessary drift of water vapor, and other design features

to minimize the spray generated by these systems are also desirable.

4.Frequency of Cleaning. Cooling towers should be cleaned and

disinfected at least twice a year. Normally this maintenance will be

performed before initial start-up at the beginning of the cooling season

and after shut-down in the fall. Systems with heavy bio-fouling or high

levels of Legionella may require additional cleaning. Any system that

has been out of service for an extended period should be cleaned and

disinfected. New systems require cleaning and disinfecting because

construction material residue can contribute to Legionella growth.

5.Wisconsin Protocol. Acceptable cleaning procedures include those

described in the Wisconsin Protocol. This procedure calls for an initial

shock treatment with 50 ppm free residual (total) chlorine, addition of

detergent to disperse bio-fouling, maintenance of 10 ppm chlorine for

24 hours, and a repeat of the cycle until there is no visual evidence of

biofilms. To prevent exposure during cleaning and maintenance, wear

proper personal protective equipment: a Tyvek-type suit with a hood,

protective gloves, and a properly fitted respirator with a high-efficiency

particulate (HEPA) filter or a filter effective at removing one-micron

particles.

6.Recordkeeping. A description of the operating system (which includes

all components cooled by the system) and details of the make-up water

to the system should be available. Written procedures for proper

operation and maintenance of the system should indicate the use of

scale and corrosion inhibitors, antifoaming agents, and biocides or

chlorine use and should be readily available. Log books should list dates

of inspections and cleanings, water-quality test results, and

maintenance.

C.DOMESTIC HOT-WATER SYSTEMS.

1.Background. Domestic hot-water systems are frequently linked to

Legionnaires' outbreaks. The term "domestic" applies to all nonprocess

water used for lavatories, showers, drinking fountains, etc., in

commercial, residential, and industrial settings. Disease transmission

from domestic hot water may be by inhalation or aspiration of

Legionella-contaminated aerosolized water. Water heaters that are

maintained below 60°C (140°F) and contain scale and sediment tend to

harbor the bacteria and provide essential nutrients for commensal

micro-organisms that foster growth of L. pneumophila. Large water

heaters like those used in hospitals or industrial settings frequently

contain cool zones near the base where cold water enters and scale

and sediment accumulate. The temperature and sediment in these

zones can provide ideal conditions for amplification of the organism.

Dead legs (i.e., sections of piping or plumbing that have been altered or

capped such that water cannot flow through) and nonrecirculated

plumbing lines that allow hot water to stagnate also provide areas for

growth of the organism.

2.Design. Water systems designed to recirculate water and minimize dead

legs will reduce stagnation. If potential for scalding exists, appropriate,

fail-safe scald-protection equipment should be employed. For example,

pressure-independent, thermostatic mixing valves at delivery points can

reduce delivery temperatures. Point-of-use water heaters can eliminate

stagnation of hot water in infrequently used lines. Proper insulation of

hot-water lines and heat tracing of specific lines can help maintain

distribution and delivery temperatures.

3.Maintenance.

a. To minimize the growth of Legionella in the system, domestic hot

water should be stored at a minimum of 60°C (140°F) and delivered at

a minimum of 50°C (122°F) to all outlets. The hot-water tank should be

drained periodically to remove scale and sediment and cleaned with

chlorine solution if possible. The tank must be thoroughly rinsed to

remove excess chlorine before reuse.

b. Eliminate dead legs when possible, or install heat tracing to maintain

50°C (122°F) in the lines. Rubber or silicone gaskets provide nutrients

for the bacteria, and removing them will help control growth of the

organism. Frequent flushing of these lines should also reduce growth.

c. Domestic hot-water recirculation pumps should run continuously.

They should be excluded from energy conservation measures.

4.Control.

a. Raising the water-heater temperature can control or eliminate

Legionella growth. Pasteurize the hot water system by raising the

water-heater temperature to a minimum of 70°C (158°F) for 24 hours

and then flushing each outlet for 20 minutes. It is important to flush all

taps with the hot water because stagnant areas can "re-seed" the

system. Exercise caution to avoid serious burns from the high water

temperatures used in Pasteurization.

b. Periodic chlorination of the system at the tank to produce 10 ppm

free residual chlorine and flushing of all taps until a distinct odor of

chlorine is evident is another means of control. In-line chlorinators can

be installed in the hot water line; however, chlorine is quite corrosive

and will shorten the service life of metal plumbing. Control of the pH is

extremely important to ensure that there is adequate residual chlorine

in the system.

c. Alternative means to control Legionella growth include the use of

metal ions such as copper or silver (which have a biocidal effect) in

solution. Ozonization injects ozone into the water. Ultraviolet (UV)

radiation also kills microorganisms. Commercial, in-line UV systems are

effective and can be installed on incoming water lines or on

recirculating systems, but stagnant zones may diminish the

effectiveness of this treatment. Scale buildup on the UV lamp surface

can rapidly reduce light intensity and requires frequent maintenance to

ensure effective operation.

D.DOMESTIC COLD-WATER SYSTEMS.

1.Domestic cold water systems are not a major problem for Legionella

growth. Maintaining cold-water lines below 20°C will limit the potential

for amplification of the bacteria. It is surprising, however, that elevated

levels of Legionella have been measured in ice machines in hospitals.

Cold-water lines near heat sources in the units are believed to have

caused the amplification.

2.Dental water lines have recently been recognized as common sources

of water contaminated with high concentrations of microorganisms

including Legionella. However, to date an increased risk of disease

among dental staff or patients has not been demonstrated. Dental

water line operating conditions are especially appropriate for Legionella

proliferation because the water is stagnant a majority of the time, the

narrow plastic tubing encourages biofilm formation, and the water

temperature is usually 20°C (68°F) or higher--some systems maintain

water at 37°C (98.6°F). Filtration of water at the point of use with

replaceable, in-line, FDA-cleared, 0.22-microns pore sizes filters is

recommended for minimizing risk to patients and staff in a dental

facility.

3.Water tanks that allow water to remain uncirculated for long periods

can also promote growth of bacteria. Such tanks should be eliminated

or designed to reduce storage time to a day or less. They should also

be covered to prevent contamination and protected from temperature

extremes.

4.Cross-contaminations of the domestic cold-water system with other

systems should always be suspected. All connections to process water

should be protected by a plumbing code-approved device (e.g.,

back-flow preventer, air gap, etc.). If significant contamination of the

domestic cold water system occurs, the source of contamination must

be determined. Inspect the system for "dead legs" and areas where

water may stagnate. Elimination of these sections or frequent flushing

of taps to drain the stagnant areas may be necessary to limit growth of

the organism. Insulate cold-water lines that are close to hot-water

lines to reduce the temperature in the line.

5.If the cold-water lines have significant contamination, hyperchlorination

can eradicate Legionella. Free chlorine levels of 20 to 50 ppm are

allowed to remain for one hour at 50 ppm, or two hours at 20 ppm.

Faucets are then allowed to run until the odor of chlorine is present,

and the water is allowed to remain for approximately two hours.

E.HVAC SYSTEMS.

1.HVAC systems are not normally amplification sites for Legionella. The

organism cannot survive without water, and a properly operated,

well-maintained HVAC system is unlikely to be a source of problems.

However, the HVAC system can disseminate contaminated water

aerosols.

2.Water-aerosol sources are classified as either external or internal.

a. External sources may emit contaminated aerosolized water that is

drawn into a system's fresh-air intake. Mist discharged from cooling

towers, evaporative condensers, and fluid coolers can be ingested by

the HVAC fresh air intake. When evaluating this path, you should

consider:

prevailing wind direction and velocity;

building effects (e.g., low-pressure zones on leeward sides of

buildings and on roof);

architectural screen walls; and

distance from tower to intake.

b. Fresh-air intake areaways, typically concrete plenums located at

grade level, supply fresh air to air handlers in the basement or lower

levels of buildings and can collect organic material (e.g. leaves, dirt,

etc.) and water from rain or irrigation.

c. Do not ignore direct paths such as through an open window. The

transmission path through the HVAC system is tortuous, and the

bacteria may die from desiccation in the airstream or impact on internal

surfaces like filters, duct lining, etc. When evaluating external sources,

examine the potential for direct transmission.

d. Internal sources may provide contaminated aerosolized water that is

then disseminated by the air-distribution system. Contaminated water

can leak from pipes into HVAC ducts, where it can be aerosolized and

distributed by the system. Potential sources of contaminated water

include domestic water systems, fire-sprinklers, refrigeration

condensers, etc.

e. HVAC system humidifiers can be hazards. Four types are common:

Heated-pan humidifiers use a heat source to evaporate water

from a pan open to the air stream. Intermittent use of the device

coupled with a warm pan of water may support Legionella growth.

Contaminant-free water is essential.

Direct steam-type humidifiers inject boiler-generated steam

directly into the air stream. These systems normally operate

above 70°C (158°F), and Legionella cannot survive at that

temperature.

Atomizing humidifiers use mechanical devices or pneumatic air to

create a water mist that evaporates into the air stream. A

contaminant-free water source is essential.

f. Direct evaporative air coolers may be used as humidifiers. These

devices mix water and air in direct contact to create a cool, wet air

stream by evaporation. These devices include sumps, which may

stagnate when not in use.

g. When draining properly, the water that passes through the

condensate pans of cooling coils in an air handler is normally not a

source of growth for the organism because of the low temperature of

water condensate.

h. Indirect evaporative air cooling in systems designed for dryer

climates. One common design circulates cool water from a cooling

tower sump through a water coil in the supply air stream. If the coil

develops a leak, then pumped cooling tower water will be injected

directly into the supply air stream with potentially deleterious effects if

the sump water is contaminated with Legionella. Indirect evaporative

air cooling is also found in air-to-air heat exchangers. One side of the

heat exchanger is an evaporative-cooled wet air stream, and the other

side supplies air for the conditioned space. If the heat exchanger leaks,

the wet air stream can mix with supply air and cause problems if the

wet air stream is contaminated with Legionella.

i. Many air-handling systems designed for dryer climates employ direct

evaporative air cooling. Wet evaporative coolers, slinger air coolers and

rotary air coolers common in commercial applications. These devices mix

water and air in direct contact to create a cool, wet air stream by

evaporation. If these systems are using 100% outside air in a dry

climate, the water sump temperature may be low and will not represent

a significant risk. However, improperly operated and maintained systems

that use warm, stagnant sump water can present problems.

j. Other equipment may also be potential sources of Legionella:

Residential humidifiers are small, free-standing, portable units that

use an internal fan and wet media to disseminate a wet air

stream. The sumps of these devices are frequently contaminated

with Legionella. Daily cleaning is necessary to maintain

acceptable water quality, but these units seldom receive

appropriate maintenance, and their use in the commercial or

industrial workplace is strongly discouraged.

Computer room air conditioners typically include humidifiers and

frequently are not well maintained. They may contain a sump

filled with contaminated water.

3.The following are issues to consider when designing HVAC systems to

minimize risk from Legionella contamination. Most apply to all types of

microbial contamination.

a. Minimize use of water reservoirs, sumps, and pans. Chemically

untreated, stagnant, warm-water sources provide an ideal environment

for Legionella growth.

b. Provide a way to drain water sumps when not in use, e.g., an

electric solenoid valve on the sump drain. If an HVAC sump is used

during the hours when a building is occupied, drain the sump during

unoccupied hours.

c. Provide a "bleed" for water sumps so that dissolved solids do not

form sediments in the sump.

d. Slope and drain sumps from the bottom so that all the water can

drain out and allow the pan to dry.

e. Locate HVAC fresh-air intakes so that they do not draw the mist

from a cooling tower, evaporative condenser, or fluid cooler into the

system. The American Conference of Governmental Industrial Hygienists

publishes "Guidelines For The Assessment Of Bioaerosols In The Indoor

Environment," which lists recommended minimum distances between

cooling towers and fresh-air intakes.

f. Design indirect evaporative cooling systems with the knowledge that

the failure of the heat exchanger will allow wet systems to mix with the

air-distribution systems.

g. Use steam or atomizing humidifiers instead of units that use

recirculated water. Do not use raw steam from the central heating

boiler because it contains corrosion inhibitors and anti-scaling

chemicals. Atomizing humidifiers must have contaminant-free water.

4.Operate all HVAC equipment as originally designed, and maintain it so

that it can perform as designed. Test all HVAC equipment periodically to

insure that it is performing as designed. Inactive sumps must be

properly drained and bled to prevent accumulation of sediments.

Maintenance failures can produce contaminated, stagnant water that

can become an ideal environment for Legionella growth if heated (e.g.,

by sunlight).

VI.BIBLIOGRAPHY.

American Water Works Association, A Procedure for Disinfecting Water Mains AWWA C601

1981; Denver CO.

Best, M., A. Goetz, and V.L. Yu. "Heat eradication measures for control of nosocomial

Legionnaires' disease." American Journal of Infection Control, 12, (1), 1984, pp. 26-30.

Broadbent, C.R. "Legionella in Cooling Towers: Practical Research, Design, Treatment and

Control Guidelines." Delivered at 1992 Inter. Symp. on Legionella, Amer. Society for

Micro., Jan. 26-29, 1992, Orlando Fl.

Chartered Institution of Building Services Engineers, Minimizing The Risk of Legionnaires'

Disease, Delta House, 222 Balham High Rd., London 1987.

England, A.C. et al. "Sporadic legionellosis in the U.S.: the first 1000 cases." Ann. Inter.

Med. 94, 1981, p. 164.

Gilpin, R.W., A.M. Kaplan, and E.F. Goldstein "Quantitation of Legionella pneumophila in

one thousand commercial and industrial cooling towers." Proceedings 48th Inter. Water

Conference, Oct. 24-26, 1988, Pittsburgh, pp.13-19.

Health and Safety Executive (UK), "The Control of legionellosis including Legionnaires'

disease." Health and Safety Series Booklet, HS (G)70, Library and Information Services,

Broad Lane, Sheffield S37HQ, Tel: (0742) 752539.

Health Department Victoria; Melbourne Australia, "Guidelines for the Control of

Legionnaires' Disease" in Environmental Health Standards, 1989.

Morris, G.K. and B.G. Shelton. Legionella in Environmental Samples: Hazard Analysis and

Suggested Remedial Actions. March 1991, Pathogen Control Assoc., Norcross, Georgia.

Muder, R.R., V.L. Yu, and A.H. Woo. "Mode of transmission of Legionella pneumophila."

Arch Intern Med, 146, (1986), pp. 1607-1612.

Muraca, P., J.E. Stout, and V.L. Yu. "Comparative assessment of chlorine, heat, ozone,

and UV light for killing Legionella pneumophila within a model plumbing system." Applied

and Environmental Microbiology, 53, (2), 1987, p. 447-453.

Muraca, P.W., V.L. Yu, and R.N. Goetz. "Disinfection of water distribution systems for

Legionella: a review of application procedures and methodologies." Infect. Control Hosp.

Epidemiol., 11, (2), 1990, pp. 79-88.

Muraca, P.W., J.E. Stout, V.L. Yu, and Y.C. Ying. "Legionnaires' disease in the work

environment: implications for environmental health." Am. Ind. Hyg. Assoc., 49, (11), 1988,

pp. 584-590.

Nalco Chemical Company. Cooling Water Chlorination, Technifax, TF-132, Nalco Chemical

Co., Naperville, Illinois, 1986.

Nguyen, M.H., J.E. Stout, and V.L. Yu. "Legionellosis." Lower Respiratory Tract

Infections, 5, (3), September 1991, pp. 561-584.

Stout, J.E., V.L. Yu, and M.S. Muraca. "Isolation of Legionella pneumophila from the cold

water of hospital ice machines: implications for origin and transmission of the organism."

Infection Control, 7786, (4), 1985, pp. 141-146.

Stout, J.E., V.L. Yu, M.S. Muraca, J. Joly, N. Troup, and L.S. Tompkins. "Potable water as

a cause of sporadic cases of community-acquired Legionnaires' disease." New England

Journal of Medicine, 326, January 16, 1992, pp. 151-155.

Wisconsin Division of Health. Control of Legionella in Cooling Towers: Summary

Guidelines, June 1987, Wisconsin Department of Health and Social Sciences.

Williams, J.F. et. al. "Microbial contamination of dental unit waterlines: prevalance,

intensity and microbiological characteristics." J. of American Dental Association, 124,

October 1993, pp. 59-65.

APPENDIX III:7-1. EMPLOYEE AWARENESS PROGRAM.

The purpose of an employee awareness program is to inform the employees of the

potential outbreak, and to educate them about the disease. This educational program

should be part of a level-two investigation or for a Legionnaires' disease outbreak. This

program is of critical importance to aid in early recognition of the disease. It is also

important to help alleviate employee concerns about the disease. This program should

supplement the case identification program to discover previously undetected cases of

the illness at the work site.

The employer should implement the following elements of this program immediately upon

recognition of more than one probable or confirmed case of disease in the work place:

An initial employee training session which provides basic information about the

disease and actions being taken to investigate the problem;

An ongoing general information service to provide updates and answer questions

that may arise among employees; and

Medical and psychological counseling services when an outbreak has occurred.

Below is a sample letter and supplemental information on the disease that the

employer can use for informing employees of a potential or actual outbreak.

SAMPLE LETTER FROM EMPLOYER TO EMPLOYEES

DATE:

MEMO TO: ALL EMPLOYEES

FROM: MANAGEMENT OFFICIAL

SUBJECT: Legionnaires' Disease

On _________________, we were notified that one of the employees of our

company had contracted legionellosis, commonly referred to as Legionnaires'

disease. The employee is assigned to _________________ on ___________

shift.

We want to share with you some general information concerning the disease.

In addition, we want to tell you what we are currently doing here at

_____________________ to ensure all necessary steps are taken to address

health concerns.

Legionellosis, or Legionnaire's disease, is a type of pneumonia caused by

Legionella bacteria. Legionnaires' disease is not contagious, and you cannot

catch it from another person. The bacteria are common and grow in water.

People often receive low-level exposure in the environment without getting

sick. Legionellosis usually occurs only when someone who is already susceptible

receives concentrated exposure to the bacteria. Persons who are heavy

smokers, elderly, or whose ability to resist infection is reduced are more likely

to contract Legionnaires' disease than healthy nonsmokers. According to the

Centers for Disease Control in Atlanta, there are between 10,000 and 50,000

cases of Legionnaire's disease every year in the U.S. We are cooperating fully

with local health officials who are investigating this matter. Most cases of

legionellosis are isolated and are not associated with an outbreak. To date,

_____ case(s) of the disease has/have occurred among employees in this

facility.

To identify any other cases, we will review sick-leave records for the period

____________ to _____________. Employees who took more than three

consecutive days of sick leave will be identified, and we will attempt to

determine if any in that group experienced pneumonia-like symptoms (fever,

shortness of breath, cough). Those who used three or more consecutive days

of sick leave during this period can expect to be contacted by a representative

of our company for an interview. If you experienced a pneumonia-like illness in

the past two months but used fewer then three consecutive days of sick

leave, contact _________________ to arrange an interview.

To assure that you are being protected during the interim, we are also

instituting a medical surveillance program to identify any new or old cases. Part

of this surveillance will be to ask you a few questions about your illness when

you call in sick to your supervisor. In addition, we are offering counseling and

employee information services. If you would like to take advantage of these

services or want more information, contact your manager. For the present,

please pay attention to the following important points:

WHAT YOU SHOULD DO NOW:

1.If you are not sick, there is no need for you to see a doctor.

2.If you are now sick with a cough and fever:

A.See your private doctor or contact __________ to arrange to see

a _______________ physician.

B.Tell the physician that you work in a building that may be involved

in a Legionnaires' disease outbreak.

C.If you see a physician, notify _______________ so that your illness

can be tracked.

If you have any concerns or questions concerning this issue, please ask your

manager. Your health and safety are of great concern to us, and we will be

grateful for your cooperation in this matter. As further information develops we

will keep you informed.

SAMPLE INFORMATION TO BE OBTAINED BY INTERVIEW

WITH EMPLOYEES CALLING IN ON SICK LEAVE

Interviewer:__________________________Date:_______________

SUPERVISOR SURVEY FORM

We are screening employee illnesses as a result of our Legionnaire's disease

incident. You are not obligated to participate in the survey, but your participation

will help you and your fellow workers.

We recommend that you see a physician if you currently have pneumonia-like

symptoms such as severe chills, high fever, a cough, and difficult breathing.

Are you currently experiencing these symptoms?

Yes_____ No_____ Prefer not to answer______

If the answer to the question is "No," do not complete the rest of this form.

Thank you for your cooperation.

If the answer is "Yes," please read the statement below and complete the

bottom half of this form (Employee name, etc).

If you answer is "Prefer not to answer," please complete ONLY the bottom

half of this form (Employee name, etc).

STATEMENT: You will be contacted by ______________ to obtain additional

information necessary to complete our survey.

Thank you!

Employee's Name _______________________________________________

Work Telephone Number _______________________________

Home Telephone Number _______________________________

Shift: Day ___ Swing ___ Graveyard ___ Rotating ___

Branch _______________________/Organization Code _______________

Employee's Supervisor _____________________________________________

Telephone Number _______________________________________________

Date _____________________________________

PLEASE FORWARD TO ________________ BY 10:00 am EACH DAY

LEGIONNAIRES' DISEASE: QUESTIONS AND ANSWERS

BACKGROUND.

Legionnaires' disease is a common name for one of the several illnesses caused by

Legionella bacteria. Legionnaires' disease is an infection of the lungs that is a form of

pneumonia. A person can develop Legionnaires' disease by inhaling water mist

contaminated with Legionella.

Legionella bacteria are widely present at low levels in the environment: in lakes, streams,

and ponds. At low levels the chance of getting Legionnaires' disease from a water source

is very slight. The problem arises when high concentrations of the organism grow in water

sources. Water heaters, cooling towers, and warm, stagnant water can provide ideal

conditions for the growth of the organism.

Scientists have learned much about the disease and about the Legionella bacteria since it

was first discovered in 1976. The following questions and answers will help you learn more

of what is currently known about Legionnaires' disease.

Q.What are the symptoms of Legionnaires' disease?

A.Early symptoms of the illness are much like the flu. After a short time (in some

cases a day or two), more severe pneumonia-like symptoms may appear. Not all

individuals with Legionnaires' disease experience the same symptoms. Some may

have only flu-like symptoms, but to others the disease can be fatal.

Early flu-like symptoms:

slight fever

headache

aching joints and muscles

lack of energy, tired feeling

loss of appetite

Common pneumonia-like symptoms:

high fever (102° to 105°F, or 39° to 41°C)

cough (dry at first, later producing phlegm)

difficulty in breathing or shortness of breath

chills

chest pains

Q.How common is Legionnaires' disease?

A.It is estimated that in the United States there are between 10,000 and 50,000

cases each year.

Q.How does a person get Legionnaires' disease?

A.A person must be exposed to water contaminated with Legionella bacteria. This

exposure may happen by inhaling or drinking water contaminated with the Legionella

bacteria. For example, inhaling contaminated water mist from a cooling tower, a

humidifier, or even a shower or sink can cause the disease.

Q.How soon after being exposed will a person develop symptoms of the disease?

A.If infection occurs, disease symptoms usually appear within 2 to 10 days.

Q.Are some people at a higher risk of developing Legionnaires' disease?

A.Yes, some people have lower resistance to disease and are more likely to develop

Legionnaires' disease. Some of the factors that can increase the risk of getting the

disease include:

organ transplants (kidney, heart, etc.);

age (older persons are more likely to get disease);

heavy smoking;

weakened immune system (cancer patients, HIV-infected individuals);

underlying medical problem (respiratory disease, diabetes, cancer, renal

dialysis, etc.);

certain drug therapies (corticosteroids); and

heavy consumption of alcoholic beverages.

Q.Is Legionnaires' disease spread from person to person?

A.No. Legionnaires' disease is not contagious and cannot be transmitted from one

person to another.

Q.What causes Legionnaires disease?

A.Legionnaires' disease is caused by inhaling water contaminated with rod-shaped

bacteria called Legionella pneumophila. There are over 30 different species of

Legionella, many of which can cause disease. Legionella pneumophila is the most

common species that causes disease.

Q.Does everyone who inhales Legionella into the lungs develop Legionnaires' disease?

A.No. Most people have resistance to the disease. It is thought that fewer than 5 out

of 100 persons exposed to water contaminated with Legionella will develop

Legionnaires' disease.

Q.Is Legionnaires' disease easy to diagnose?

A.No. The pneumonia caused by Legionella is not easy to distinguish from other forms

of pneumonia. A number of diagnostic tests allow a physician to identify the

disease. These tests can be performed on a sample of sputum, blood, or urine.

Q.How is Legionnaires' disease treated?

A.Erythromycin is currently the antibiotic of choice. Early treatment reduces the

severity and improves chances for recovery. In many instances this antibiotic may

be prescribed without the physician's knowledge that the disease is Legionnaires'

because erythromycin is effective in treating a number of types of pneumonia.

Q.How did Legionnaires' disease get its name?

A.Legionnaires' disease got its name from the first outbreak in which the organism

was identified as the cause. This outbreak occurred in 1976, in a Philadelphia hotel

where the Pennsylvania American Legion was having a convention. Over 200

Legionnaires and visitors at this convention developed pneumonia, and some died.

From lung tissue, a newly discovered bacterium was found to be the cause of the

pneumonia and was named Legionella pneumophila.

Q.Is Legionnaire's disease a new disease?

A.No, Legionnaires' disease is not new, but it has only recently been identified.

Unsolved pneumonia outbreaks that occurred before 1976 are now known to have

been Legionnaires' disease. Scientists are still studying this disease to learn more

about it.

Q.Are Legionella bacteria widespread in the environment?

A.Yes, studies have shown that these bacteria can be found in both natural and

man-made water sources. Natural water sources including streams, rivers,

freshwater ponds and lakes, and mud can contain the organism in low levels.

Q.Could I get the disease from natural water sources?

A.It is unlikely. In the natural environment the very low levels of this organism in

water sources probably cannot cause disease.

Q.What water conditions are best for growth of the organism?

A.Warm, stagnant water provides ideal conditions for growth. At temperatures

between 68° and 122°F the organism can multiply. Temperatures of 90°-105°F are

ideal for growth. Rust (iron), scale, and other micro-organisms can also promote the

growth of Legionella.

Q.What common types of water are of greatest concern?

A.Water mist from cooling towers or evaporative condensers, evaporative coolers

(swamp coolers), humidifiers, misters, showers, faucets, and whirlpool baths can be

contaminated with the organism and if inhaled or swallowed can cause the disease.

Q.Can Legionnaires' disease be prevented?

A.Yes. Avoiding water conditions that allow the organism to grow to high levels is the

best means of prevention. Specific preventive steps include:

Regularly maintain and clean cooling towers and evaporative condensers to

prevent growth of Legionella. This should include twice-yearly cleaning and

periodic use of chlorine or other effective biocide.

Maintain domestic water heaters at 140°F (60°C). The temperature of the

water should be 122°F or higher at the faucet.

Avoid conditions that allow water to stagnate. Large water-storage tanks

exposed to sunlight can produce warm conditions favorable to high levels of

Legionella. Frequent flushing of unused water lines will help alleviate

stagnation.

Q.Do you recommend that I operate my home water heater at 140°F?

A.Probably not if you have small children or infirm elderly persons who could be at

serious risk of being scalded by the hot water. However, if you have persons living

with you who are at high risk of contracting the disease, then operating the water

heater at a minimum temperature of 140F is probably a good idea.

Q.What can be done if a water system is already contaminated or is suspected of

being contaminated?

A.Special cleaning procedures can eliminate Legionella from water sources. In many

cases these procedures involve the use of chlorine-producing chemicals or high

water temperatures. Professional assistance should be sought before attempting to

clean a water system.

Q.Can my home water heater also be a source of Legionella contamination?

A.Yes, but evidence indicates that smaller water systems such as those used in

homes are not as likely to be infected with Legionella as larger systems in work

places and public buildings.

Q.Can Legionella bacteria cause other diseases?

A.Yes. In addition to Legionnaires' disease, the same bacteria also cause a flu-like

disease called Pontiac fever.

Q.How does Pontiac fever differ from Legionnaires' disease?

A.Unlike Legionnaires disease, which can be a serious and deadly form of pneumonia,

Pontiac fever produces flu-like symptoms that may include fever, headache,

tiredness, loss of appetite, muscle and joint pain, chills, nausea, and a dry cough.

Full recovery occurs in 2 to 5 days without antibiotics. No deaths have been

reported from Pontiac fever.

Q.Are there other differences between Legionnaires' disease and Pontiac fever?

A.Yes. Unlike Legionnaires' disease, which occurs in only a small percentage of

persons who are exposed, Pontiac fever will occur in approximately 90% of those

exposed. In addition, the time between exposure to the organism and appearance

of the disease (called the incubation period) is generally shorter for Pontiac fever

than for Legionnaires' disease. Symptoms of Pontiac fever can appear within one to

three days after exposure.

APPENDIX III:7-2. PHYSICAL SURVEY AND WATER SAMPLING ROTOCOL.*

Arrange with the appropriate laboratory for supply and shipment of sterile sampling

containers, and for analysis of water samples. During the initial walk-through, estimate

the size of the building and the number of water services at the facility to determine the

number of samples and the size of the purchase order. When investigating the water

services within a building, it will be helpful to obtain or prepare a simple schematic

diagram of the water services. Note the following features:

The location of the incoming supply and/or private source.

The location of storage tanks, water treatment systems, and pumps.

The location of water heaters and boilers.

The type of fittings used in the system (e.g., taps, showers, valves) and the

material from which the pipework is made.

The location of all cooling towers, evaporative condensers, and fluid coolers at the

facility. The location and type of all systems served by the cooling tower water

including sump tanks, condensers, and indirect evaporative cooling coils in air

handling units.

The location of any evaporative cooling systems or humidifiers.

The location of ornamental fountains, whirlpools, eye washes, safety showers, or

other water sources within or near the facility.

Trace the route of the service from the point of entry of the water supply. Note the

condition of pipes, jointing methods used, insulation, sources of heat, and the kind of

insulation in water storage tanks. Also note carefully any disconnected fittings, "dead

legs," and cross-connections with other services. Once you have identified these

features, take water samples from:

The incoming water supply.

Each storage tank and water heater.

A representative number of faucets for each of the hot and cold water systems in

the facility.

All cooling towers, evaporative condensers, humidifiers, spas, showers, etc.

The water entering or leaving any other type of fitting or piece of equipment under

particular suspicion.

It is important not to overlook any potential water sources in the building. Water from ice

machines, hand spray bottles, decorative fountains, and for plastic injection molding

equipment have been implicated in past outbreaks or have been found to be significantly

contaminated. The ability to maintain an open mind is essential in conducting an

investigation because of the variety of potential sources of contamination at a facility.

WATER SAMPLING PROCEDURE.

Wear appropriate respiratory protection in the form of a half-face piece respirator

equipped with a HEPA filter or a similar type of filter media capable of effectively

collecting particles in the one micron size range during the examination of water systems

if a significant potential exists for exposure to high concentrations of contaminated

aerosols.

Collect samples in polypropylene (nalgene) containers (250 mL-1 L) that have been

autoclaved at 121°C for 15 minutes. The microbiological laboratory that will analyze the

samples should be able to provide the bottles. A local hospital or state health department

should be able to autoclave the bottles. It is important not to flush the system to be

sampled before collecting samples. Collect at least a 250 mL sample. Measure the

temperature of the sampled water. It is preferable to accomplished this by measuring the

water stream flowing from the water source and not by placing the thermometer in the

sample container. To avoid cross-contamination of the samples, sanitize the thermometer

with isopropyl alcohol before measuring the temperature of each sample. When measuring

temperature from faucets, showers, water fountains, etc., record the initial water

temperature, and then allow the fixture to discharge until the temperature stabilizes.

Record the initial and final temperatures, and the time needed to stabilize.

Domestic Water Heaters.

Take a sample of water from the bottom drain.

Collect a sample of water from the outlet pipe if the plumbing provides for access.

Faucets and Showers.

Collect a "before-flush" (initial flow) sample of water.

Collect an "after-flush" sample of water when the maximum temperature has been

reached.

The initial (before-flush) sample is intended to indicate the level of contamination at the

sample point or fitting, and the final sample should reveal the quality of the water being

supplied to the fitting. Collect sterile-swab samples from faucets or shower heads by

removing the fitting and vigorously swabbing the interior. Swab samples may be positive

for Legionella even when water samples from the source are negative. Sterile test tubes

containing sterilized swabs are available for convenient sampling and shipping.

Cooling Towers.

Take a sample from the incoming supply to the tower.

Take samples from any storage tanks or reservoirs in the system (i.e., chilled-water

return tanks or header tanks).

Take a sample from the basin of the cooling tower at a location distant from the

incoming make-up water, and from the water returning from the circulation system

at the point of entry to the tower.

Take a sample of any standing water in the condensate trays or from the cooling

coils.

Humidifiers, Swamp Coolers, and Spas.

Take a sample from the water reservoirs. Sample the incoming water supply if it is

accessible.

For cooling towers, humidifiers, swamp coolers, and building water services, collect

samples of sludge, slimes, or sediments, particularly where accumulations occur.

Take swabs of shower heads, pipes, and faucets and rehydrate from water taken

from the sampling site. Swab areas of scale buildup (i.e., remove shower heads,

faucet screens, and aerators). Use prepackaged sterile swabs and small glass or

polypropylene bottles (autoclaved) for this purpose.

SAMPLE TRANSPORTATION.

Prepare samples for shipment carefully, as follows:

Wrap vinyl tape clockwise around the neck of each bottle to hold its screw cap

firmly in place and seal the interface between the cap and the bottle.

Wrap absorbent paper around bottles, and place the bottles in a sealable (zip-lock)

plastic bag.

Place the sealed plastic bag in an insulated container (styrofoam chest or box).

Samples should not be refrigerated or shipped at reduced temperature. They should be

protected from temperature extremes such as sunlight or other external heat or cold

sources. Ship to laboratory using overnight mail. If shipping on a Friday, make

arrangements for weekend receipt. The samples should be stored at room temperature

(20° ± 5°C) and processed within 2 days.

APPENDIX III:7-3. WATER SAMPLING GUIDELINES.

[Adapted from George K. Morris, PhD, and Brian G. Shelton, Pathcon Technical Bulletin

1.3, Legionella in Environmental Samples: Hazard Analysis and Suggested Remedial

Actions, June 1991, Pathogen Control Associates, 270 Scientific Dr., Suite 3, Norcross,

GA 30092]

Use the following guidelines to assess the effectiveness of water system maintenance.

These guidelines are based on limited data and are subject to change. They are intended

to apply only to water systems being used by healthy individuals and are not necessarily

protective for persons who are immunocompromised.

The levels requiring action vary for the source of exposure based on the assumption that

some routes or exposure result in a greater dose to the lung. For this reason, humidifiers

and similar devices such as misters and evaporative condensers which produce an aerosol

mist that can be directly inhaled should be controlled to lower levels. Remember that

these numbers are only guidelines, and the goal is zero detectable Legionella in a water

source. Levels of Legionella equal to or greater than the values in the table constitute a

need for action, as described below.

Action 1: Prompt cleaning and/or biocide treatment of the system.

Action 2: Immediate cleaning and/or biocide treatment. Take prompt steps to prevent

employee exposure.

Table III:7-1. Colony forming units (CFU) of Legionella per milliliter

Action

1

2

Cooling tower

100

1,000

Domestic water

10

100

Humidifier

1

10

APPENDIX III:7-4. LEGIONNAIRES' DISEASE CASE IDENTIFICATION.

The purpose of this phase of an investigation will be to identify cases of Legionnaires'

disease among the workers. The investigation will include identification of all employees

who took three or more consecutive days of sick leave days from six weeks before the

Legionnaires' case was identified to the present. Following a screening process, all

employees who have been identified as having had pneumonia, or potentially having had

pneumonia, during this period will be requested to undergo voluntary medical testing to

detect evidence of Legionnaires' disease. A physician's diagnosis of pneumonia or

pneumonia-like symptoms that include a fever (101°F) and cough indicate a need for

further evaluation. A sample program is described below.

Examine sick leave records to identify all employees who used three or more consecutive

days of sick leave from 6 weeks before the earliest known case to the present. These

employees will be interviewed. If it appears that an employee experienced a

pneumonia-like illness, the attached surveillance questionnaire will be completed.

Employees who feel that they might have had symptoms of Legionnaires' disease but did

not use three or more consecutive days of sick leave should also be interviewed.

Employees who have experienced a pneumonia-like illness and have seen a physician

should be requested to sign a medical release form to allow the company and/or OSHA to

obtain additional information from the physician. The physicians of all employees who

have seen a physician and have signed a medical release will be interviewed using the

physician interview survey form (attached).

Employees participating in surveys such as the one described above must be informed of

their Privacy Act rights as well as their right to protect their own medical information.

Physician-patient confidentiality must not be violated. Necessary medical information may

be communicated only with the patient's written permission. When seeking employees'

permission, clearly inform them that the purpose of obtaining a proper diagnosis and

sharing this information with the Agency is to protect them and their fellow workers

against the potential threat of legionellosis. All medical records will be handled in

accordance with 29CFR 1913.10. It may be necessary for the CSHO to obtain medical

releases from the employees interviewed so that amplifying information can be obtained

from a company health unit or the employee's physician.

Arrangements similar to that described above should be sought for permanent contract

employees controlled by separate contractor organizations in the building, e.g., janitors,

cafeteria workers, security personnel.

Based on an interview with the employee's physician, potential cases should be

considered for a clinical test to detect additional cases. Most probably this will be a

serological test to determine the antibody level of the individual. A single antibody titer of

1/256 or greater based on a physician's diagnosis of pneumonia should be interpreted as a

probable case of Legionnaires' disease. In the event that an antibody titer level for

Legionella was obtained at the time of illness, or if serum collected from the patient at

the early phase of the illness (acute phase) is available, then an antibody titer level

should be determined from this sample to determine the convalescent to acute titer ratio.

A fourfold increase in this titer will be sufficient to confirm a case of Legionnaires'

disease.

Other diagnostic tests may also be appropriate. If the potential case occurred recently,

then a urine antigen test may detect Legionella pneumophila serogroup-1 antigen. A

positive urine antigen test for a diagnosed pneumonia case is also accepted as evidence

of a confirmed case. However, this test is available only for Legionella pneumophila

serogroup-1 infections. Culture currently symptomatic individuals for Legionella. A positive

culture indicates confirmation.

If this process detects one or more additional cases of disease, then the facility should

be considered to have experienced an outbreak. The immediacy of the action will depend

on whether the outbreak is ongoing or occurred 30 days or more in the past. Take prompt

action to control exposure at the site if there is evidence that the outbreak is still

occurring. Whatever the circumstances, initiate control procedures and continue medical

surveillance of the workforce to detect any new cases of disease and identify the water

source responsible for the outbreak.

HEALTH SURVEILLANCE QUESTIONNAIRE - LEGIONELLOSIS

Records show that you took sick leave for three consecutive days or more. We

would like to ask a few questions.

1.Name: (last)____________________, (first)__________________

Age:______ Sex: ______ Work Location: ____________________

Home Phone:___________ Work Phone:________________________

2.Dates of absence(s):______________________________________

3.Stated reason for absence:________________________________

Ask about the following symptoms:

4.Fever: Yes ____ No____ If yes, highest temperature _____.

5.Cough: Yes____ No ____

6.Headache: Yes_____ No_____

7.Diarrhea: Yes_____ No_____

8.Shortness of breath: Yes ____ No ____

9.Chest pain: Yes ____ No ____

10.Did you see a physician about these symptoms? Yes ___ No ___

Was a chest x-ray taken? Yes_____ No_____

Were you diagnosed as having pneumonia? Yes ___ No ___

Were you tested for legionellosis? Yes_____ No_____

Physician's name:______________________ Phone:_____________

Physician's Address:______________________________________

11.Were you admitted to a hospital? Yes ____ No ____

If yes, which hospital?_____________________________________

Admission Date: _________________ Date released: __________

12.Interviewer:________________________________ Date:______________

PHYSICIAN SURVEY QUESTIONNAIRE - LEGIONELLOSIS

We are calling to inform you that _______________________ is a patient of

yours and an employee at ____________. He/she has signed a medical release

giving us permission to contact you to obtain information about her/his recent

illness. This questionnaire will be used to determine if your patient's recent

illness could be classified as a pneumonia that may have been caused by

exposure to Legionella at the workplace.

1.Name of Physician: ________________________________________

Address:___________________________________________________

Phone:_____________________________

2.Date of visit(s): (1st)________ (2nd)________ (3rd)________

3.What was the patient's complaint?:_________________________

___________________________________________________________

Cough?

Short of breath?

History of fever?

yes

yes

yes

no

no

no

unknown

unknown

unknown

4.Physical Findings: _________________________________________

____________________________________________________________

Abnormal chest or lung findings: ___________________________

____________________________________________________________

Rales?

Dyspnea?

Cyanosis?

yes

yes

yes

no

no

no

not examined

not examined

not examined

Temperature ______

Other: __________________________________________________

5.Chest x-ray done? yes no

Findings: _____________________________________________

6.Sputum culture? yes no

Results: ______________________________________________

Laboratory: ___________________________________________

Sputum cultured for Legionella? yes no

Laboratory:___________________________________________

7.Diagnostic testing? yes no

Type of test: Urine Antigen Test, Direct Fluorescent Antibody

Serology Tests:

Indirect Fluorescent Antibody (IFA) ______

ELISA ________

Laboratory:____________________________________________

8.Diagnosis or impression: _____________________________________

EPIDEMIOLOGICAL QUESTIONNAIRE

Background

Employee's Name:_________________________ Age:_____ Gender:_____

(last, first)

Home:_____________________________________________________________

(city, zip)

Race/Ethnicity: white, black, native American, Hispanic, Asian, Other (circle

one)

Are you currently taking any oral steroid medications?: Y/N

On what date did you first become ill?: ___ /___ /___

How many days were you ill?: _______

Was anyone else in your family ill?: Y/N

If Yes, who? ______________________________________

What symptoms did they have? ______________________________

Since ___________, have any of your friends been diagnosed with pneumonia?:

Yes/No

If Yes, who? _______________________________________________

Work Exposure

During the 10 days prior to your illness:

Job Description: ________________________________________________

Primary work area: ______________________________________________

List all areas in _______ building where you spend any time:

Area

_______________________________

_______________________________

_______________________________

_______________________________

_______________________________

Hours per week

_______________________________

_______________________________

_______________________________

_______________________________

_______________________________

Did you shower at work?: Yes/No

If Yes, where and how may times per week?: _________________

List all places you eat lunch:____________________________________

List all places where you take a break: ____________________________

List all restrooms you use: ________________________________________

Do you smoke in the restrooms (or spend "extra" time, i.e., if a lounge is

present): Yes/No

If Yes, Where:_______________________________

Did you attend any training courses outside of the building?: Yes/No

If Yes, where were they held? _______________________________

Do you have a second job?: Yes/No

If Yes, what job and where:

____________________________________________________________________

Any other places that you have not mentioned where you spend time while on

the job?:

____________________________________________________________________

Community Exposure (During the 10 days prior to your illness)

Did you use any health clubs?: Yes/No

If Yes, which ones?: ________________________________________

How many times?______________________________________________

Did you use any hot tubs (whirlpool spas)?: Yes/No

If Yes, list which hot tubs and when used:

_____________________________________________________________

Did you attend any churches?: Yes/No

If Yes, where________________________________________________

How many times?____________

Have you had any dental work performed?: Yes/No

If Yes, where_________________________________________

How many times?____________

Which grocery stores did you go to?: _____________________________

How often?__________________

Did you go to the movies?: Yes/No

If Yes, which one? ________________________________

How often?____________

Did you go to any shopping malls?: Yes/No

If Yes, which one(s)?__________________________

Did you go to any other public places which you feel might be significant (i.e.

public meetings, schools etc.)?: Yes/No

If Yes, where? ___________________________________________

APPENDIX III:7-5. WATER TREATMENT PROTOCOLS FOR FACILITIES THAT HAVE

EXPERIENCED A LEGIONNAIRES' OUTBREAK.

BACKGROUND.

This section describes actions required to abate the threat of further infection in a

building in which an outbreak of Legionnaires' disease has occurred. For purposes of this

document, an "outbreak of Legionnaires' disease" may be said to exist when medically

confirmed cases of Legionnaires' disease are epidemiologically associated with a building

or some portion of a building. This usually means that two or more confirmed cases of

Legionnaires' disease have been identified within a six-week period at the site.

Under most circumstances evacuation of the building is not recommended. It will be

necessary, following confirmation of an outbreak, to isolate individuals who are at high

risk of contracting the disease from all potential sources of infection. Individuals at high

risk include the immunosuppressed, such as persons who have had organ transplants,

individuals receiving chemotherapy including corticosteroids, and other individuals in poor

health. In addition, a medical monitoring program must be instituted to track all workers

currently on sick leave.

Following these initial actions, the building must be inspected to identify all potential

Legionella sources including the HVAC cooling systems (cooling towers, evaporative

condensers), domestic water systems, humidifiers, and any sources of water that are

maintained above 20°C (68°F) and has a potential for being aerosolized.

Before flushing or disinfecting the water in these suspected sources, take water samples

for analysis to determine the predominant serotypes and subtypes of L. pneumophila in

the water source and to determine the number of colony forming units (CFU) per unit of

water. This information will be helpful in identifying the source of the disease if the

subtype of L. pneumophila has been identified in the afflicted worker population. Because

of the 10-day to two-week delay in obtaining sample results, corrective action should

begin immediately.

Because sampling for Legionella can be inconclusive, sampling results alone should not

determine the appropriate course of action in a building where an outbreak has occurred.

ALL POTENTIAL SOURCES OF CONTAMINATION WILL BE ASSUMED TO BE CONTAMINATED

AND TREATED ACCORDINGLY IN THE EVENT THAT AN OUTBREAK HAS OCCURRED. Water

sampling and testing must be in accordance with currently accepted, state-of-the-art

procedures.

Treatment of potential sources of contamination following sampling is described below.

After the treatment collect and analyze water samples for CFU of L. pneumophila to

determine the effectiveness of the treatment. Upon re-use of a water system following

treatment, periodic maintenance and regular water sampling are essential to ensure that

the maintenance continues to be effective. Included are proper maintenance procedures

for controlling the organism in a facility's water sources.

COOLING TOWERS AND EVAPORATIVE CONDENSERS.

An HVAC condenser water system absorbs heat from the AC refrigeration units and

rejects it to the atmosphere through evaporation in cooling towers. Evaporative

condensers operate similarly to cooling towers except that refrigerant coils are inside the

water path, and water passes over the coils to cool the refrigerant gas directly. Because

both cooling towers and evaporative condensers use a fan system to move air through a

recirculated water system, they introduce a considerable amount of water vapor into the

surroundings even with drift eliminators designed to limit vapor release. In addition, this

water is typically in the 20°-50°C (68°-122°F) range, ideal for L. pneumophila growth.

Water Sampling Protocol. Before starting decontamination, collect an adequate number of

water samples in sterile containers. These samples should be cultured to determine the

degree of contamination and the subtype of L. pneumophila before treatment. Collect at

least three water samples (200 milliliters to 1 liter volume). Include water from the

incoming make-up water supply, water from the basin of the unit most distant from the

make-up water source, and recirculated water from the HVAC system at its point of

return to the unit.

Clean-up Procedure.

1. Clean and disinfect the entire cooling system including attached chillers and/or

storage tanks (sumps) following the"Wisconsin Protocol" Emergency Protocol, as follows:

"Shock" treat cooling tower water at 50 ppm free residual chlorine.

Add dispersant.

Maintain 10 ppm chlorine for 24 hours.

Drain system.

Refill and repeat steps a through d.

Inspect system for visual evidence of biofilm. If found, repeat steps a through d.

Perform mechanical cleaning (cooling tower design may require modified

procedures).

Refill system, bring chlorine to 10 ppm, and circulate for one hour.

Flush system.

Refill with clean water in accordance with an effective water treatment program.

The unit is now ready to be returned to service.

2. Identify and eliminate all water leaks into the cooling water system.

3. After completing step 1, sample the cooling water for analysis of CFU of L.

pneumophila. The unit may be put into service provided the medical monitoring program

has been implemented. If sample culture results indicate detectable levels of L.

pneumophila, repeat chlorination and resample the water.

4. Once the nondetectable level for L. pneumophila has been achieved, institute

maintenance as outlined in the Wisconsin Protocol to ensure continued safe and proper

operation, as follows:

Inspect equipment monthly.

Drain and clean quarterly.

Treat circulating water for control of microorganisms, scale, and corrosion. This

should include systematic use of biocides and rust inhibitors, preferably supplied by

continuous feed, and monthly microbiologic analysis to ensure control of bacteria.

Document operation and maintenance in a log or maintenance records book.

5. Test cooling-system water at the following intervals to verify that there is no

significant growth of Legionella, as follows:

Test weekly for the first month after return to operation.

Test every two weeks for the next two months.

Test monthly for the next three months.

6. The standard for Legionella concentration throughout the six months of monitoring is

fewer than 10 CFU per milliliter (based on PathCon guidelines). If no water samples

exceed this level, monitoring may be suspended. The maintenance program must continue

indefinitely.

If any sample contains 10 or more CFU Legionella per milliliter, take immediate steps to

reduce levels to acceptable limits. These steps may include increased frequency of

application or concentration of biocides, pH adjustment, additional "shock" treatments, or

any other action that reduces Legionella levels. Take new water samples and begin the

testing schedule again. Make the results of all water monitoring tests available to building

occupants.

DOMESTIC WATER SYSTEMS.

Domestic water systems are designed to provide heated water for washing, cleaning,

consumption, etc. A large building may have multiple independent systems. These

systems usually include a boiler or heater, a recirculating piping system, and pipes

terminating in taps and fixtures. Operating temperatures vary depending on system

design, energy conservation programs, and intended use of the water. It is recommended

that water heaters be kept at a minimum of 60°C (140°F) and all water be delivered at

each outlet at a minimum of 50°C (122°F).

It is essential to identify all parts of the domestic water systems where water may

stagnate (e.g., "dead legs" or laterals that have been capped off, storage tanks that

have "dead zones" or are not frequently used). For treatment to be effective, the

stagnant zones must be removed from the system. Rubber and plastic gaskets in the

plumbing system may also serve as a Legionella growth medium. Eliminate or minimize use

of these materials and substitute materials not conducive to Legionella growth. It is also

important to identify and test the integrity of all backflow preventers to assure protection

of domestic water from cross-contamination with process water through a building

code-approved method.

WATER SAMPLING PROTOCOL.

Collect water samples before beginning treatment to determine potential contamination.

Draw 200 milliliters to 1 liter of water from the draw-off valve of all water heaters into a

sterile container. Check the temperature of the water in these units to determine if it is

significantly lower than the set temperature. Sample a representative number of domestic

hot-water faucets or outlets. It is important not to flush the faucet before taking a

sample because the end section of the water system may be a source of contamination.

Collect a 200 milliliter to 1 liter "preflush sample" of the first hot water drawn from the

outlet. Allow the water to run and measure the temperature, and then collect a second,

"postflush" sample when the water temperature is constant. Submit the water samples to

a laboratory qualified to measure CFU of Legionella per milliliter of water.

Use the clean-up procedure below to treat all hot-water systems that have either been

tested and found to contain detectable levels of Legionella or have been assumed to be

contaminated.

1. Disinfect the system using any effective chemical, thermal, or other treatment

method. For example:

Pasteurize the hot water system by heating the water to at least 70°C (158°F) and

maintain this temperature for a minimum of 24 hours. While maintaining the

temperature at 70°C (158°F), continuously flush each faucet on the system with

hot water for 20 minutes.

Use an accepted chemical disinfectant such as chlorine or an acceptable biocide

treatment to clean the system. Thoroughly flush the system after treatment to

remove all traces of the corrosive and possibly toxic chem