LEGIONNAIRES’

Dr. Janet Stout Thomas Bigley Dain Hansen

Janet E. Stout, PhD
President, Director, Special Pathogens Laboratory
Research Associate Professor, University of Pittsburgh
LEGIONNAIRES’
DISEASE RISK AFTER
COVID-19 SHUTDOWN

My Affiliations – Two Hats
• President of Special Pathogens
Laboratory, a laboratory and
consulting firm specializing in
Legionella detection and control
• Research Associate Professor in
the Dept. of Civil & Environmental
Engineering at the University of
Pittsburgh

© Special Pathogens Laboratory
Keep Going?
COVID-19

Making the Best of COVID-19!

Safe Reopening: Managing Risk
• Four Steps
 Include low flow conditions and changes
in occupancy in your water safety and
management plan
 Test for Legionella before and after
reopening
 Have a disinfection plan
 Document, document, document!

WHY DO MICROBES
LIKE A SHUTDOWN?
What Have We Learned?

Who’s at the Party?
• Pseudomonas
• Acinetobacter
• Burkholderia
• Stenotrophomonas
• Nontuberculosis mycobacteria
• Legionella

WHAT HAPPENS TO
WATER QUALITY?
What's Flow Got to Do With It?

Stagnant or Standing Water
• Disinfectant residual decreases
• Hot water isn’t recirculating, so
temperature drops.
• Cold water isn’t flowing and warms up
in the pipes of unoccupied floors and
rooms.
• Legionella growth range is >77 to
108°F (>25 to 42°C).

Stagnant or Standing Water
• Increase time water is in the pipes
(water age) degrades water quality.
• Legionella bacteria grow well in the
company of other microbes (synergy).
 Rapidly growing bacteria provide
Legionella with nutrients

No Flow, They Grow

Closer Look
• This experiment
shows that bacteria
will grow given a
nutrient source and
stagnant water.
• What’s in your
stagnant pipes?

Their Growth Helps Legionella
Legionella
Other
Bacteria

One Microbe Helps Another
• Legionella bacteria grow well in the
company of other microbes (synergy).
 Amoebae are close enough to
Legionella in a no flow condition to
engulf them
 Legionella isn’t destroyed, it turns the
table and grows inside the amoebae
until it bursts, spewing hundreds of
Legionella

Legionella Multiplies,
Hundreds Released
Courtesy Center for Biofilm Engineering, Montana State University

Other Changes in Water Quality

Re-pressurization Dislodges This
Cross section of 4-inch
pipe from hospital hot
water system
Got Brown Water?

Outbreaks and Changes
in Water Quality
• Association with Legionella growth
and spread, water quality disruption
and delayed occupancy first noted by
Mermel in 1995

Potable Water Quality Changes
Preceded Outbreaks

Mermel’s Recommendations
• Culture water system before, during
and after excavation or shut down
and re-pressurization of supply
• Cultures for Legionella should be
carried out, especially if the supply
services areas for
immunocompromised patients

Recommendations
• Persistent discoloration of potable
water should be reported to
maintenance personnel and infection
control

Preventing Legionnaires’ Disease
• Know risk when you see it. Don’t ignore it!
• Resources for water management and
shut down/start up procedures after
dormancy
 CTI GDL-159, ASHRAE (Standard and
Guideline), AWT, IAPMO, ASSE Standard
12000, etc.

Lots of Guidelines, Some Regulations

 ASHRAE Standard
188 & Risk
Management
a. Assessment
b. Water Safety
Plan
c. Risk mitigation
d. Decontamination/
disinfeciton
Preventing
Building-associated
Legionnaires’ disease

ASHRAE Guideline 12-2020
Publication May 1, 2020

Cooling Technology Institute
Guideline 159

What I Like About GDL-159
• Uses performance-based approach
• States that a microbial control
program is part of an effective water
management program to control
legionellosis

WHAT ABOUT
MICROBIAL CONTROL?
Shock Disinfection?

Flushing Is Not Disinfection
• Moving water through fixtures will
improve overall water quality and may
temporarily reduce Legionella in the
water from the outlet
• Legionella is within and throughout
the system
• Flushing alone will not eliminate the
risk of exposure

When to Consider Disinfection

Guideline Section 5.3.2
Supplemental Disinfection
• Facilities where hot and cold water
temperatures recommended for Legionella
control cannot be maintained reliably
throughout the entire potable building
water system
• Facilities where there is not a consistent,
measurable disinfectant residual at all hot
and cold water taps after about one minute
of flow

White Paper with Resources for You
• Operation of potable water systems during
low or no occupancy
• Reopening of buildings after COVID-19
• Water safety and management plan
response
• When and where to test for legionella
• Disinfection as a corrective action
• Documentation requirements

Preventing Building-associated
Legionnaires’ Disease

New ASSE Professional
Qualifications Standard
• Sets minimum criteria for the training
and certification of persons involved
in:
• Development, administration, and
execution of risk assessment and water
safety management programs
for Legionella in building water systems.

TESTING PLAYS AN
IMPORTANT ROLE IN
LEGIONELLA PREVENTION

Together We Can End
Legionnaires’ Disease!

THANK YOU!
STAY SAFE!
Dr. Janet E. Stout, President, Legionellologist
WWW.SPECIALPATHOGENSLAB.COM
INFO@SPECIALPATHOGENSLAB.COM

LEGIONNAIRES’

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