Transcript Legionella Bacteria in Building Water Systems (OHAO2015)DW

Legionella Bacteria in Building
Water Systems: What do we
currently know and what is
upcoming?
Donald Weekes, CIH, CSP, FAIHA
Partner
Agenda
 Background
 Current Regulations and
Guidelines
 Current Practices
 Missing Links
Legionnaires Disease (1976)
Legionnaire’s Disease is Increasing
Legionellosis Incidence Rates in Canada
(1991- 2013)
Source: Public Health Agency of Canada. http://dsol-smed.phac-aspc.gc.ca/dsol-smed/ndis/charts.php?c=yl
Question on Legionella
 What is the most common of these locations where
Legionnaire’s Disease occurs?
 Nursing homes and health care facilities
 Office buildings
 Industrial plants
 Schools and universities
The Cause: Legionella
Bacteria
Legionella Bacteria
 Bacteria mostly found in stagnant water and soil.
 The temperature range for the bacteria is between 25-42 o C.
 Can survive at a maximum RH of 65% in aerosol form.
 Survives under a wide range of dissolved oxygen levels.
 The presence of biofilm and organic matter amplifies the
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Legionella bacterial growth.
Legionella spreads through mists, vapours, and droplets.
Mild febrile illness (Pontiac fever) to a potentially fatal form of
pneumonia (Legionnaires’ disease).
Susceptible population (age, illness, smoking).
Mortality rate is estimated 10-15% (PHC).
Possible Sources of Legionella Bacteria
 Incoming Water
 Cooling towers
 Humidifiers
 Showers
 Ice Machines
 Fountains
 Faucets
 Pools, spas, etc.
Proliferation of Legionella
 Biofilm facilitates nutrient and gaseous
exchanges for rapid colonization
 Protects bacteria and microorganisms
from biocides and increased
temperatures
 Biofilm can be generated on pipes, distal
sites, and stagnant areas
 Research shows that bacteria associated
biofilms can be more resistant to
biocides than freely suspended bacteria
 According to the U.S. EPA (1999)
Legionella bacteria can effectively out
compete other bacteria in the presence
of biofilm (under ideal conditions)
 Biofilm facilitates nutrient
and gaseous exchanges for
rapid colonization.
 Protects bacteria and
microorganisms from
biocides and increased
temperatures.
 Biofilm can be generated on
pipes, distal sites, and
stagnant areas.
 Research shows that bacteria
associated biofilms can be
more resistant to biocides
than freely suspended
bacteria.
Source: http://www.commerce.wa.gov.au/sites/default/files/atoms/files/legionnairescode.pdf
Incidence
 U.S. legionellosis cases reported annually increased 217%, from 1,110 in
2000 to 3,522 in 2009.
CDC. Increasing incidence of Legionellosis in the United States, 2000-2009. MMWR2011;60:1083-1086.
 UK – Average of 300 – 400 cases per year (2004 -2013)
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/363380/LD_annual_report__2013_PHE_2014392.pdf
 ECDC – 5,856 cases in 30 countries in 2012. Stable levels (2008-2011).
European Centre for Disease Prevention and Control. Annual epidemiological report 2014 – Respiratory tract infections.
Stockholm: ECDC; 2014
 Canada
 < 100 cases per year.
http://www.phac-aspc.gc.ca/id-mi/legionella-eng.php
 Average incidence in Ontario increased 39.2% (2009-2013).
http://www.publichealthontario.ca/en/eRepository/Epidemiology_Legionellosis_Ontario_Report_2013.pdf
 Incidence is likely underreported.
 Increased and better diagnostic and surveillance programs cannot explain
the entirety of the increased incidence of legionellosis.
Legionella in the News
Recent outbreaks (2014-16)
 Flint, Michigan:
 City changed its water source from Lake Huron to the Flint
River in April, 2014 and back in October
 Since switchover, 90 people have fallen ill due to
Legionnaire’s disease
 Of those infected, 10 people have died
 Investigation ongoing, source unknown (corrosion?)
Legionella Documents
 MD 5161-2013: Control of Legionella in Mechanical Systems (Public Works
and Government Services Canada).
 ANSI/ASHRAE Standard 188-2015, Legionellosis: Risk Management for
Building Water Systems.
Règlement sur l’entretien d’une
installation de tour de refroidissement à
l'eau
Intent of Legionella Documents
 Provide a preventative frame work to reduce Legionella
contamination in building systems.
 Standardize a process for all stakeholders involved in the
design, construction, and operation and maintenance of a
building.
 Provides requirements for:
 Design;
 Operation;
 Maintenance; and
 Testing
ASHRAE LEGIONELLA STANDARD
 Standard 188 - 2015
 Building Code format
 Focussed on the design,
maintenance & operation
of building water systems
 Development of water
management program
 Monitoring (sampling)
part of Program
AIHA LEGIONELLA GUIDELINE
 Recognition, evaluation &
control of Legionella
Bacteria
 Focus on risk assessment
rather than risk
management
 Environmental monitoring
to determine the
effectiveness of controls
 NOT air sampling
PWGSC LEGIONELLA DIRECTIVE
 Applies to federal buildings
(new & existing)
 Focus on design,
maintenance, operation &
testing of building water
systems
 Minimum requirements that
must form part of a facility’s
Legionella Bacteria Control
Management Program
(LBCMP).
USEPA – DRAFT LEGIONELLA
DOCUMENT
 Scientific Literature
Review
 Open for comments
through November 23rd,
2015
 Focus on research papers
about methods of
disinfection
 Less than ‘positive’ about
environmental sampling
Cooling Tower Design (MD-15161)
 Relevant for new facilities and major
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upgrades.
Outlines minimum separation distance
from air intakes and various critical
receptors.
Avoid housing cooling towers near sources
of organic matter.
Equip cooling towers with highperformance drift eliminators.
Factors that should be considered:
• Prevailing wind directions;
• Location of enclosure and screens;
• Heights of surrounding structures;
• Prevention of direct sunlight on wetted
surfaces;
• Providing easy access for cleaning and
disinfection.
O&M and Testing
 Conduct a full risk assessment of:
Cold water systems.
 Hot water systems.
Use of temperature controls:
 Hot water distributed at 60°C or higher.
 Cold water distributed below 20°C .
Remove dead legs/ dead ends in pipes, and flush out other
pipes infrequently.
Sampling - Location and frequency of testing is dependent
on risk assessment.
To further control Legionella, the use of biocides and
disinfection treatments can be used.
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System Risk Assessment
 From all information gathered during site visit, a
level of risk is assigned to each component of each
system based on hazard characteristics.
 Low/Medium/High
Humidifier example:
System Type
Hazard Characteristics
Risk
Level
Humidifiers
Direct steam, IR, or gas humidifier
Low
Any other type of humidifier
High
Water stagnation exists
Medium
Schedule of O&M for Steam
Humidifiers
Frequency
Upon system start up
Every 3 months
Every 3 months
If necessary*
Action
• Visually inspect the humidifiers for signs of
microbial growth, sediment or stagnant water.
• Clean and drain these systems following
manufacturer recommendations.
• Visually inspect humidifiers for signs of
microbial growth, sediment or stagnant water
every 3 months for steam systems.
• Clean and drain these systems following
manufacturer recommendations.
• Perform dip-slide test, when system is in
operation and stagnant water is present*.
Refer to Testing Protocol for HVAC
Systems.
• If disinfection is required from test results,
refer to the Disinfection Procedure for HVAC
Systems.
But…
 Four different buildings in
Ottawa in the summer of
2015 with at least one
Legionella case
 Place du Centre
 Place du Portage III
 Jean Edmonds Tower
 30 Victoria
So why?
Testing
 To test or to not test.
 Methodology and
techniques – Dipslide vs.
Culture.
 Interpretation of results.
 Interpretation of
exposures.
 Field Test Kits.
 Methods that are selective for
Legionella bacteria.
 Conventional culture methods
versus PCR.
 Culture is Gold Standard.
www.emlab.com
wwwnc.cdc.com
Interpretation of Metrics
 Elevated percent positivity (30%) of Legionella in hospital
domestic water systems has been suggested as a metric for
assessing the risk of health care acquired Legionnaires’ disease
(LD).
 The proposed 30% positivity metric has 59% sensitivity and
74% specificity (i.e., a 41% false-negative rate and a 26% falsepositive rate).
 16 peer-reviewed articles and 6 government guidance
documents that referenced the 30% positivity metric as a risk
assessment tool.
Assessing risk of health care-acquired Legionnaires’
disease from environmental sampling: The limits of
using a strict percent positivity approach
O&M
 Water treatment
 cooling towers.
 humidification systems.
 Domestic hot water
systems.
 Terminal equipment
 Shower heads
 Fire suppressant
 Spigots
 Disinfection methods –
thermal and chemical
 validation of methods
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pH
Chlorine
Biofilm inhibitor
Temperature
Disinfection
 Muraca et al. (1987) conducted a comparative assessment between several
disinfectants for killing Legionella pneumophila in a controlled plumbing
system. The results of the research found:
Most disinfectants
don’t provide for a
total kill of bacteria.
Disinfection
 Legionella
diversity
was
reduced,
but
pathogenic
Legionella
species
(Legionella
pneumophila and Legionella anisa) remained after the heat
shock and chemical treatments, respectively.
 The biofilm was not removed, and the bacterial community
structure was transitorily affected by the treatments.
 Moreover, several amoebae were detected in the biofilm
before treatments (Thecamoebae sp., Vannella sp.,
and
Hartmanella
vermiformis).
However,
known Legionella eukaryotic hosts (Alveolata) dominated the
eukaryal species after the second heat shock treatment and
the chemical treatment.
Failures of Disinfection
 NY Times Headline – Oct. 1,
2015: ‘Legionnaires’ Bacteria
Regrew in Bronx Cooling
Towers That Were Disinfected’
 ‘The 15 water-cooling towers
that were found to be
contaminated this week amid a
new cluster of Legionnaires’
disease cases had been
disinfected less than two
months ago, New York City
officials said on Thursday,
raising questions about how
successful the city can be in
containing the disease.’
Design of Systems
 Non potable water storage for
flushing and watering (spray)
 Organic Deposit;
 Lack of Agitation and Access.
 Green wall
 Used as part of HVAC;
 Non-chlorinated treatment;
 Recirculating Water.
 Smaller water heaters
 no control on temperature and
usage.
Blog.sciencenet.cn
A Practitioner’s Hopes and
Dreams
 More standardized methods
for inspection, O&M,
disinfection, etc.
 Possible regulation to help
implementation of control
plan.
 Critical Design.
www.id-london.com
 Energy efficiency vs. O&M
 More research on the ecology
and the growth factors, the
effectiveness of chemical
treatment, on the testing.
 Etc.
bcmates.com
www.lookfordiagnostic.com
Thanks to:
 Staff at InAIR Environmental Ltd. for insight, review and
support
 Lan Chi Nguyen Weekes, P.Eng.
 Scott Lessard
 Momin Malik, EIT
 Mark St-Pierre
Thank you!
Questions?