Session 8: Risk Assessments and Water Systems Facilitator notes: Legionnaires’ disease: Risk assessment, outbreak investigation and control Session 8: Risk Assessments and Water Systems ECDC, 2011

What is Risk Assessment? A method of identifying hazards and risks in an activity, workplace or other setting It generally involves control measures The control measures invariably are there to protect employees, the general public and other people Prepared by competent people, often written and must be reviewed

What is Risk Assessment - for the control of Legionella in water systems? A method of identifying hazards – such as the biological hazard of Legionella pneumophila A system for assessing risks of these biological hazards – with due consideration of the environmental exposures and the risk of disease Involves identifying control measures Prepared by competent people, often written and must be reviewed – often referred to as; a water safety plan

Environmental Exposure and Disease No established dose-response relationship for Legionella infections Transmission may occur through inhalation, aspiration or directly from contaminated water Other sources of Legionella bacteria have been identified/linked to cases/cluster and outbreaks Clinical microbiology is often insufficient to link to the source and environmental samples Do we miss cases?

Targets for Public Health What target should we set for cases of Legionnaires disease? What are the risks within water/aerosols? What is safe? What is acceptable? Who should set the targets - for levels in water systems?

Environmental Targets - the Issues Clinical/culture based methods are based on the isolation of Legionella pneumophila Sg1 Limitations of Environmental samples – for verification of control and during outbreaks/incidents Susceptibility to infection varies Risks linked to particular aerosols varies Develop a plan for management

Legionella Management Planning Water safety plans/risk assessment plans Assessment – risk based, prioritising hazards and risks in the system Premises specific Monitoring – Management – Communication - Review

Who is in the team? Assemble a team And how? Document what? Document the system And risks! What hazards? Assess hazards How do we assess? Assess the system What are the controls? Identify controls Monitor controls Validate controls What is the support system? Develop support system Prepare management procedures Documentation and Communication Record, audit and review

Assembling the team Document the system Individuals with an understanding of the water systems – it’s design and operation an understanding of the ecological factors that encourage Legionella growth A multidisciplinary team will be required for complex settings External expertise may be required to support Document the system List the water systems that may be present

Identify possible control points and controls Identifying layout and design - schematics Document the system Assess hazards Flow charts – assist in the understanding characteristics of the water system Assess the system Identify pathways – by which legionellae can be transferred to consumers Identify risk points in the water system Identify possible control points and controls

Consider seasonal variations Employ expert assistance Assess all of the hazards Assess the system Hot roofs spaces/roof voids Over sized water storage tanks Poorly insulated pipes Consider seasonal variations Employ expert assistance

Control – temperature of water Controls and control points Control – design of system, including low flow areas Control – potential media /surfaces for growth of the organism Control – nutrients eg organic matter and sediments Control – temperature of water Premises specific assessments and controls All systems, areas, outlets, sources of hazard – and potential risk

Control – using temperature Other control mechanisms/systems ………

Controls – advantages and disadvantages of control methods in water systems Cold supply Hot hold Hot flush Hypochlorite Monochloramine Chlorine dioxide

Controls – advantages and disadvantages of control methods in water systems H-Peroxide Cu Ag oxidation U/V Filtration Filters Hot and heat Biocides

Who is in the team? Assemble a team And how? Document what? Document the system And risks! What hazards? Assess hazards How do we assess? Assess the system What are the controls? Identify controls Monitor controls Validate controls What is the support system? Develop support system Prepare management procedures Documentation and Communication Record, audit and review

Controls – identify sampling points, for monitoring and verification of control

Controls – identify sampling points, for monitoring and verification of control

Management procedures Support system Training – and competencies Recording and gathering reflective data Developing verification protocols Management procedures Actions – in response to failures Actions – in response to incidents Role and responsibilities identified Document the system Communication

Communication Identify personnel involved in; Developing and identifying control measures Maintaining controls Managing the water safety plan Clear statements of responsibilities – to ensure cooperation and robust actions/response

Communication Targets/controls and monitoring points List of required maintenance records Verification data – sampling and results Routine maintenance – action list Description and assessment of the water system – including a current schematic Training records etc Procedures – for normal operation and incidents

Risk Assessment and Water Safety Plans Not about the safety of staff – health and safety But - the control of legionella in the water system

Questions

Facilitator notes: Acknowledgements The creation of this training material was commissioned in 2010 by ECDC to Health Protection Agency (UK) and the University of Chester (UK) with the direct involvement of Louise Brown, Janice Gidman, Emma Gilgunn-Jones, Ian Hall (on behalf of the ECDC Legionnaires Disease Outbreak Toolbox Development Group), Tim Harrison, Rob Johnston, Carol Joseph, Sandra Lai, John Lee, Falguni Naik, Nick Phin, Michelle Rivett, and Susanne Surman-Lee. The revision and update of this training material was commissioned in 2017 by ECDC to Transmissible (NL) with the direct involvement of Arnold Bosman and Kassiani Mellou.