Legislation on the Topic: “Prevention of Legionnaires’ Disease”

Circular ID: Δ1δ/οικ. 60055/2-8-2018

This circular outlines the risk assessment, sampling, and preventive measures for Legionnaires’ disease, following the latest guidelines from the European Working Group for Legionella Infections (EWGLI).

Key Points:

A. RISK ASSESSMENT

To assess the risk of exposure to Legionella, a thorough investigation is necessary, which should include:

1. All Water Systems: All water systems, including supply sources and internal networks, should be inspected.
2. Preventive Measures: Implement all necessary preventive measures as required.

Points to consider during risk assessment:

1. Source of Water Supply: Determine if it comes from a municipal supply or other sources.
2. Potential Contamination Points: Identify any potential contamination sources within the facility before water reaches storage tanks, cooling towers, or other systems that use water.
3. Operational Characteristics: Collect data on the operational characteristics of the water supply systems from the facility manager.
4. Unusual Conditions: Identify any unusual but predictable conditions, such as leaks.
5. Air Intake Locations: Ensure air intake points are not located near cooling tower exhausts.

Components of a Water System:

• Includes all installations and equipment, such as pipes, pumps, tanks, valves, showers, heat exchangers, fire extinguishing tanks, and coolers.
• Periodically used sections, such as hotel areas closed in winter, must be included.
• Complex buildings or installations require checking all water systems.

Risk Assessment Report Should Include:

1. Diagram and Description: A layout diagram and description of water supply and air conditioning installations, including temporarily inactive parts.
2. Operational Description: Details on maintenance frequency, water temperature, chlorine or other disinfectant concentrations, preventive measures applied, and control measures frequency and methods.
3. Recommended Preventive Measures: List of recommended preventive measures.
4. Recommended Checks: List of checks to ensure minimal risk of Legionella exposure and their frequency.

B. SAMPLING

Sampling Points:

• Should represent the entire system.
• System inspection is crucial before selecting sampling points.

Cold and Hot Water Sampling:

1. Incoming Cold Water: Sample the incoming cold water to the facility.
2. Hot Water: Sample hot water leaving the heating tank or boiler.
3. Recycled Hot Water: Sample recycled hot water returning to the boiler.
4. Proximal Hot Water Outlets: Sample from the nearest tap or shower of hot water entry point to the facility.
5. Remote Areas: Sample from the most remote parts of the distribution system.
6. Affected Rooms: Sample from the room where the infected individual stayed.
7. Representative Rooms: Sample from rooms on different floors representing various branches of the system.

Sampling Instructions:

• Collect 1 liter of water in a sterile glass container with sufficient sodium thiosulfate to neutralize any chlorine or other disinfectant.
• If glass containers are unavailable, use pre-rinsed plastic containers.
• Measure water temperature during sampling with a thermometer placed in the middle of the water column.

Hot Water Sampling:

• Collect samples from the boiler: escape valves of hot water pipes, return pipes, and cold water pipes for heating.
• Sample from accessible drainage valves of storage tanks, if available.
• Collect immediate samples from taps upon opening (representing outlet flora).
• Collect second samples after letting the water run for at least 60 seconds (representative of system water).
• Take swab samples from shower interiors and handles with sterile cotton swabs.

Cold Water Sampling:

• Collect immediate and flow samples as for hot water.
• If water temperature is <20°C, reduce the number of samples.

Sampling from Storage Tanks:

• Collect samples directly from the tanks.

Cooling Towers:

• Collect samples from the water returning to the tower and from the tower basin.

Swimming Pools and Spas:

• Collect 1,000 ml of water from the pool, filter, and pressure balancing tank.

Humidifiers:

• Collect 200 ml samples directly from the unit.

Fountains:

• Collect at least one liter of water samples.

Sample Transport to Laboratory:

• Store samples at ambient temperature, protected from light, and transport to the laboratory as soon as possible, preferably within 48 hours. Do not freeze samples.

C. PREVENTIVE MEASURES

Immediate Measures:

• Based on risk assessment results and epidemiological data, implement preventive measures such as disinfecting potential sources with chlorine, cleaning tanks, and increasing hot water circulation temperatures if below 50°C.

Long-term Measures:

• Apply appropriate Legionella control measures for each system based on risk assessment and epidemiological data:
  • Oxidizing Disinfectants: Hypochlorous or hypobromous acid.
  • Non-oxidizing Disinfectants: Ionization, hydrogen peroxide, and silver solutions, ultraviolet radiation.

Hot Water Systems:

• Periodically perform thermal shock (70-80°C), maintain temperatures between 55-60°C.
• Use oxidizing disinfectants like chlorination, hyperchlorination, and alternatives like chlorine dioxide, monochloramine.
• Non-oxidizing disinfectants: ionization, hydrogen peroxide and silver solution, ultraviolet radiation.

Cold Water Systems:

• Use oxidizing disinfectants: chlorine, monochloramine, chlorine dioxide, usually at 0.5 mg/l concentration.

Swimming Pools and Spas:

• Continuous chlorination with chlorine at 1-2 mg/l or bromine at 2-3 mg/l, checked multiple times daily.
• Replace at least half of the water daily.

For more detailed information and guidelines, refer to the full text of the circular: Δ1δ/οικ. 60055/2-8-2018 εγκύκλιος με θέμα: «Πρόληψη της νόσου των λεγεωναρίων».