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Legionella. What is it and how do we treat it?. Legionella – What is it?. Type of bacteria found in bodies of water At least 39 species have been identified More than 60 serogroups have been identified Some serogroups have several subtypes. Legionella Pneumophila.
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Legionella. What is it and how do we treat it?
Legionella – What is it? • Type of bacteria found in bodies of water • At least 39 species have been identified • More than 60 serogroups have been identified • Some serogroups have several subtypes
Legionella Pneumophila • Most common species of all • 15 serogroups • Serogroup 1 has at least 50 subtypes • Causes 85 to 90 percent of all cases
What is Legionaires’ Disease? • A multisystem illness with a deadly type of pneumonia • Named by the press to identify the unknown bacterium
Legionaires’ Disease • First identified – Bellevue-Stratford Hotel – Philadelphia, July of 1976 • Illness struck 221 people • 72 who did not attend the convention • 34 died
Did you know? • 2.4 million cases of pneumonia each year in the U.S. • 10,000 to 100,000 are cases of Legionaires’ disease • Only 1,000 to 3,000 are reported to CDC
Legionaires’ Disease • Cases go undetected due to lack of testing • Other cases missed because test procedures are not sensitive enough • Deaths from undetected cases classified as pneumonia with an unknown cause
Legionaires’ Disease • Most cases occur one or two cases at a time and not an outbreak • Sporadic cases generally not reported to the public • Overall opinion is that the problem is not that great
Legionaires’ Disease • Considered an environmental disease – water to people. Not communicable. • Transmission occurs when airborne water droplets containing Legionella are inhaled
The Risk of Infection is Based on Two Key Factors • The number of bacteria reaching the body • The resistance of the individual
Legionella – Where does it come from? • Poorly treated water • Poorly designed plumbing systems • Poorly treated plumbing systems
Primary Sources of Legionellae Bacteria • Domestic Hot Water Systems • Cooling Towers • Evaporative Condensers • Respiratory Care Equipment • Showers
Primary Sources of Legionellae Bacteria • Faucets • Whirlpool Baths • Humidifiers • Fountains • Grocery Store Produce Mister
Legionella – Where does it live? • Bacterial amplifiers • Biofilm within plumbing systems
Thermo- meter Heated Water Safety Relief Valve Temperature signal is “fed back” through capillary tube Temperature Reg Valve Liquid or Gas Filled Bulb P Storage Tank Steam Supply Recirculatin Pump V.B. F&T Trap Make Up Water Condensate Return Recirculated Water Storage Tank Feed-Back System
Legionellae and Temperature • Below 68°F legionellae can survive but are dormant • Legionellae growth range (68°F – 122°F) • Ideal growth range (95°F – 115°F) • Above 122°F legionellae can survive but do not multiply • At 131°F legionellae die within 5 to 6 hours • At 140°F legionellae die within 32 minutes • At 151°F legionellae die within 2 minutes • Disinfection range (158°F - 176°F)
Preventive Measures • Maintain mechanical and plumbing systems for the control of Legionella • If you are high risk for Legionella consider more costly measures to fix your systems and reduce the risks • Document all preventive measures to show you took responsible action
Environmental Samplings • CDC does not recommend regular water sampling • Negative results may create a false sense of security and positive results a false alarm • Sampling results, though sometime inconclusive, provide lifesaving information
Samplings – Yes or No? • Weigh value of information provided against the cost • Weigh the risk of misleading sampling against the risk of not sampling • Consider risk management • DO NOT use as a substitute for preventive measures
Methods of System Treatment • Superheat and Flush (thermal) • Feed-Forward Instantaneous Water Heaters (thermal) • Hyperchlorination (biocide) • Ultra Violet Rays (biocide) • Ozone (biocide) • Chlorine Dioxide (biocide) • Copper/Silver Ionization (biocide)
Superheat & Flush Positives • Inexpensive • Proven effective irrespective of water quality • Non aggressive to pipe work and fittings • Non toxic/consumable • No professionally qualified personnel required to administer treatment
Superheat & Flush Negatives • Potential scald risk • Non-effective unless sterilization temperature is achieved (biofilm) • Dead-legs may not permit adequate flushing
Temperature in F° 111.2 116.6 118.4 122.0 131.0 140.0 149.0 158.0 Time for 1st degree burn 5 hours 35 minutes 10 minutes 1 minute 5 seconds 2 seconds 1 second ------ Temperature/Time Burn Chart
What types of Water Heaters are on the market today? • Feed-Back Units: Operate on a differential of water TEMPERATURE • Feed-Forward Units: Operate on a differential of water PRESSURE
Thermo- meter Heated Water Safety Relief Valve Temperature signal is “fed back” through capillary tube Temperature Reg Valve Liquid or Gas Filled Bulb P Storage Tank Steam Supply Recirculatin Pump V.B. F&T Trap Make Up Water Condensate Return Recirculated Water Storage Tank Feed-Back System
Blended Water Out @ P2 Mixing Chamber “Over-heated” Water from tube bundle Valve #3 P1 P2 Valve #2 Supply Water In @ P1 Valve #1 Tube Bundle Feed-Forward Instantaneous Water HeaterControl Valve Schematic
Feed-Forward Instantaneous Water Heater Positives • Sterilizes water in the heat exchanger as a function of making hot water
Blended Water Out @ P2 Mixing Chamber “Over-heated” Water from tube bundle Valve #3 P1 P2 Valve #2 Supply Water In @ P1 Valve #1 Tube Bundle Feed-Forward Instantaneous Water HeaterControl Valve Schematic
Feed-Forward Instantaneous Water Heater Positives • Sterilizes water in the heat exchanger as a function of making hot water • Non aggressive to pipe work and fittings • Non toxic/consumable • No scald risk
Feed-Forward Instantaneous Water Heater Negatives • Water which bypasses the heat exchanger is not sanitized • Does not kill bacteria in the system biofilm
Hyperchlorination Positives • Inexpensive • Effectively kills bacteria in the water
Hyperchlorination Negatives • Hazardous material which requires trained operators in order to handle • The chemical is a carcinogen • Aggressive to pipe work and fittings • Does not kill bacteria in the biofilm
Ultra Violet Positives • Harmless and non-toxic • Effectively kills bacteria in the water
Ultra Violet Negatives • Expensive • Only effective at point of treatment • High maintenance cost – lamps wear out and are fragile and need replacement • Micro organisms can become resistant and repair UV damage • Does not kill the bacteria in the biofilm
Ozone Positives • Effectively kills bacteria in the water
Ozone Negatives • Difficult to maintain effective levels of ozone in the system – decomposes into water • High ozone levels may damage pipe • Not tested in facilities – its use would be pioneering • Does not kill the bacteria in the biofilm
Chlorine Dioxide Positives • Effectively kills bacteria in the water • Early indications show potential of killing bacteria in the biofilm as well as removal of biofilm
Chlorine Dioxide Negatives • Expensive • Concentration levels required often exceed health standards – health & safety issues • Aggressive to copper piping • Needs special storage – hazardous material • Chemical (Potassium, Chlorate and Hydrochloric Acid) is unstable – may explode • Professionally qualified personnel required
Copper/Silver Ionization Positives • Use of sacrificial anodes produce ions that kill Legionellae bacterial in the water • Ions also kill bacteria in the biofilm
Copper/Silver Ionization Negatives • Expensive • Constant monitoring of ion levels • Sacrificial anodes need regular replacement • Ion levels can become toxic if they accumulate • Professionally qualified personnel required