Environmental aspects of Legionnaires disease Dru Sahai, Environmental Science Specialist, PHO September 28, 2017 IPAC NEO conference
Objectives Describe how Legionella is transmitted Identify the common sources responsible for Legionnaires disease outbreaks Describe the factors that can leads to Legionella proliferation Outline how an outbreak source of Legionella is identified and remediated Explain the components of a water safety plan 2
Overview Legionella bacteria (G-) are opportunistic human pathogens Legionellosis Notifiable disease Pontiac fever is a milder self-limiting flu-like illness Legionnaires disease is generally a severe and potentially fatal form of pneumonia with a 2-14 day incubation Many different species ( 60) and distinct serogroup (70) Genus Legionella; Species pneumophila; Serogroup 1; Strain - Philadelphia 1 January 2010 to April 2014 L. pneumophila serogroup 1 represented 680 (93.8%) of all Legionella identified by PHOL (Peci et al.,2016) 3
Ecology Found in the natural environment including ground and surface water, moist soil (compost) Can exit in free floating form or within an amoeba host The amoeba (Acanthamoeba spp) provides nutrition and shelter Protects Legionella from heat and disinfectants Abdel-Nour et al. 2013 4
Ecology (cont.) Ruptured membrane Amoeba Free floating Legionella Amoeba can harbour up to 20 1500 pathogenic bacteria, such as L. pneumophila These may rupture, releasing the Legionella bacteria into the potable water system including tap and showers 5
Ecology (cont.) 70-80 C 60 C 55 C >50 C Temperature 20-50 C (25 42 C optimal growth conditions) Dies very quickly Survives several minutes Survives several hours Survive municipal water treatment Stagnation Scaling Corrosion Biofilm Piping Building pipe system Piping Replication within protozoa Reduced residual disinfectant Reduced temperature (<50 C) <20 C Survives but inactive Source: Abdel-Nour et al. 2013 with modifications Water surges vibration Piping Other species 6
Transmission Typically transmitted though inhalation by a susceptible host of minute aerosolized water droplets that contains Legionella (amoeba/legionella) in sufficient numbers High humidity increases viability Can occur by aspiration of Legionella into the lungs Humans have traditionally been considered a dead-end host for Legionella one probable case of person-to-person transmission has recently been reported. Several infections (Legionella longbeachae) have been linked to exposures to soil, potting soil and compost mode of transmission? 7
/aspiration Sources 9
Main sources Cooling towers Sink/ Potable water systems Electronic and manual faucets, showerheads and flexible hoses or connections to faucets Hydrotherapy Decorative fountains 10
Cooling towers Large community outbreaks almost always associated with a cooling tower where there is a high attack rate in a small area no common source is apparent 11
Evaporative cooling equipment (open system) Water film Source: Quebec outbreak Source: HSE Sump 12
Potable water system 49 C Hot water out Heat Exchangers Waste hot water Waste Cold water Cold water in Recirculated system 60 C 55 C <20 C Instantaneous water heaters Source: HSE Hot water out Cold water in 13
Potable hot and cold water systems (cont.) Thermal mixing valve The blended water downstream of TMVs may provide an environment in which Legionella can multiply, thus increasing the risks of exposure 14
Potable hot and cold water systems (cont.) Vs Where TMVs are fitted, they should be as close to the point of use as possible to minimize the storage of blended water 15
Non potable water systems Spas Decorative Fountains Water temperature (39-40 C) is ideal for Legionella (and other organisms) growth Disinfectant is rapidly lost because of high temperature and high bather load Equipped with jet and air blowers which can generate aerosols Persons using the spa are at most risk but a passerby also can be exposed Lack disinfectant lack maintenance protocol Underwater heating source (lighting) 16
Non potable water systems (cont.) Cooling mister Decorative fountain Cooling mister just outside hospital Numerous outbreaks have been associated with decorative fountain is hospitals 17
Some other potential sources Aerosol producing humidifiers Misting devices Birthing baths (aspiration) Powered dental equipment Ice machines aspiration Non-disposable medical equipment Nebulisers, ventilators and other respiratory therapy equipment that uses water for filling or cleaning Heater-cooler units Soil (usually potting) - L longbeachae Hospital dishwashers? 18
Healthcare risk Identified outbreaks generally are linked to large plumbing systems, such as those found in hotels or resorts, hospitals, long-term care facilities Old ( more likely to have corrosion and scaling) Complex Redundant pipework/dead legs/dead (blind) ends Long pipes (not insulated) Intermittent use Susceptible individuals Construction activity Energy conservation Encourages biofilm growth, reduces temperature and levels of disinfectant which leads to Legionella proliferation 19
Healthcare potable hot and cold water systems Legionella is very prevalent in healthcare water systems Numerous reports and outbreak investigations especially in hospital and long-term care facilities 12-85% of hospitals in US 55% of organ transplant hospital in the UK 40 % of hospitals in Queensland Australia Note: In facilities known to be colonized, disinfectants such as chlorine often used to maintain a residual 20
Environmental Testing Routine environmental testing for Legionella? Disputatious! Why not to sample (reactive approach)? Hard to interpret test results Limitations of sampling and analytical methods (false negative) Environmental Legionella counts alone cannot predict the likelihood of infection Difficult to establish action levels for initiation of corrective actions Negative testing can lead to false security and lax operation and maintenance practices Instead of sampling Assume the presence of Legionella Implement appropriate infection prevention and control measures (including actively screening for cases of Legionnaires disease) 21
Environmental Testing (cont.) 22
Environmental Testing (cont.) Why sample (proactive)? VHA, CDC and WHO: Despite difficulty interpreting test result routine testing is useful for confirming the effectiveness of control measures Almost all reviewed international guidelines recommended routine environmental testing for Legionella in HCF Especially where there is a vulnerable population Positive environmental sampling creates a high degree of suspicion and allows for active surveillance for cases 23
Environmental Testing (cont.) PHE, HSE, ASHRAE and the CDC Routine testing for Legionella be implemented on an individual system-by-system basis Based on an assessment of the risk According to the CDC, the circumstances when monitoring for Legionella may be appropriate include: Difficulty maintaining the building water systems within established control limits Having a prior history of legionnaires disease Being a healthcare facility that provides services to people who are at increased risk for Legionnaires disease 24
Environmental Testing (cont.) Despite limitations various agencies have adopted thresholds to trigger corrective actions (technical standard vs health based standard) UK - <100 cfu/l France/Netherland /Germany - <1000 cfu/l Log difference 25
Outbreaks Institutional Health care, hotels Community Around cooling towers, spas, grocery misters, outdoor fountains Workplace The Ministry of Labour should be informed about potential workplace exposure. Outbreaks (cluster) account for only 4% of cases LD is substantially underdiagnosed and under-reported Seasonal (June to November), peak - July Overall case fatality rate 5-30% (9% on average) In Ontario, the majority of cases (83.7%, 221/264) in 2013 were hospitalized 18.6% (41/221) were admitted to the ICU 10.2% (27/264) were fatal Important that all potential sources of Legionella are rendered safe ASAP especially in healthcare settings. 26
Outbreak investigation The laboratory investigation seeks evidence linking clinical cases to the environmental source of the outbreak (genetic match) Remediate The environmental investigation aims to Identify potential sampling sites by conducting an environmental assessment. Helps to identify the source through environmental sampling (ES) The case exposure investigation Collects clinical history and exposure details to identify a location. Focuses the environmental investigation 28
Diagnostic Tests UAT (urine antigen test) The most common laboratory test easy &quick If the patient has pneumonia and the test is positive, then the patient is considered to have Legionnaires' disease Designed to detect the most common cause of legionellosis L. pneumophila serogroup 1 Does not allow for linkage of human isolates with Legionella-positive environmental samples Patient with a negative urinary antigen result may have legionellosis caused by some other member of Legionella 29
Diagnostic Tests PCR (polymerase chain reaction) PCR may be performed on lower respiratory tract specimens Identifies L. pneumophila and detects all Legionella species (dead or live) All samples positive for Legionella by PCR are then cultured for the purpose of facilitating genetic typing (strain identification) Allows for linkage of human isolates with Legionella-positive environmental samples 30
Diagnostic Tests - Culture Isolation of Legionella from lower respiratory specimens is the gold standard Isolating Legionella from clinical specimens (culture) allows for genetic sequencing to identify the strain Provides link between environmental sources and human isolates by matching the strain Helps investigators identify the source so that remedial action can be taken to prevent additional cases 31
Reasons for no match Lag time between exposure to Legionella contaminated water and time of sampling conditions may have changed Didn't locate the source Shock disinfection before sampling occurred Not culturally viable Overloaded 32
Remediation & Emergency Measures (cont.) Once the environmental source of Legionella has been identified a remediation action plan should be implemented Not well versed in Legionella remediation and control - hire an environmental consultant The most common methods of remediating contaminated water systems is by thermal disinfection, chemical disinfection, or both Combining thermal and chemical disinfection is more effective than either alone 33
Remediation & Emergency Measures (cont.) Thermal Disinfection During thermal disinfection the water temperature should be increased and maintained at 71 77 C, for at least 30 minutes It is recommended that thermal disinfection be followed with chemical disinfection of the water system Chemical disinfection The most common of these chemicals used for chemical disinfection is chlorine. The level of chlorine should be dosed at 50 mg/l for an hour After disinfection is complete, the outlet should be flushed, reaching the ideal concentration of 0.5-1.0mg/L 34
Remediation & Emergency Measures (cont.) Chemical Disinfection The following chemicals are effective against Legionella Chlorine Chlorine dioxide Monochloramine Copper-silver ionization Ozone UV No residual effect Residual effect The plumbing components should be able to withstand the level of chemical disinfectant required 35
Remediation & Emergency Measures (cont.) Point-of-use Filters Commercially available membrane filters fitted to water outlets Microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) Effective in preventing Legionella from being released at the point of use Filters can be installed immediately and may be a better alternative than restricting showering and providing bottled water. Does not eliminate Legionella from the potable water system Follow the manufactures instructions on change out schedule 36
Post-Remediation Sampling After remediation, all previously contaminated sources should be resampled, to ensure that the recolonization of Legionella has not occurred NOTE: Biofilms can be difficult to remove even with thermal and chemical disinfection and they may serve as a reservoir for persistent Legionella contamination that can last for decades 37
Long term Prevention Most effective strategy for prevention of Legionnaires disease is through control of Legionella in water systems in buildings. Legionella water safety plan ANSI/ASHRAE Standard 188-2015 Legionellosis: Risk Management for Building Water Systems Best practices document which focuses on identifying hazardous conditions and applying control measures to interrupt Legionella growth and transmission. Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings: A Practical Guide to Implementing Industry Standard http://www.cdc.gov/legionella/downloads/toolkit.pdf 38
Long term Prevention (cont.) After an outbreak an institution may be persuaded to install a supplementary disinfection system especially in health care facilities Best available evidence indicates Copper-silver ionization and UVL are effective in reducing Legionella positivity Evidence is not robust (American journal of infection control 44.11 (2016) Outbreak has occurred despite copper-silver residual levels being mfg.'s recommendations Bédard et al. (2016) found L. pneumophila in the hot water system of a hospital from 85 percent of sampled taps despite copper treatment 39
The team should include someone who understands accreditation standards and someone with expertise in infection prevention Include all areas where hazardous conditions may contribute to Legionella growth and spread: Patient care areas (such as patient rooms and ICUs, dialysis, respiratory therapy, and hydrotherapy) Include all components and devices that can contribute to Legionella growth and spread. Think about all of the places where patients can be exposed to contaminated water. Don t forget about ice machines, heater-cooler units,* and respiratory therapy equipment. 1 Establish a water management program team 2 Describe the building water systems using text and flow diagrams 3 Identify areas where Legionella could grow and spread 5 Establish ways to intervene when control limits are not met 4 Decide where control measures should be applied and how to monitor them Think about: Areas where medical procedures may expose patients to water mists, such as hydrotherapy and respiratory therapy devices Areas where patients are more vulnerable to infection, such as bone marrow transplant units, oncology floors, or intensive care units *Devices that are commonly used during cardiac surgical procedures to warm and cool a patient s blood during cardiopulmonary bypass 6 Make sure the program is running as designed and is effective Continuous program review 7 Document and communicate all the activities 40
For More Information About This Presentation, Contact: Dru.sahai@oahpp.ca Public Health Ontario keeps Ontarians safe and healthy. Find out more at