Legionella. A detailed insight from our specialists. Overview Lifecycle How it manifests Strains and species Facts and statistics

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1 Legionella. A detailed insight from our specialists Overview Lifecycle How it manifests Strains and species Facts and statistics Laboratory process Sampling and analysis Illness and symptoms Interpreting results

They can grow at a range of temperatures, anywhere from 5 o C to 63 o C. However, optimal growth occurs between 25 o C and 40 o C.

2 John Searle. BSc (hons), MChemA, CChem, FIFST, MRSC Senior Microbiologist and advisor for AquaB Group LLP. What is Legionella? Legionella are aquatic organisms that are commonly found naturally in environmental water sources such as rivers, lakes and reservoirs, but are usually in low numbers; humans are accidental hosts. They can grow at a range of temperatures, anywhere from 5 o C to 63 o C. However, optimal growth occurs between 25 o C and 40 o C. The organisms do not appear to multiply below 20 C and will not survive above 60 C. They may, however remain dormant in cool water and multiply when water temperatures reach a suitable level. Legionella bacteria also require nutrients to multiply, and sources include commonly encountered organisms within the water system itself such as algae, amoebae and other bacteria. The presence of sediment, sludge, scale, rust and other material within the system, together with biofilms, are also thought to play an important role in harbouring and providing favourable conditions in which the legionella bacteria may grow. Life-cycle of Legionella Although free legionella may be readily detected in freshwater, L. pneumophila is not a free-living organism but a parasite of amoebae. Amoeba absorbs the legionella organism. Legionella then use the nutrients inside the amoeba to multiply. Once mature the amoeba cell bursts open to release hundreds of Legionella organisms. One species, Legionella micdadei has been discovered in highly acidic geothermal environments. They used their ameoba hosts to protect them from this harsh environment. Why should we be concerned about Legionella? Legionella is found in aquatic environments including hot and cold water systems, cooling towers, humidifiers and in other areas where stagnant water is present. It is classed as an opportunistic pathogen which means that in certain situations it is able to infect people and cause illness. Infection normally occurs when contaminated water forms aerosols which are then inhaled into the lungs. Such aerosols can be generated by turning on a tap or shower. The Health and Safety executive (HSE) and local authorities have mainly been concerned about mass out breaks of the disease which you have no doubt heard about. These out breaks were mainly centered on public buildings such as commercial buildings/offices with cooling towers and more importantly hospitals. Even during these times of NHS cut backs the service is spending significant amount of money to ensure that their water systems are not at risk from the Legionella organism. However, in the last year it has been publicised that Legionella can be found in calorifiers, pipework and header tanks of residential properties. To this end the code of Practice on the control of Legionella in water systems (also known as L8) (ACOP) had been revised to include residential properties. Legionella Not just for Hospitals and big buildings

3 All Landlords have a duty of care under Health and Safety law to ensure that the properties under their control are safe. As a provider you have responsibilities to ensure that the risk from exposure to legionella in your premises is properly controlled. Legal requirements are outlined in the ACOP Those responsible for the property will need to carry out risk assessments to ensure that the risk from Legionella is appropriately controlled and managed. Certain species of Legionella can cause mild to severe illness collectively known as Legionnaires disease or Legionellosis. This disease was first identified in 1976, following a large outbreak at an American legion convention in Philadelphia. 226 people were infected with 34 deaths. This maybe only the tip of the iceberg as many cases remain unreported and not diagnosed. NHS cutbacks have influenced many hospitals routines. There is currently no known vaccine for its prevention. There is no doubt that LEGIONELLOSIS is a potentially DEADLY threat if left unaddressed. Now being found present even in what is classed as low risk environments it now confirms previously expressed views and concerns. Much more data is being gathered as awareness grows. It is estimated that 2 in a 100 admitted pneumonia cases are Legionella related. What are the symptoms of Legionellosis? Legionellosis can cause two types of illness: 1. A severe form of pneumonia (Legionnaire s disease) often accompanied by serious long term health effects. Legionnaires disease is a potentially fatal form of pneumonia. Legionnaires' disease can have symptoms like many other forms of pneumonia, so it can be hard to diagnose at first. Signs of Legionnaires' disease can include: Cough Shortness of breath High fever Muscle aches Headaches These symptoms usually begin 2 to 14 days after being exposed to the bacteria.the parasitic relationship that Legionella has with its host the amoeba helps with its virulence. Once it gets into the lungs it can attack cells in the immune system called phagocytes. These act in a similar way to amoeba. In normal circumstances they form part of the body s defence system engulfing and destroying foreign organisms that such as bacteria that get into the body. However, Legionella multiply inside these phagocytes and when the cycle is complete burst out. This is one reason why if the illness is left unchecked can kill. Legionella can also cause a more mild form of the disease called Pontiac fever.this illness was names after the place of discovery: Pontiac, Michigan. The symptoms of this disease include fever and muscle aches. It is self-contained, usually running its course in two to five days. Treatment is rarely necessary. Legionella cannot be contracted by person to person contact

4 Who is at greatest risk from Legionnaires disease? It can affect anybody, but some people are at higher risk including those over 45, smokers and heavy drinkers, those suffering from chronic respiratory or kidney disease, and people whose immune system is impaired. In addition, males are more likely to become infected with L. pneumophila than women. If left untreated, the disease has a 5-80% mortality rate. Recently there has been an increase in the number of younger people also contracting the disease. How many species of Legionella organism are known? There are at least 40 different species of Legionella but only a few can cause illness. L. pneumophila causes about 90% of cases. Sixteen different serogroups of L. pneumophila have been described; however, L. pneumophila serogroup 1 is most commonly associated with cases of Legionnaires disease in the UK. In addition L. micdadei, is responsible for a similar form of the illness without pneumonia called Lochgoilhead fever after an outbreak in Lochgoilhead, Scotland. How is Legionnaires' disease diagnosed? In the most cases people with Legionnaires' disease will have developed pneumonia (lung infection) since the Legionella bacteria grow and thrive in the lungs. Pneumonia can be confirmed either by chest x-ray or by physical examination. In milder cases of the disease several laboratory tests can be used to detect the Legionella bacteria within the body: 1) The most commonly used laboratory test for diagnosis is the urinary antigen test. This is like a pregnancy testing kit which can detect protein from the Legionella bacteria in urine. If the patient has flu or pneumonia like symptoms and the test is positive, then the patient is considered to have Legionnaires' disease. 2) Samples of sputum (phlegm) or a lung biopsy specimen, or from various other sites, are taken and the samples are tested for Legionella bacteria. If the Legionella bacteria is cultured (isolated and grown on special media) then the diagnosis of Legionnaires disease is confirmed. 3) Blood specimens that show a four-fold increase in antibody levels when drawn shortly after illness and several weeks following recovery can also be used to confirm the diagnosis. Pontiac s disease can be confirmed by the urine test or by taking blood tests but the culture method does not help with the diagnosis of Pontiac fever.

Why does my water supply need to be checked? The Legionella organism can easily colonise man made water systems, and can colonise stagnant and still water.

Other potential sources of legionella include spa and whirlpool baths.

These organisms are able to grow and survive at temperatures below 60 o C.

5 Why does my water supply need to be checked? The Legionella organism can easily colonise man made water systems, and can colonise stagnant and still water. We usually associate legionella with larger water systems, e.g. in factories, hotels, hospitals and cooling towers, but they can also live in smaller water supply systems used in homes. Other potential sources of legionella include spa and whirlpool baths. Legionella organisms can survive and grow in hot and cold water systems and storage tanks in residential properties and then spread as aerosols from shower heads and taps. These organisms are able to grow and survive at temperatures below 60 o C. However as the temperature falls below 37 o C, the bacteria s reproductive rate decreases and when the temperature falls below 20 o C there is little or no growth. Therefore, to prevent Legionella infection, the recommended temperature for storage and distribution of cold water is below 25 o C, and ideally below 20 o C. Recent laboratory studies of Legionella have shown that the bacteria may be capable of growth below 20 o C under certain conditions. Legionella have also been shown to survive for long periods at low temperatures and then proliferate when the temperature increases. These bacteria can grow readily at temperatures in the range 20 o C to 45 o C and such temperatures are not uncommon at the base of conventional hot water storage vessels which have not been regularly maintained. In such environments Legionella, can be found in concentrations of 100,000 colony forming units per litre (cfu/l) and higher. Under optimum conditions, Legionella bacteria can multiply from background numbers to dangerous concentrations in less than five days. If unchecked these organisms can get into the water pipework and be released from shower heads or taps as water aerosols. The organism requires a source of food to survive. This can be found in areas where scaling can occur or where a biofilm develops. (A biofilm is a collection of algae, bacteria, mould and even single celled organisms such as amoeba forming a film on the surface of water). Biofilms, which may include legionellae and protozoa such as amoeba, can form on the surfaces of poorly managed header tanks, in water pipework and even in showerheads and taps The biofilm will contain the nutrients for growth and allow for gaseous exchange of waste products, and can protect microorganisms not only from cleaning agents such as chlorine compounds but also from periodic increases in temperature and attempts at physical removal, especially in areas where surfaces are scaled or corroded. Biofilms are more likely to form where there are areas of low water flow and where water is allowed to stagnate. The presence of biofilms is therefore an important factor for Legionella survival and growth in water systems. Biofilm prevention is an important control measure against proliferation of Legionella. Preventing the growth of biofilms is important because, once established, they are difficult to remove. The factors that increase the likelihood of biofilm formation, including: > The presence of nutrients, these can be found in the water source or in the materials making up the water system > Scale and corrosion > Warm water temperatures > Stagnation or low flow that can occur in the dead ends of water system pipework and in storage tanks

The presence of scale and corrosion in a system will allow the formation of micro-niches that can protect organisms from circulating disinfectants.

Uncontrolled biofilms can build up in pipework, resulting in areas of poor flow and stagnation with higher risk of Legionella growth. Furthermore biofilm and bacteria (including Legionella spp.

Legionella contamination can originate from small areas of a water system that have not been exposed to high temperature or circulating disinfectant.

6 The presence of scale and corrosion in a system will allow the formation of micro-niches that can protect organisms from circulating disinfectants. Scale and corrosion can also increase the concentration of nutrients in the water system. Uncontrolled biofilms can build up in pipework, resulting in areas of poor flow and stagnation with higher risk of Legionella growth. Furthermore biofilm and bacteria (including Legionella spp.) that have grown inside amoeba are more tolerant of chlorine and other antimicrobial agents at concentrations above those commonly used to disinfect water supplies. Legionella contamination can originate from small areas of a water system that have not been exposed to high temperature or circulating disinfectant. An example of this occurred in a large teaching hospital in the United Kingdom. The Legionella organism was detected intermittently at one sentinel outlet, despite the fact that there was a comprehensive risk control regime in place. The source was eventually tracked down to a 10-centimetre length of water-filled pipe where there was little or no flow (a dead leg ). When this section of pipe was removed, further samples tested were found to be negative. LEGIONELLA CAN SURVIVE FOR LONG PERIODS IN LOW TEMPERATURES, THE PRESENCE OF BIOFILMS HELPS TO PROTECT THE ORGANISM FROM EXTREME TEMPERATURE AND CLEANING WHICH MAKES IT VERY DIFFICULT TO ERADICATE How do I know if my water supply is at risk? A risk assessment is carried out in your property. This will involve assessing your cold and hot water supply and determining whether it may have the potential to harbour the Legionella organism. As part of this process a sample of water will be taken. To remain valid, Legionella risk assessments must be reviewed at least every 2 years, or earlier if required, and updated as necessary. A litre of water will be collected in a sterile screw top plastic bottle containing a chemical that will neutralise any chlorine that maybe present. Where the water is to be collected will be determined from the risk assessment. The sample is stored at room temperature and in the dark until it has been submitted to our specialised laboratory for testing. How is the sample tested? The litre of water is filtered under vacuum through a filter which is designed to allow water through but retain all the bacteria that maybe present. This process concentrates the number of bacteria present in the water. The filter is washed in 5 millilitres of sterile water. Since this solution will contain all the organisms present in the sample some of these organisms may inhibit the growth of Legionella. Since Legionella is more resistant to acid and high temperature than most organisms likely to be found in water a portion of this solution is treated with an acid buffer and another portion is treated by increasing the temperature. Such actions should stop non Legionella organisms to grow. The non- treated solution, acid treated solution and heat treated solution are spread on three plates containing a media which has been specially formulated to grow Legionella. The plates are incubated for up to 10 days. During this time any Legionella bacteria present will multiply to form colonies known as colony forming units (cfu). The number of cfu is counted. This count is known as a presumptive count as it has not yet been confirmed whether the colonies seen are Legionella. Under ultraviolet light, colonies of several species (L. bozemanii, L. gormanii, L. dumoffii, L. anisa, L. cherrii, L. steigerwaltii, L. gratiana, L. tucsonensis and L. parisiensis) autofluoresce brilliant white; L. rubrilucens and L. erythra appear red. Colonies of L. pneumophila Typical Legionella colonies

7 How are results reported? If no legionella bacteria are detected then the result is reported as not detected with a count of <50cfu/litre (less than 50 colony forming units per litre). If colonies were isolated the count will be reported as the number of cfu per litre. If the colonies were not confirmed as L. pneumophila then the confirmation will be Legionella species which is abbreviated as spp. If the colonies were confirmed as L-pneumophila serogroup 1 then the confirmed result will be reported as Legionella pneumophila sg1. If the confirmed result is one of the other L.pneumophila serogroups (2-15) then the confirmed result will be reported as Legionella pneumophila sg What do the results mean? The Health and Safety Executive (HSE) have published guidelines on the actions to be taken following the results of Legionella sampling of hot and cold water systems. These guidelines are interpreted for domestic properties as follows: Legionella bacteria (cfu/litre) Less than 100 More than 100 but less than 1000 More than 1000 Action required System under control no action required A resample should be taken. If a similar count is found again, then a review of the risk assessment and control measures should be carried out to identify any remedial action required. The system should be resampled and an immediate review of control measures to identify any remedial action should be carried out. This action should include a thorough cleaning of the system. Due to the natural life cycle of Legionella and the complexity of sampling and testing it is generally considered that the actual numbers isolated from a single litre of water is like the tip of the iceberg when considering the likely levels that could be present in your water system. It is highly probable that the true number of organisms present could be at least 10 times those found in a single water sample. On this basis a count of 1000cfu/litre could be as high as 10,000cfu/litre in the actual water system. Such levels in the right environment could potentially cause illness. RISK ASSESSMENTS CARRIED OUT TO DATE ON DOMESTIC PROPERTIES HAS SHOWN THAT OVER 4% OF WATER SAMPLES TAKEN FROM RENTED PROPERTIES HAVE SHOWN SIGNIFICANT LEVELS OF THE LEGIONELLA ORGANISM WITH COUNTS AS HIGH AS 7500 CFU/LITRE. What happens if the result is greater than 1000? A review of the risk assessment will take place and if required control measures will be put in place. Further samples will be taken for testing and thermo disinfection will be initiated. If results are still high chemical disinfection may need to be considered.

8 What is a thermal disinfection? It is the effectiveness of inactivating Legionella bacteria using raised temperatures (Thermal disinfection) and depends upon the temperature and how long the bacteria are exposed to that temperature. The water temperature coming from the tap or shower head is raised to 50 o C or higher. The length of time that the tap or shower should be run at this temperature will be dependent on the number of legionella organisms found in the water sample. For example, Legionella pneumophila requires on average 3.2 minutes exposure to 60 o C to inactivate 90% of the bacteria. Therefore, if the water contained 100,000 cfu/l of Legionella, the temperature will need to be held at 60 o C for approximately 10 minutes to reduce numbers to below the action level of 100 cfu/l. Generally, Hot water storage cylinders that maintain a temperature of 60 o C throughout the whole storage vessel for a period of one hour daily should achieve satisfactory control of Legionella bacteria, but other factors such as the cleanliness of header tanks, the pipework system, cleanliness of shower heads etc. may also have an effect on the survival of the organism in your system. Further Information Further information regarding the Legionella organism and its control in cold and hot water system can be found on the HSE website at

Legionnaires Disease Q&A (General) (Source: OSHA) (4/29/10)

Legionnaires Disease Q&A (General) (Source: OSHA) (4/29/10) Q. What is Legionnaires Disease? A. Legionnaires disease is a common name for one of the several illnesses caused by Legionella bacteria. Legionnaires