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Beware of bacteria
March 27, 2013   
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Bo瞠nna Toczy這wska, Ph.D., from the Building Research Institute in Warsaw, talks to Karolina Olszewska.

You coordinated the work of a research team that carried out a project called “Reducing risk to human health caused by Legionella bacteria in plumbing and air-conditioning systems in buildings.” What inspired you to become involved in that project?

The main inspiration was the health risk posed by Legionella bacteria, which are found in surface waters, in moist soil, in puddles and in standing water. The bacteria are not dangerous for humans unless they have multiplied in large quantities. The interesting and important thing about Legionella is that it is the only bacteria transmitted through water which causes respiratory system diseases, in contrast to all other bacteria of this type, which affect the digestive system. Legionella can be extremely dangerous to human health if it gets into the lungs in the form of a water-air mixture. Such is the case in, for instance, cooling towers, showers and car washes. Sometimes it also happens that Legionella bacteria attack the human body when you swallow some water in a swimming pool. Surprisingly, scientists have also discovered that even such an innocuous activity as brushing your teeth and rinsing with tap water may cause legionellosis in people with particularly low immunity.

Is this a rare occurrence?

Not really. The main problem is that the public, doctors included, know too little about it, chiefly when it comes to diagnostic procedures. Statistics help us grasp the scope of the problem. Data shows that just over 11 people per 1 million on average are affected worldwide every year. In Poland, from a dozen or so to 30 cases are diagnosed every year. There are two distinctive forms of legionellosis. The first is so-called legionnaires’ disease, the main symptom of which is pneumonia; the second form resembles flu and is called Pontiac fever.

Pneumonia is dangerous inasmuch as, in addition to high fever and vomiting, it often involves other problems, for example neurological in nature. I know of a man who has lost his hearing as a result of legionnaires’ disease. Although the probability of catching that disease is low, the mortality rate is rather high, up to 20 percent. And this is chiefly due to inadequate diagnosis methods. Patients often die because they are usually routinely treated with ordinary antibiotics instead of specific antibiotics. To diagnose legionellosis, doctors ought to analyze the patient’s history and have the clinical material examined. Unfortunately, it is not common in Poland to do so. And that’s the main reason for the high potential risk of that disease.

It is worth mentioning that the largest number of cases of legionellosis are recorded in South European countries such as Italy, France or Spain. Those countries have warm climates, which are favorable for the bacteria to multiply in installations, but on the other hand the diagnostic methods are relatively good there. It’s necessary to be aware that people with low immunity, such as cancer patients or people who have undergone transplants, as well as diabetics, habitual smokers and elderly people, are especially vulnerable to legionellosis. Men catch that disease three times more often than women. The most cases are recorded in August. Some other factors that heighten the risk are exhaustion and stress, which is why that disease is commonly associated with traveling.

You said these bacteria are not dangerous unless they multiply in large quantities. In what conditions does this happen?

Water with a temperature of 25-45 degrees Celsius promotes the multiplication of Legionella bacteria. High-risk spots chiefly include water installations where a water-air mixture is produced. Statistically, the greatest risk is in cooling towers. For instance, in Edinburgh in 2012, Legionella bacteria were found in a cooling tower at a whisky distillery. A total of 101 people fell ill and three died as a result of a legionellosis epidemic in the city.

But industrial installations are not the only source of those bacteria. Even regular showers may be a source of these bacteria.

Until recently, scientists used to think the bacteria are only found in warm water. Yet during our research we found out the risk may also arise in cold water.

A third major source of Legionella bacteria are hot tubs, also called jacuzzi or whirlpool bathtubs, where a water-air spray is produced with the use of nozzles or a stream of air. It is vital to follow the instructions for cleaning and disinfecting such appliances, and their users should know them for their own safety. Yet people tend to buy hot tubs and use them in the wrong way, which may result in health problems.

It should also be emphasized that swimming pools as well as fancy recreational pools are safe in terms of legionellosis.

Everyone ought to be familiar with the symptoms of infection and be aware of the conditions in which these bacteria multiply. For instance, if you have a house on a plot of land and a water tank where the temperature is 35-37蚓, which means optimal for the bacteria to multiply, even taking a shower may be dangerous. If the water installation was left unused for a long time, you should rinse it by flushing and heat it up periodically.

Legionella can even be found in windshield washer fluids. Therefore, you should use fluids that contain biocide, which should be listed on the label. It is also possible to catch legionellosis as a result of having contact with soil, for instance while transplanting flowers.

How did your research team deal with the risk posed by these bacteria?

In 1976, scientists for the first time found a correlation between the presence of Legionella bacteria in hotel air-conditioning systems and a large number of pneumonia cases there. After that, thanks to many long-term research projects, factors favorable to the multiplication of such bacteria were discovered as well as ways to fight them by means of disinfecting the installations and also the type of technical measures used to prevent the installations from getting contaminated. But that laboratory expertise and theoretical insight doesn’t solve any practical problems since one may take very costly measures and not get the expected result. The aim of our project was to find tools to enable us to assess the causes of the threat involved and come up with guidelines on how to maintain buildings and how to fight the bacteria and prevent them from multiplying.

Polish building design regulations in force since 2002 include recommendations sufficient for maintaining the proper state of installations. If these instructions were followed, everything would be fine. But unfortunately, often they are not; besides, they don’t apply to buildings built before 2002.

So our goal was to examine the real state of water installations in buildings in terms of Legionella contamination and to highlight potential risk factors. We tried to solve the problem in such a way so as to get rid of the bacteria and maintain that state for as long as possible.

What did you do specifically?

We chose different water installations in various buildings for our research. It covered two hospitals, a sports center with swimming pools, a hotel, two residential buildings, an office building, a museum, and two military facilities. We examined them and carried out proper maintenance procedures such as cleaning, disinfection and rinsing tanks, pipes, water ducts, water treatment systems etc. It should be emphasized that the basic and most often used way of fighting these bacteria is thermal disinfection, that is rinsing an installation with water at a temperature of no less than 70 degrees C. That method is efficient, but unfortunately only for disinfecting warm water systems. And it doesn’t prevent the installations from being infected again by the bacteria; besides, it tends to damage the installations and its effects last only three months. So we wanted to find other ways. For instance, we carried out disinfection procedures with various chemical methods (using sodium hypochlorite and chlorine dioxide) and UV radiation. In two oncologic hospitals, we installed devices that generate chlorine dioxide, which is the most efficient substance for fighting Legionella and preventing recontamination, as well as a UV lamp for continuous disinfection. We bought all these devices as part of our project. The generators are working and are a measurable effect of the project.

It also needs to be noted that almost all of the examined water systems needed modernization or modification in terms of how they are used. Of more than 20 warm water systems only one was free from bacteria, but the water temperature was 70蚓 there. In such conditions, the bacteria die but the installation is damaged as well.

In some buildings, we have implemented maintenance and bacteria-fighting procedures or designed modernization projects in order to reduce the risk of contamination.

After we finished the project, I revisited the facilities involved to check the state of their installations. It turned out that if all the recommendations were followed relating to, for instance, maintaining the proper water temperature or the disinfection, cleaning and rinsing procedures adapted to the type of installations and the conditions in which they are used, the installations were free from bacteria for the first time in years.

Specifically, what is innovative about the project?

Generally, the aim of the project was to work out a comprehensive range of measures to remove the potential risk of contamination with Legionella bacteria in warm and cold water installations as well as pool and air-conditioning systems in buildings. Another aim was to formulate recommendations on how these systems should be operated and maintained in order to obtain the best possible result at the lowest possible cost.

Of course, microbiological research and contamination assessment are performed by sanitary supervision services. But until now there was a lack of information on the correlation between the causes and effects, which means between the contamination level and the conditions in which various installations are used. This problem is purely technical; it’s a problem for engineers, operators and technicians.

The ultimate criterion in risk evaluation is the potential presence of microbiological contamination, but prevention is always better than cure. Specialists from various fields of science working together and a holistic approach to the problem of Legionella contamination is the main element of the innovation.

The project has had an impact on market practices…

According to World Health Organization (WHO) guidelines and the recommendations of the European Commission, preventing the risk posed by Legionella bacteria and providing water safety in installations should be treated on par with the need to ensure food safety in line with the principles of the Hazard Analysis Critical Control Point (HACCP) system. It’s an approach based on risk analysis and continuous monitoring of the situation. I’m working on water safety systems for buildings in order to minimize the risk posed by Legionella bacteria. There is already sufficient expertise in Poland to apply such systems. The rules for designing and operating installations are universal, but these rules need to be laid out on an individual basis for each system, preferably by an expert. The thing is that every building has its characteristic features and the universal principles need to be adapted to that. Under WHO and European regulations, it is recommended that a specialized external company audit a building every two years—in terms of operating conditions, not microbiological examination. We have developed the tools—analysis methods, tests, and measurements—to assess the influence of the technology, operating conditions and many other elements on the risk level and on the selection of optimal disinfection methods and the establishment of operating and monitoring procedures. However, it’s not scientists but sanitary supervision services that are responsible for checking residential facilities such as hotels, hospitals and dorms in terms of potential warm water contamination. Swimming pools, air-conditioning systems, cold tap water systems and fountains are not subject to inspection. It’s in the facility administrators’ own interest to follow the procedures so that there is no contamination. The Building Research Institute has issued guidelines for the design and operation of water supply systems and air-conditioning systems in buildings in order to protect users from Legionella.

ho developed these guidelines?

The team consisted of engineering professionals dealing with water installations in buildings and ventilation and air-conditioning systems. The group previously worked at the INSTAL Research and Development Center for Installation Technology [in Warsaw], and in 2007 it was made part of the Building Research Institute, where we continued to work on the project. The project manager was Bogdan Koz這wski, M.Sc., who dealt with problems related to the functioning of heating systems, one of the most important issues connected with legionellosis prevention. I was responsible for water quality and monitoring methods. The project lasted three years and we carried it out in association with the National Institute of Public Health (PZH).

We received zl.1.4 million from the National Center for Research and Development (NCBiR) for the project. We spent only zl.1.1 million because we eventually decided against buying equipment for fighting Legionella bacteria in air-conditioning systems. We had planned to buy that equipment but it turned out to be unnecessary as the results of our tests for those systems were good enough.
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