Essay proposal on Legionella Bacteria from a Cooling Tower

Introduction

Legionella is a common bacterium normally present naturally in many bodies of water including dams, streams, through which it moves through artificial reservoirs such as hotels, clinics, cooling towers in buildings and industrial process units Temperatures varying through 20 °C to 45 °C with dehydration, mud, sludge, size, rust and microbial multiples (European Guidelines Working Group, 2019). Legionella can develop in biofilms, contributing to increased transmissibility (Abdel-Nour, Duncan, Low & Guyard, 2013). Nevertheless, CTs are a component of the AC devices frequently used in big structures, including hotels or clinics, and running water to rapidly normalize air by heat loss. Several microbes in environment can thrive in improperly managed CT arrangements. The involvement of sediments, contaminants, heterotrophic biofilm and amoebae in warm CT meteors have been recorded to spread over many meters during certain incidents (Nhu Nguyen et al., 2006). Infected individuals who breathe aerosols including Legionella are at risk of acquiring LDs. CTs is related to multiple recorded LD events.

Ventilation of heat conditioning of cooling towers and evaporative condensers is commonly utilized for heat dissipation from air conditioning, filtration, and manufacturing processes systems. These contain, for the most part, open-circuit cooling towers that vary in scale from modest air-conditioning to massive towers for severe automotive purposes (Broadbent, 2002). Aerosols produced from open cooling towers can spread legionellae to intermediate hosts over greater distances and trigger legionellae in the population and also in clinics (Špaleková, Kotrbancová, Fulová & Šimonyiová, 2019). It is crucial that CT is controlled to avoid the proliferation of legionella and subsequent release of infected aerosols. Hence the most effective preventive measures are disinfection of biocides, quality control of recirculating water in CT holding bodies of water and surveillance of legionellae, chemical and biochemical increase performance to legionellae (European Guidelines Working Group, 2019). Regulation and identification of cooling towers can avoid certain accumulated legionella population outbreaks which is of major complaint to commercial CT (Fitzhenry et al., 2017).

Background

In the tragic year of 1976, 201 individuals residing at a hotel in Philadelphia, USA, suffering from disease of respiratory which later on identified as the disease known as Legionnaires. The causative factor, a previously observed microorganism, Legionella pneumophila serogroup, was identified later in the 6 month time period of examination by investigators from the Centers for Disease Control in Atlanta, USA.  Since then several more Legionella classes have been defined, and there has been a classification of certain organisms into serogroups. In total, 50 legionella types were recorded, consisting of 70 unique serogroups of which 40, that is, 20 subspecies were linked to human infection (Fields, Benson & Besser 2002). After 1976, incidents of Legionnaires ‘ disease have increased throughout the world and isolated reports have outgrown significantly.

Source: South Australia Department of Health (2008)

Shortly after the discovery of Legionella pneumophila as the causative organisms of this contagious diseases, CTs were believed to be a serious ecological cause of Legionnaires ‘ disease (Pereira, Peplies, Höfle & Brettar, 2017). Several research have since shown that cooling towers are a significant cause of infections and intermittent cases of legionellosis in industrialized countries (Walser et al., 2014). Generally speaking, the aggregate water of the cooling towers must be regarded as a large basin for Legionella bacteria, and a thorough knowledge of their frequency and survival is highly important for human safety. Long-term experiments utilizing biochemical methods coupled with control of environmental environments have achieved a deeper picture of the diversity of human organisms in marine microbial ecosystems during the past decade.

Research Questions

Following are the research questions that will need to be addressed:

1. What is the impact of legionella bacteria from a cooling tower on human health?
2. How to control the risk associated with the exposure to legionella bacteria from a cooling tower?

Scope of the study (Hazard / Issues)

While studying about the spread of legionella, it is found that only 0.1 to 5% of the individuals, exposed to the bacteria develop the disease, while others remain completely healthy. It is mentioned by researchers that even though all workers are not likely to develop legionnaire upon exposure, yet the contamination should not be overlooked and immediate actions should be taken to address the issue (Whiley, Keegan, Fallowfield & Ross, 2014; Oggioni et al., 2016). Additionally, it is imperative to study the varying risk factors of disease among different individuals developing the disease. When people, who develop the disease, have differentiated risk factors, then early consideration is needed by the management (Oggioni et al., 2016). In terms of hazard assessment, both the employers as well as workers (more specifically maintenance workers) need to be aware of the conditions which are linked with enhanced growth of legionella (Crook et al., 2020). The areas where bacterial growth is most likely, should be monitored periodically for detecting the early signs of bacterium presence. The most needed areas of assessment are;

• Locations where water might stagnate and flow of water is not maintained
• Water storage system
• Hot water maintenance systems
• Any side stream equipment, whereby regular flow is not maintained, such as by-pass lines
• Any devices used for prevention of back flow

Moreover, there are some conditions which are more favorable than others, for the growth of legionella. For instance, it is notable that when temperatures are above 140°F, then there prevails lower risk regarding the development of disease (Kusnetsov et al., 2010). Therefore, when water systems are not managed in effective way and temperature is low then the recommended, then there are enhanced chances of developing legionella (Carson & Mumford, 2010).

Literature Review

Legionnaires’ disease (LD) is a serious and highly lethal disease like pneumonia triggered by the Legionella species of many types of bacteria. The species Legionella pneumophila is accountable for more than 90 per cent of patients (Kozak-Muiznieks et al., 2014). Only certain species, including L. longbeachae, L. bozemanii, and L. dumoffii cause the remaining 10 per cent of patients. Longbeachae, the. Bozemanii, L. Dumoffii (2020, Paranjape et al.). In fact, LD is induced by inhaling polluted aerosols. Engineered water systems (EWS), including water delivery networks, storage tanks, drinking fountains, dehumidifiers and whirlpool spa treatments, are therefore reservoirs of bacterial propagation (Paranjape et al., 2020). Conversely, drinking water systems are by far the most frequent source of LD epidemics, CTs are a significant source of considerable population-related epidemics and near about 28 per cent of all sporadic patients (Fitzhenry et al., 2017; Llewellyn et al., 2017).

Legionella bacteria live in natural water bodies like rivers, lakes and streams at small concentrations, with negligible chance of triggering infections in humans. Nevertheless, once they populate and propagate in built environment water systems, then aerosol production spreads and a sensitive person inhales, bursts of respiratory disease can arise. Cold and hot water platforms, spa bathtubs and industrial emissions utilizing wastewater treatment risk triggering possibly deadly Legionnaire ‘s disease (LD) pneumonia (Crook et al., 2020).

Cooling can be accomplished by utilizing CTs or evaporative condensers, typically called to as evaporative cooling systems (ECS), as needed by production plants to drain away unnecessary steam, or for cooling / chilling. Generally these massive airflows and splattered water functionality with temperature differentials, and such systems are likely to produce an aerosol. Many, though not all, aerosols would be captured by concrete blockades on CTs to regulate this widely named drifted aluminum rims. Thus, if the cooling water becomes infected by Legionella, it may be spread over a large region, possibly damaging on-site staff, adjacent businesses or local public representatives (Crook et al., 2020). Considerations that lead to the development of Legionella bacteria in cooling water comprise the preservation and/or flow rate of water at temperatures around 20 and 45 ° C and a nutrient source, such as sludge, volume or losing possession (Tsao et al., 2019). It is therefore necessary to monitor development by ensuring a healthy plant and cycle water, and proper use of certified biocidal care, as well as growing the production or distribution of aerosols. Sporadic cases of Legionelloses were triggered by polluted water supplies in the environment, which included ECS. These varied in scale compared of both faeces of bacterial people and severity (chronic disease and accidental death). This is thus a serious public health problem, especially in heavily populated regions or even when polluted ECS is placed close vulnerable individuals, such as health care facilities.

Proposed Strategy

Preventing exposure to Legionellain buildings

Cooling Towers

In air conditioning systems, CTs are the one that remove heat obtained from air condition areas, and in industry to eliminate heat produced by several manufacturing processes. There are several various styles of part of establishing, each with common network characteristics. Water flows from a pool at the bottom of the structures and moves to the top of the structure in which it flows into a framework built to build a moist environment into which air travels.

Scheme and structure of CTs should be extremely durable and non – corrosive, with incredibly simple substrates to rinse. Interior surfaces should be seamless, and sharp edges balanced to make life a lot easier. The architecture of the tower would allow easy accessibility to the tower’s inner walls such as the fill. Towers should really be built to achieve rapid cleaning of parts, especially drift eliminators. Large access panels should be in place to enable complete movement of modules when needed. Basins and drainage channels will be classified to channels with fast infiltration and flooding arrangements.

The cooling towers should be positioned far back from other air processing facilities, ventilation filters, other building entrances, ventilation systems discharges, and open access regions. While finding a cooling tower, account should be made of the impact of adjacent buildings and also of predominant wind patterns. While the tower fan is stationary, attention will be given to the reverse impact or air movement across certain buildings. In some cases, rehabilitation of cooling towers or cooling ducts should be contemplated, especially if they are located close to one another.

General Layout of cooling tower

The normal configuration of an AC unit is shown in Fig 2. The CT water absorbs heat from heat exchanger flowing over to the compressor and releases heat to the warm air by evaporative cooling and mantle convection and energy efficient distribution of heat during the cycle of being spread over the tower load. The airflow function is either activated or triggered by draught.

Source: The Control of Legionellosis (Guidelines for Public Health Units Revised edition)

Risk Analysis

The CTs are a most important basis of Legionnaires’ environmental spread. For illustration, a large epidemic of Legionnaires ‘ disease in New York in 2015, triggered by a cooling tower, deeply saddened 138 killed at least 16 (Lapierre et al., 2017). Water inside cooling towers is insulated by heating process, a mechanism that provides optimal conditions for water-loving Legionella bacteria to evolve. CDC investigation found that 84% of the cooling towers evaluated in the US had a significant outcome for Legionella DNA since 194, indicating that the bacteria were prevalent in the system over time. (Llewellyn et al., 2017).

Elements that leads to high risk of Legionella bacteria in Cooling Towers 

• Temperature: The sides are accessible in several cooling towers, enabling for sunlight to enter the basin of the CT and enabling algae to emerge. It is necessary to shield the CT basin from illumination, as the water temperature in the structure has a significant influence on the rate of development of Legionella (Paniagua, Paranjape, Hu, Bedard & Faucher, 2020).
• Aerosol generation: Due to their potential to disperse Legionella across a large region, cooling towers are known to be among the highly hazardous and tightly controlled water treatment and Legionella management industries. (Crook et al., 2020).
• Stagnant Water: Stagnant water areas may stop the towers from being effectively chemical treated and enable Legionella and its hosts to thrive (Chamberlain, Lehnert & Berkelman, 2017).
• Production of biofilms: Cooling towers regularly rinse the air while they work and thus accumulate garbage, soil and dust regularly throughout the cooling phase. Based on the area of the cooling tower, the volume of stuff obtained in the water can be substantial and can lead to the expansion of biofilms that deliver Legionella with nutrients for sustenance and development (Brouse, Brouse & Brouse, 2017).
• Regular Testing methods: Staffing function in refrigeration towers are always suggested to take water samples to a research lab (Barrette, 2019).
• Quality of Water: Water that typically comes from either a public or well source, but may sometimes flow from a storage tank and can involve sediment, corrosion, and salt. More widely employed, groundwater from streams, ponds, or ponds may be composed of aquatic microbes and minerals (Racine, Elliott & Betts, 2019).

Control Measures

Followed by the identification of maintenance issues, or diagnosis of any worker with the disease, the immediate action requires the employers to shut down the source of infection. For instance, in case of AC cooling tower, being the risk of infection, there is need to carry out maintenance of the underlying water system for decontaminating the cooling tower from legionella bacterium. The legionella sampling and use of biofilms might be considered an appropriate way to detect the signs of bacteria followed by maintenance of the water system. Followed by this, the other action require the employers to extend communication with the employees who are at greater risk of exposure or who might have inhaled the bacterium through aerosolized air. By following these steps, legionnaire might be addressed in timely manner, restricting the further spread of disease.

Conclusion

Cooling towers are the worldwide main cause of legionellosis spreads. Such infections are primarily associated with Legionella bacteria, predominantly Legionella pneumophila, and their monitoring in cooling tower environments is of wide public health significance. In this essay, the main point of address is Legionella bacteria, its emergences, causes, factors and risk associated with it on human health. Moreover, AC cooling towers are considered as key source for developing the legionella and inhaling of contaminated air might cause spread of disease and this is part of other water maintenance systems. The hazards can be assessed to detect the early signs of legionella in vulnerable spots and management is needed to shut down the contaminated water systems on immediate basis to assure that spread of disease is controlled.  The proper control and management is required to counter is fatal disease and protect the human health and environments overall.

References

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Barrette, I. (2019). Comparison of Legiolert and a Conventional Culture Method for Detection of Legionella pneumophila from Cooling Towers in Québec. Journal of AOAC International, 102(4), 1235-1240.

Broadbent, C. (2002). Australian Risk Management Approaches to Control of Legtonella in Cooling Water Systems. In Legionella (pp. 371-375). American Society of Microbiology.

Brouse, L., Brouse, R., & Brouse, D. (2017). Natural pathogen control chemistry to replace toxic treatment of microbes and biofilm in cooling towers. Pathogens, 6(2), 14.

Carson, P., & Mumford, C. (2010). Legionnaires’ disease: causation, prevention and control. Loss Prevention Bulletin, (216).

Chamberlain, A. T., Lehnert, J. D., & Berkelman, R. L. (2017). The 2015 New York City Legionnaires’ Disease Outbreak: A Case Study on a History-Making Outbreak. Journal of Public Health Management and Practice, 23(4), 410.

Crook, B., Willerton, L., Smith, D., Wilson, L., Poran, V., Helps, J., & McDermott, P. (2020). Legionella risk in evaporative cooling systems and underlying causes of associated breaches in health and safety compliance. International Journal of Hygiene and Environmental Health, 224, 113425.

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