Infectious diseases have become a global problem as a result of the abundance and diversity of transportation possibilities. Travel-associated Legionnaires Disease, which has been observed in our country since 1996, is one of these issues. Since Legionnaires' disease is linked to water, it has been well known that it is not only linked to travel, but also to other living environments where water is used in the environment.

 

Legionella bacteria, as a disease factor, can spread from natural waters to indoor water systems, where they can settle and reproduce. The bacteria in the water supply infects the human, causing the disease to evolve. The disease may manifest itself as a single case or as an epidemic. It is critical for public health because the disease has the ability to spread from an environmental source and cause an outbreak. Legionnaires' disease is one of our country's notifiable diseases, and a special program is carried out to control the disease.

 

The most common colonization environments of Legionella bacteria are building water systems (areas above 20 °C and below 50 °C), thermal springs, hot pools, fountains, steam condensers, respiratory therapy equipment in hospitals - especially when tap water is used in water reservoirs, the possibility of colonization of the bacteria increases.

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It is broadly understood that the bacteria can infect a human and enter the lungs in one of two ways. Inhaling water aerosols carrying Legionella that are absorbed into the breathing air from environmental sources is the most commonly known method.  According to a study, shower heads and hot water taps carrying L. pneumophila were found to aerosolize the microorganism, with aerosol particles small enough (1-5 µm) to infiltrate the lower respiratory tract.

 

When a case of Legionnaires' Disease is identified in our country, an environmental analysis is launched to help with case monitoring as part of the "Legionnaires' Disease Control Program." The analysis to be conducted in the accommodation units where incidents are registered is performed together by the Public Health Directorates' Communicable Diseases and Environmental Health units for this reason. When a case notice is obtained, the water in the accommodation unit is heated to over 70 °C, decontamination procedures are carried out, and water samples are collected for Legionella analysis.

 

Furthermore, there are still routine control procedures that should be carried out in accommodation units where there is no case of legionnaire disease but the risk is high due to the population and accommodation unit characteristics. Even if there no cases, hospital water supplies should be inspected for Legionella colonization on a regular basis, and the efficacy of routine prevention measures in hospitals should be assessed.

 

In routine measures, water tanks are emptied, cleaned and disinfected at least once every 6 months and hot water tanks at least four times a year, depending on sediment accumulation. If a hot water tank or a part of the hot water system has been out of service for a week or more due to maintenance and similar reasons, the temperature of the water is kept above 70 °C for at least 24 hours from the time it is put into use again. The temperature of the water in the hot water tanks is kept at a level of at least 60 °C throughout the year. Water flows from the taps and shower heads of unused rooms for 3-5 minutes every day. All dead spaces detected in the installation are immediately eliminated, unused branches are removed.

 

According to a research conducted in 2007, 491 samples were collected from 52 hotels in Antalya, Turkey. Legionella bacteria were detected in 36 of the samples out of 93. In these 93 samples, 86 of the Legionella bacterium species were found to be L. pneumophila, which is the most dangerous species for human health.

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Legionella tests should only be performed in laboratories that are equipped to meet biosafety level 2 requirements. However, the samples taken from the patient or the atmosphere must be sent to these labs within a certain amount of time and at a certain temperature in order to be analyzed. In most cases, the sample must be shipped on dry ice in less than 48 hours (-70 °C). Since the analyzes are based on the growth of the bacteria in the suspect sample collected in the nutrient medium, the detection period can take up to 5 days.

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Currently, sensing surfaces used in sensors consist of biobased (DNA, Aptamer, PNA, Antibody etc.) and nanostructured materials (metal oxide, two-dimensional, quantum particle, etc.). Each of the materials used in various sensor structures (such as SAW, chemical resistance (chemiresistive), LAMP, and optics) has its own set of benefits and drawbacks. Within the scope of the proposed project, it is anticipated to develop hybrid systems with low Limits of Detection (LOD) values and high sensitivity and specificity by combining the best characteristics of these systems.