This article looks at the dangers of Legionella? If you wanted to know more about Legionella and the risks from the disease, find out more here.
What Are The Dangers Of Legionella?
Legionella is a type of bacteria that lives in water. When people breathe in tiny droplets of water that contain legionella bacteria, they can develop legionnaires’ disease.
This disease is a potentially fatal form of pneumonia. It can also cause a milder illness called Pontiac fever. The risk increases when a water system is not well managed or when the water temperature allows the bacteria to grow.
Where legionella bacteria grow
Legionella bacteria grow best in warm water that is between 20°C and 45°C. They use nutrients found in sludge, scale and organic matter. If a water system stands still, the bacteria can multiply.
This can happen in hot and cold water systems, spa pools, hot tubs, showers and cooling towers. Poorly maintained air conditioning that uses water in cooling towers can be a source, but the small units in homes and cars do not use water and are not a source.
In large buildings, such as hotels, hospitals and offices, long pipe runs and low flow can let the bacteria develop. Cold water systems that are not kept cold and hot water that is not kept hot can both present risks.
After long closures, for example during lockdowns, many premises needed a full review because water had stagnated. Without the right control measures, growth can lead to outbreaks.
How infection happens
Infection happens when a person breathes in aerosols, which are droplets of water that are small enough to carry into the lungs. This may come from taps, showers, cooling towers or spa pools.
The disease does not usually spread from person to person. Drinking water is not a common route of exposure, although aspiration of water into the lungs can cause infections in some people.
Who is at higher risk
Anyone can get legionnaires’ disease, but some people have higher risks. Age over 50, smoking, chronic lung disease, diabetes, cancer, kidney disease and weak immune systems all increase the chance of severe infection.
People who take drugs that suppress the immune system are also at greater risk. Most infections are linked to exposure in buildings where water systems are present, such as hospitals or hotels.
Symptoms of legionnaires’ disease and Pontiac fever
The symptoms of legionnaires’ disease often start with a high fever, chills, headache and muscle aches. Within a few days, symptoms of legionnaires’ disease can include cough, chest pain, nausea, diarrhoea, confusion and shortness of breath. This disease is a potentially fatal form of pneumonia and needs prompt medical care.
Pontiac fever is different. It causes fever, headache and muscle aches but does not cause pneumonia. Symptoms usually develop within a few hours to three days after exposure and tend to clear within two to five days.
Diagnosis and treatment
Doctors diagnose legionnaires’ disease using tests on urine, sputum or a swab from the lungs. A chest X-ray can show pneumonia but cannot identify the exact cause on its own.
Most people need hospital care. Treatment is with antibiotics. These are often given into a vein at first, then as tablets for one to three weeks. Without quick treatment, the disease can lead to serious problems, such as respiratory failure, acute kidney failure and septic shock.
Common sources and examples
Many cases have been linked to cooling towers, spa pools, showers and other water systems that make water droplets.
For example, a poorly controlled hotel water system can become a source of exposure for many people.
When outbreaks are identified, health teams investigate the likely source and check whether sludge, scale and organic matter have built up.
They also check whether water temperature is correct and whether biocide levels are present where used.
Control of legionella in water systems
Good control is based on risk assessment, regular checks and clear action if problems are found. Employers and landlords should have a scheme for the control of legionella. This includes:
- Keeping hot water hot and cold water cold, so the water temperature does not sit in the growth range.
- Flushing little-used outlets to prevent stagnation in the water system.
- Cleaning and descaling showers, taps and spa pools to remove nutrients and scale.
- Using biocides where needed and checking residual levels.
- Sampling and reviewing results after changes or if an issue is suspected.
- Recording information in a log, so any patterns can be identified and a complete report can be kept.
Although lists help planning, the real focus is steady action. Regular inspections, temperature monitoring and prompt cleaning limit growth. Good control measures reduce risks and help prevent disease.
Responsibilities and health and safety
Employers have legal duties to protect people who use their premises. They must assess the risks, put control measures in place, and keep records. If a new use or type of system is installed, carry out a fresh review.
Health and safety law expects clear management, trained people and a plan for action if results show a problem. If an outbreak is suspected, the system should be taken out of use if needed and investigated.
Authorities may ask for a page from your site or a formal report that shows what is present in the system and what action has been taken.
After an outbreak or positive result
When legionella is identified, the source must be controlled. This may include raising water temperature, shock disinfection, cleaning to remove sludge, scale and organic matter, and improving the design of the system.
Cooling towers may need deep cleaning and a change to dosing or filtration. A follow-up review checks that control is effective and that infections linked to the premises have stopped. Information from lab tests and site checks helps confirm the source and guide future control.
Reducing your personal risk
You can lower your personal risk by not smoking, limiting alcohol and seeking early medical help if you develop pneumonia symptoms after likely exposure.
People with long-term illness should be alert to symptoms after stays in hotels or hospitals.
If you are unwell after exposure to water systems, tell your doctor about any recent travel or nights away and mention possible exposure to water aerosols.
The Dangers Of Legionella: Key points to remember
Legionnaires’ disease is serious but preventable. The main risks arise when water systems are poorly managed and conditions allow bacteria to grow. Good design, regular checks, correct water temperature and prompt action are vital.
Summary of Key terms :
Legionella bacteria: The bacteria that cause legionnaires’ disease and Pontiac fever.
Water droplets or aerosols: Tiny droplets that can be breathed deep into the lungs.
Water systems: Hot and cold water systems, spa pools and cooling towers where bacteria can grow.
Control measures: Practical steps to control legionella, such as flushing, cleaning, disinfection and temperature control.
Outbreaks: Two or more cases linked to the same source that may show a problem at a site or in a system.
If you need more information, speak to your healthcare provider or the responsible person for your building’s water systems. Many trusted resources are available on official health sites that use https in their web addresses, where you can read guidance on the control of legionella and the symptoms of legionnaires’ disease.
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