Legionnaires’ disease
Legionnaires’ disease, is a form of pneumonia (lung infection). It does not have specific symptoms or signs that make it different from other types of pneumonia, so doctors need to perform tests to confirm the diagnosis.
Symptoms may show from 2 days to usually 5 to 6 days from infection, but sometimes it can take longer. It often starts with a dry cough, fever, headache, and sometimes diarrhoea or confusion before the onset of pneumonia.
Key facts
Risk for people
The mortality rate of Legionnaires’ disease varies between 5% and 15%, depending on the age and individual health status. People over the age of 50 are more at risk than younger people, as well as immunocompromised or persons with underlying illness. . Smokers are also a risk group.
How it spreads
People can get infected when they breathe in tiny water droplets called aerosols that carry the Legionella bacteria . If these bacteria go into the lungs, they can cause an infection. Legionnaires’ disease cannot be transmitted by consuming drinking water: the bacterium has to reach the respiratory system through breathing or accidental inhalation into the lungs . The illness is not spread from person to person.
Legionella bacteria are quite common in the environment and naturally exist in water sources such as rivers, lakes, and reservoirs. They may also be found in soil and compost. These bacteria can survive in different temperatures in the environment. They may also grow in engineered water systems, most often associated with buildings and plumbing such as hot and cold water systems, cooling towers, humidifiers, fountains and hot tubs . Gardening and wastewater treatment plants have also been associated to outbreaks.
Vaccination and treatment
There is currently no available vaccination against developing Legionnaires’ disease. If the diagnosis is made early enough, there are effective antibiotics that work well for treatment.
Protective measures
The main protective measure is to reduce risk of Legionella growth in places that produce aerosol droplets that can be breathed in. .
Regular checks for the presence of Legionella bacteria and appropriate control measures can help prevent cases of Legionnaires’ disease in places where people who may be at higher risk of the disease might be more likely to be exposed. These include tourist accommodation sites, hospitals and long-term healthcare facilities. Effective control measures against legionella bacteria include:
- Ensuring regular maintenance, cleaning, and disinfection of water systems, including plumbing systems, cooling towers, hot tubs, and decorative fountains.
- Maintaining cold-water systems below 20°C, and hot-water systems above 50°C to prevent bacterial growth.
- Ensuring proper water flow and circulation in water systems to minimize the risk of stagnant water.
- Disinfecting hot water systems with high levels of (50mg/l) chlorine for 2–4 hours after work on the system and water heaters, and before the beginning of every warm season.
- Regularly cleaning and disinfecting water filters, cooling towers and associated pipes used in air conditioning systems.
