Legionella are bacteria that live naturally in rivers, lakes and damp soil. In small numbers they do no harm. The problem starts when they get into man-made water systems and multiply. If people then breathe in tiny droplets of that water, they can become seriously ill.
This course gives you awareness. It tells you what legionella is, why it matters and what you can do. It does not make you a responsible person for a water system. You will read more about that at the end.
Legionnaires' disease
Legionnaires' disease is a serious type of pneumonia, a lung infection. It is caused by legionella bacteria, most often the species Legionella pneumophila.
- Early symptoms feel like flu: high temperature, tiredness, headache and muscle pain.
- A dry cough and shortness of breath often follow.
- Some people also have diarrhoea, confusion or chest pain.
- Symptoms usually start two to ten days after exposure.
- It is treated with antibiotics. Some people become very ill, and some die.
Pontiac fever
Pontiac fever is a milder illness caused by the same bacteria. It brings flu-like symptoms but not pneumonia. It usually goes away by itself in a few days. Doctors group both illnesses under the name legionellosis.
How people catch it
People catch legionella by breathing in an aerosol: a fine mist of water droplets that contains the bacteria. Examples are the spray from a shower, a spa pool or a cooling tower.
- Drinking contaminated water is not the usual route. The risk is mainly from breathing in the mist.
- Legionnaires' disease does not normally pass from one person to another.
- A single tap or shower can be a source if conditions are poor.
Why this is a workplace issue
Workplaces have many water outlets, tanks and pipes, and some have cooling systems. If nobody manages them, legionella can grow. Employees, visitors, patients, residents and customers can all be exposed. Outbreaks have caused deaths in the UK, which is why the law asks employers to control the risk.
Key points
- Legionella is a bacterium that grows in warm, still water.
- It causes Legionnaires' disease (pneumonia) and Pontiac fever (milder).
- You catch it by breathing in a mist of contaminated water.
- It is not normally passed from person to person.
- Good control stops the bacteria from growing in the first place.
A short history
The disease got its name in 1976. Members of the American Legion, a group of veterans, met at a hotel in Philadelphia in the United States, and many fell ill with pneumonia. Investigators later traced the bacterium to the hotel's air-conditioning system. Since then, outbreaks linked to cooling towers, spa pools and hot and cold water systems have been found in many countries, the UK included. The lesson from them is always the same: the bacteria were allowed to grow because nobody was managing the water.
Why prevention beats treatment
There is no vaccine against legionella. Treatment works best when it starts early, but for older people and those with other illnesses the infection can still be fatal. For that reason, the law concentrates on prevention. An employer who keeps water systems clean, moving and at the right temperature takes away the conditions that the bacteria need.
Everyday examples
Think about the places where you might breathe in a water mist at work or in a public building: a hotel shower, a gym changing room, a hospital ward, a care home bathroom, a hot tub at a leisure centre, a car wash, or the outside of a factory with a cooling tower on the roof. In each case, the question is the same. Is warm, still water allowed to sit there, and can it make a mist?