What is legionella?
Legionella are a group of water-borne, rod shaped bacteria that can cause Legionnaires disease, Pontiac Fever and Lochgoilhead fever. Around 90% of Legionnaires disease cases are caused by the species legionella pneumophila, however, there are at least 28 more species that are all human pathogens. Legionnaires disease is also called legionellosis or legionella-pneumonia and is a potentially fatal pneumonia.
Legionnaires disease first came to attention in 1976 during a conference at a large hotel in Philadelphia where 221 men out of a group of 4,000 suddenly fell ill with a pneumonia type illness. Thirty-four of those infected died of the, then unknown, lung disease. Due to the fact that all the infected people were members of a war veterans club, the American Legion, the bacterium, which was later found in the air-cooling system of the hotel, was called legionella pneumophila, and the disease was later called legionnaires disease.
Legionella bacteria can be found everywhere in natural water and ground water, but in very low concentrations. However, since the second half of the 20th century they have come into conflict with humans. This is due to the fact that we have developed technical water systems that provide ideal growth conditions for bacteria and have coupled these with human exposure routes. Additionally, since this time people have, for a variety of reasons (prolonged chronic illness, old age, smoking, drug use, immune suppressants etc.) become more susceptible to contracting the disease.
Where Does Legionella Come From?
The preferred areas where legionella pneumophila occur is in pipe systems, pumps and valves, air-cooling systems, air washing units, whirlpools, warm water systems, cold water systems (often due to poor thermal isolation), cooling towers and cooling circuits. They can often be found in retirement homes, hospitals, schools, hotels, public buildings, swimming pools and sport facilities. Old, poorly serviced or seldom used warm water systems and storage devices are areas where legionella can easily grow.
The bacteria multiply where temperatures are between 20°C and 45°C, but can survive in temperatures up to 60°C. In cold water systems they can appear in summer as result of high outside temperatures and when there is poor isolation of the cold water pipes and the temperatures in the piping become greater than 20°C. The bacteria thrive where there is also a nutrient source and where water flows are low or the water is stagnant.
As Legionella can double its population (if the surroundings are optimal) through cell division every three to four hours a build up of Legionella bacteria can occur quickly. Legionella is not a primary biofilm producer, however, biofilm plays a key role as it provides nutrition and protection for the legionella bacterium. Biofilm is also the habitat of different single-cell organisms in which Legionella are able to multiply. This strategy can also be transferred for human macrophages.
How Do You Get Legionella?
Legionella infection is caused by exposure to aerosols from a contaminated water system, no cases of transfer from human to human have been detected. The highest risk for a legionella infection is posed by breathing in contaminated respirable aerosols from a warm water system (e.g. taking showers). If the human immune system is effective it attacks and destroys the legionella bacteria before they can cause any damage. However, ill people and people who have a weak immune system (older people, immunosuppressed etc.) are at a greater risk of developing Legionnaires disease. Men are in general three times more likely to develop Legionnaires disease than women, the reasons for this gender specific occurrence are not known.
The factors that lead to Legionnaires disease include -
- Legionella must be present in the water.
- The legionella bacteria are multiplying to an infectious concentration (infection dose).
- The legionella spreads out of this water via aerosols to humans.
- The human body cannot (because of an immune weakness) fight the infection.
The legionella disease symptoms manifest themselves as a flu type illness together with fever (Pontiac fever) all the way through to a very serious pneumonia, which can lead to death, even if properly treated. The disease normally starts two to 10 days after the infection, with body aches, headaches and a cough. With the continuation of the illness come pains in the chest area, chills and a high fever. With severe infection the disease develops into a lung disease, which in around 15% of all cases leads to death.
Pontiac – fever, called after the city of Pontiac in the US State Michigan, has an incubation time 1 – 2 days, it is also caused by a legionella bacteria infection, and is not as severe as legionellosis. This disease normally involves head and body aches, as well as a cough and fever. It is an unpleasant illness but patients usually recover within five days.
How the Aquadron Addresses Legionella
The Aquadron treats all of the water that passes through the system, it does this by proportionally dosing all of the water with Anolyte, 24 hours a day, seven days a week. The Anolyte passes through the whole system, removing biofilm and killing bacteria, it even works in the shower heads and taps, at a point that is beyond the thermal mixing valves and that is not protected by thermal treatment. This ensures that Legionella colonies can not form in the pipework system.
Once the system has been disinfected it is possible to operate without the thermal barrier, this means that water temperatures can be reduced. This saves energy and money - the net effect is that you get improved water treatment with far higher levels of safety and energy savings pay for the system. Click here
for details of the potential cost savings. Click here
for more details on the Aquadron Legionella System. Click here
for project examples in hospitals and care homes.