Legionnaires Disease
Legionnaire’s disease is an uncommon form of pneumonia which occasionally occurs in holidaymakers. It is spread through aerosols of water containing the legionella germ, usually through poorly maintained cooling towers or air conditioning systems. It is treatable with antibiotics. There is no vaccine.
Legionnaires’ Disease and Holiday Accommodation
This information on Legionnaires ‘ disease is intended to explain what is meant by the ‘association’ of cases of legionnaires’ disease with an accommodation site.
Legionnaires’ disease is caused by infection with legionella bacteria. It is contracted from a water aerosol that is contaminated with legionella bacteria.
The sort of aerosol that allows transmission of legionella is found in ‘wet’ air conditioning systems, whirlpool spas and showers.
Legionella can grow in any water system that is not properly maintained. This means that if a source of infection is not detected and appropriately dealt with it can continue to infect people indefinitely. The time from infection to start of the illness (the incubation period) is between two and ten days.
The source of a person’s illness could often be one of many places since most people will come into regular contact with showers and air conditioning systems.
However if two or more cases are linked to the same site then it becomes more likely that this is the source of their infections. At this point samples of water may be taken from the site. If legionella are found in the water samples, and if appropriate samples are available from the cases these can be compared to see if they are the same. Microbiological tests can be carried out which can prove that the site was the source of a patient’s infection. However this is not possible in most cases.
This disease is of particular relevance for travellers since the clients at a hotel may come from many different countries.
The length of the incubation period means that many people who are infected while travelling will not become ill until after they return home. This can make it hard for the authorities in one country to locate the source of each case’s infection.
By pooling the data for a number of countries it is possible to identify accommodation sites that have been associated with more than one case. The authorities of the country in which the suspect site is can then be informed.
The European Surveillance Scheme for Travel Associated Legionnaires’ Disease has 31 participating countries.
The role of the scheme is to collect information on cases of legionnaires’ disease occurring in travellers so that sites associated with more than one case can be detected and the authorities in the relevant country informed.
Since the European Directive on Package Travel in 1992 the surveillance co-ordinator for England and Wales has informed the Association of British Travel Agents (ABTA) and the Federation of Tour Operators (FTO) of any English cases which are associated with accommodation likely to be used by tour operators.
The EWGLI collaborators in some other countries also pass information to their tour operators (Denmark, Netherlands, Sweden)
The following guidelines have been suggested as contributing to safe practice:
- Have one named person responsible for legionella control
- Keep hot water hot at all times - 50-60oC. It should be uncomfortable to the hands.
- Keep cold water cold at all times. It should be maintained at temperatures below 25
o C. - Run all taps and showers in guest rooms for a few minutes daily, even if the room is unoccupied.
- Keep showers, shower heads and taps clean and free from scale.
- Clean and disinfect cooling towers used in air conditioning systems regularly - every three months.
- Clean and disinfect heat exchangers (calorifiers) regularly - once a year.
- Disinfect the hot water system with high level (50ppm) chlorine for 2-4 hours after work on heat exchangers and before the beginning of every season.
- Clean and disinfect all water filters regularly -every one to three months.
- Inspect water storage tanks, cooling towers and visible pipe work monthly. Ensure that all coverings are intact and firmly in place.
- Ensure that system modifications or new installations do not create pipe work with intermittent or no water flow.
The European Working Group for Legionella Infections. http://www.ewgli.org
The European Working Group for Legionella infections was formed in 1986 by a group of epidemiologists and microbiologists who wished to promote collaborative work on legionellosis and its aetiological agents. This collaborative initiative led to the introduction of annual scientific meetings for EWGLI members and the establishment of a surveillance scheme to detect cases of Legionnaires’ disease in returning travellers. More recently, schemes for the standardisation of water sampling methods, legionella typing methods and the validation of urinary antigen detection as a diagnostic method have been introduced.
Legionnaires’ Disease (Legionellosis) FAQ
What is Legionnaires’ disease?
Legionnaires’ disease is a bacterial disease which may cause pneumonia. The majority of cases are reported as single (isolated) cases but outbreaks can occur.
Why is it called legionellosis?
An outbreak of this disease in Philadelphia in 1976, largely among people attending a state convention of the American Legion, led to the name Legionnaires’ disease. Subsequently, the bacterium causing the illness was identified and named Legionella pneumophila and the name of the illness was changed to legionellosis.
Is this a new disease?
No. While the bacterium was only recently identified, cases have been confirmed as far back as 1947 and cases probably occurred before that date.
How widespread is legionellosis?
It is a rare disease. In England and Wales 150-250 cases are reported each year. There were just over 4 cases per million people in Europe during 1998.
Where are legionellae organisms found?
Legionellae are widely distributed in the environment. They have been found in ponds, hot and cold water systems, and water in air conditioning cooling towers.
How is legionellosis spread?
The disease is spread through the air from a water source. To date, all studies have shown that person to person spread does not occur. Breathing in aerosols from contaminated water systems is the most likely route of transmission of infection. However, the circumstances in which this can happen appear to be very rare.
Who gets legionellosis?
All ages can get legionellosis but it mainly affects older adults. The early symptoms of legionellosis may be ‘flu-like’ with muscle aches, headaches, tiredness and a dry cough followed by a fever, chills and occasionally diarrhoea. Pneumonia may develop.
How soon do symptoms occur?
The incubation period ranges from 2 to 10 days but is usually 3 to 6 days.
What is the treatment?
Antibiotics are usually effective in treating the disease.
HTW has noted that amongst the submissions to the Committee on Toxicity (COT) it has been suggested that the symptoms highlighted by crew and passengers were akin to the condition of hyperventilation.
HTW has for many years received reports from concerned holiday makers or independent travellers as to the safety of their aircraft, ship or boat, train or road transport.
