TEMPLATE QUESTION AND ANSWER SHEET
What is Legionnaires' disease?
Legionnaires' disease is a severe pneumonia caused by the
What are the symptoms?
The range of symptoms include a 'flu-like' illness with muscle
aches, tiredness, headache, loss of appetite, dry cough and fever, leading on to pneumonia.
Diarrhoea sometimes occurs and patients may suffer from confusion.
How serious is the disease and how common is it?
Legionnaires' disease is an uncommon but serious illness and
deaths may occur in approximately 10-15% of otherwise healthy individuals. The number of deaths
reported may be higher in some groups of patients, such as those who have weakened immune
Why is it called Legionnaires' disease?
An outbreak of this disease occurred in Philadelphia in 1976,
among people (Legionnaires) attending a state convention of the American Legion and led to
naming the disease after this group. Subsequently, the bacterium causing the illness was
identified and named Legionella pneumophila.
Is this a new disease?
No. Although the Legionella bacterium which causes the
disease was identified in 1976, cases have been confirmed as far back as 1947 and some probably
also occurred before then. However since 1976 further species of Legionella have been
identified in the environment such as Legionella longbeachae,
Legionella micdadei or Legionella bozemanii. A number of these
species can occasionally cause Legionnaires' disease.
Can I get the disease from other species of Legionella
such as Legionella longbeachae?
In Europe, Legionnaires' disease is most commonly, but not
exclusively caused by Legionella pneumophila. Other species, including
Legionella longbeachae, are common in the environment and can cause
Legionnaires' disease although such cases are only very rarely reported in Europe. The
occurrence of Legionnaires' disease cases caused by Legionella longbeachae
varies across the world and cases associated with this Legionella species are
more common in Australia, where they make up nearly half of the Australian cases of
How widespread is the disease?
Cases have been reported from all industrialised countries and
are increasing in most countries on an annual basis. Some 5000 cases are reported annually
across the EU and EEA/EFTA countries.
Where are Legionella bacteria found?
The bacteria are widely distributed in the environment and have
been found in rain water, puddles, ponds and rivers. Problems arise when they contaminate
man-made water systems, such as water in air conditioning cooling systems, hot and cold systems
in buildings, spa pools and other artificial water systems.
How is Legionnaires' disease acquired?
The infection is not contagious and cannot be caught from
another person. The disease is spread by aerosols (small water droplets that evaporate very quickly) from a contaminated water
system. Breathing in these contaminated aerosols or droplets is the usual route of
infection. Aspiration, where contaminated water gets into the lungs by mistake can be the source
of infection in some rare cases. These cases tend to be associated with infections acquired in
Who gets Legionnaires' disease?
All ages can be affected but it mainly affects people over the
age of 50 years. Men are three times more likely to get Legionnaires' disease than women.
Individuals with underlying medical conditions such as heart lung or liver disease - those with
impaired immune systems are also at greater risk from the disease. Smoking is also considered a
significant risk factor.
How soon do symptoms occur?
The incubation period can range from 2 to 14 days with a median
of 6 to 7 days after exposure.
What is the treatment?
There are specific antibiotics that are effective in treating
How is it diagnosed?
A rapid diagnosis can be made by testing a urine sample from the
patient, once the relevant symptoms have occurred.
What should I do if I think I have Legionnaires'
If you believe you have this infection, you should tell your
doctor so that the appropriate investigations can be started.
How is Legionnaires' disease prevented?
There are strict regulations to ensure that water systems used
for air cooling or for use in commercial, tourist and other buildings or settings are
maintained to standards that minimise risk from the disease and do not harbour the bacteria
that cause Legionnaires' disease.
Concerns have been raised about the link between compost and
Legionnaires' disease caused by Legionella longbeachae. The risk from exposure
to this species is likely to be very low for the healthy and younger population but there is
insufficient data to properly quantify the extent of the risk that compost and potting soils
may pose. Evidence from Australia suggests that avoiding inhalation of dust or moisture
droplets and good standards of personal hygiene when handling compost and soil may reduce the
risk of Legionnaires' disease.
What investigations are carried out on Legionnaires'
Public Health Departments collect information at the local and
national level on all reported cases. Trends or patterns of disease are studied which may show
clusters of cases linked to an area of residence or place of work. If an outbreak is detected,
local environmental health officers help identify the source of infection and control the
outbreak. Information about cases infected across Europe is channelled by Member States through
the European surveillance scheme ELDSNet coordinated by the European Centre for Disease Prevention and Control
based in Stockholm.