 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
Background |
|
|
|
Legionnaires'
disease is an uncommon form of pneumonia that may have serious
consequences for some people, especially people in the older
age groups. The bacterium responsible for legionnaires’
disease was identified in 1976 after a large outbreak at
a hotel in Philadelphia, USA. The disease got its name from
the group of people affected in this outbreak. They were
retired American service personnel who were attending a
legion convention. Since the outbreak in 1976, cases and
outbreaks have been reported from all countries in Europe,
many of them linked to hotels and other types of holiday
accommodation. |
|
| |
|
|
|
|
|
|
What
is legionnaires' disease? |
|
|
|
Legionnaires'
disease is an uncommon form of pneumonia. The disease has
no particular clinical features that clearly distinguish
it from other types of pneumonia, and laboratory investigations
must be carried out to confirm the diagnosis. It normally
takes between 2-10 days to develop symptoms (typically five
to six days but very rarely some cases may take two to three
weeks to develop symptoms). Patients usually start with
a dry cough, fever, headache and sometimes diarrhoea and
many people go on to get pneumonia. People over the age
of 50 are more at risk than younger people, and males are
more at risk than females. Effective antibiotic treatment
is available if the diagnosis is made early in the illness.
Deaths occur in about 5-15% of travellers who get the disease,
depending on their age and individual health status. Smokers
are more at risk than non-smokers. |
|
| |
|
|
|
|
|
|
How
do you get legionnaires' disease? |
|
|
|
People
become infected when they breathe in air that contains tiny
droplets of water known as aerosols, inside of which are
the legionella bacteria. If the bacteria get inhaled into
the lungs they can cause infection. Legionnaires’
disease cannot be got from water you drink that enters your
stomach in the normal way – the bacterium has to get
into the lungs through breathing it in. The illness is not
spread from person to person. |
|
| |
|
|
|
|
|
|
Where
do the legionella bacteria come from? |
|
|
|
Legionella
bacteria are common and can be found naturally in environmental
water sources such as rivers, lakes and reservoirs, usually
in low numbers. If the bacteria get into water systems used
in buildings such as hotels, they can sometimes cause a
risk to humans if people get exposed to them through air
conditioning or air cooling systems, or through contaminated
water systems used for baths or showers etc. |
|
| |
|
|
|
|
|
|
How
do outbreaks occur? |
|
|
|
Experience
shows that outbreaks in hotels are mostly associated with
hot or cold water distribution systems. If the bacteria
is in the water in quantities that can cause infection,
someone taking a shower would inhale the bacteria trapped
inside the tiny aerosols that are created when the shower
water hits the hard surfaces of the shower unit or bath.
They may also be affected by other water systems that cause
aerosols, for example whirlpool spas and fountains. In contrast,
large explosive outbreaks in the community are mostly associated
with cooling towers. Cooling towers are devices used to
cool buildings. They are also called “wet air conditioning
systems” because the process of cooling air involves
extensive contact between water and air, thereby creating
aerosols. When the legionella bacteria are present in these
systems they can cause legionnaires’ disease. Air
conditioning units that use water to cool the air can also
pose a risk in hotels. However, many air conditioning systems
are “dry” and these pose no risk for legionnaires’
disease. |
|
|
|
When
an outbreak of legionnaires' disease occurs, the source
may be found through two types of investigation. One collects
information on the activities and whereabouts of the patients
with legionnaires' disease to look for links between cases
such as staying at or visiting the same places before they
became ill. The other involves looking for the legionella
bacteria in the suspected water sources and in clinical
specimens from the patients. If the bacteria are found in
both, specialised laboratory methods are used to see if
they are of the same type. |
|
|
|
