Legionella infection
Legionella bacteria can cause 2 illnesses in humans.
This includes:
- legionella pneumonia (legionnaires’ disease) which is a lung infection that is fatal
- a mild flu-like illness (Pontiac fever).
In the NT, there has been 29 reported cases of legionnaires’ disease over the last 5 years.
During this period, around 350 to 500 cases were notified nationally each year.
Where it's found
Legionella bacteria are found naturally in low levels in the environment.
There are several species of legionella, but the ones associated with human disease are legionella:
- pneumophila, which is found in :
- water cooling systems (cooling towers)
- warm water systems
- water heaters
- shower heads
- spa pools
- outdoor fountains
- longbeachae, which is found in potting mix or soils.
In the absence of effective maintenance and cleaning, high numbers of legionella pneumophila may be found.
How it spreads
The most common way a legionella infection is contracted is by breathing air contaminated with legionella bacteria.
Air is contaminated when aerosols (very fine droplets of water) containing legionella bacteria are released.
The aerosol needs to be very small so that it can penetrate deeply into the lung.
Evaporative cooling units that are used in home air conditioning units have not been known to cause a legionella infection.
A legionella infection is also not transmitted from person to person.
Who is at risk
Those at risk include:
- older people (aged over 50 years)
- people with chronic lung disease
- people with diseases that weaken the immune system such as diabetes and chronic kidney disease
- people who are taking medications which suppress the immune system, including corticosteroid tablets
- liver or kidney transplant patients and cancer patients
- smokers.
Symptoms
Non-specific ‘flu-like’ symptoms usually occur in the first 24 to 48 hours.
Legionnaires’ disease
Common symptoms of legionnaires’ disease include:
- high temperature (fever)
- stomach cramps and diarrhoea
- dry cough or a cough that may produce sputum
- shortness of breath
- aches and pains in the muscles
- chills
- feeling confused
- headache
- feeling tired and loss of appetite.
It can take 2 to 10 days for the symptoms to develop after inhaling legionella bacteria.
However, symptoms usually appear within 5 to 6 days.
Not all of the symptoms need to be present for diagnosis. People with these symptoms should see their doctor immediately.
Pontiac fever
The symptoms of Pontiac fever include:
- feeling tired and loss of appetite
- high temperature (fever)
- chills
- headache
- aches and pains in the muscles.
Pontiac fever does not present as pneumonia and has not been associated with death.
Symptoms appear 5 to 66 hours after exposure to legionella bacteria
They most often occur between 24 and 48 hours and resolve without treatment.
Diagnosis
To establish a diagnosis of a legionella infection, specialised laboratory tests must done using:
- blood
- urine or
- lung secretions (sputum).
Under the Notifiable Diseases Act 1981, legionnaires’ disease is a notifiable disease.
This means all cases are reported to the Centre for Disease Control.
Treatment
Legionnaires’ disease is treated with an antibiotic.
For those people with serious symptoms (such as severe difficulty in breathing), admission to hospital may be required.
People with Pontiac fever generally recover spontaneously within 2 to 5 days and antibiotic treatment is not required.
Prevention
Best practice guidelines include:
- regular treatment, cleaning, maintenance and monitoring of:
- water-cooling systems
- warm water systems and
- water storage units in line with national standards and work health and safety requirements
- avoiding direct inhalation of potting soil and wearing protective coverings over your nose and mouth
- washing your hands thoroughly after handling potting mix or soil, especially before eating or drinking.
An operation and maintenance manual should also be kept and readily accessible for water systems and units.
Information for health professionals
To find out more, go to the NT Health website.
Contact
Contact your nearest Centre for Disease Control on the NT Health website.