Legionellosis

Legionellosis

Legionellosis is a notifiable disease.

Legionellosis results from infection by a group of bacteria named Legionella.

Many different species of Legionella are commonly found in the environment, some of which are known to cause illness in people. In Tasmania, legionellosis is mainly caused by Legionella pneumophila (Legionnaires’ disease) and Legionella longbeachae.

 

What are the symptoms?

Symptoms of legionellosis include fever, cough, breathlessness, chest pain and diarrhoea. Legionella generally infects the lung (pneumonia) which often results in severe illness.

Legionellosis is a disease of the middle-aged and elderly. Men are affected more frequently than women.

 

How is it diagnosed?

Legionellosis is usually diagnosed by a series of blood tests. Occasionally, the organism can be grown from a sample of sputum or lung fluid.

Legionella pneumophila infection may also be identified rapidly by testing a sample of urine.

 

 

Legionella pneumophila (Legionnaires' disease)

Legionella pneumophila are commonly found in water and have been isolated from hot water systems, air-conditioning cooling towers, hot and cold water taps and showers.

The bacteria must be inhaled to cause disease. Cigarette smoking, heavy alcohol use, other illness or stress increase the risk of this disease.

Incubation period: two to 10 days, usually five to six days.

Legionnaires' disease occurs most commonly in the warmer months.

Person-to-person spread does not occur. Exclusion from work is not necessary.

Legionella from natural sources can enter and colonise manufactured water systems such as water cooling systems incorporating cooling towers or evaporative condensers; airhouses, hot and warm water supply services; spa pools, spa baths and hydrotherapy pools; humidifiers and nebulisers and decorative fountains. Inhalation of aerosols generated by these systems can serve as a route of infection. These systems must be maintained according to national guidelines which reduce the risk of them growing Legionella and releasing them into the surrounding environment.

Antibiotic treatment prescribed by the attending doctor. Severe cases may need to be treated in hospital and may require intensive care.

Legionella longbeachae

Legionella longbeachae can be found in potting mixes, compost heaps and composted animal manures. Unlike other Legionellae it is not found in water.

How Legionella longbeachae are spread is uncertain. The bacteria may be breathed in or spread from hand to mouth. Legionella longbeachae can remain on hands contaminated by handling potting mix for periods of up to one hour. The bacteria can be readily removed from the hands by washing.

Incubation period: two to 10 days, usually five to six days.

Spread from person-to-person does not occur. Exclusion from work is not necessary.

To minimise the risk of infection when handling potting mix, gardeners should take the following precautions:

  • wear a face mask
  • open bag with care to avoid inhalation of airborne potting mix
  • moisten the contents to avoid creating dust
  • always wear gloves to avoid transferring the potting mix from hand to mouth
  • always wash hands after handling potting mix even if gloves had been worn.

These same measures should be adopted when handling other garden material such as compost.

Antibiotic treatment may be prescribed by the treating medical practitioner. Some cases may require admission to hospital.