Legionnaires’ disease linked to Craigieburn area

Key messages

• The Department of Health is investigating an outbreak of Legionnaires’ disease in Craigieburn and the surrounding suburbs. Six cases have been notified as of 18 March 2026.
• People who have been in Craigieburn or the surrounding suburbs of Mickleham, Greenvale and Roxburgh Park from late February and who develop flu-like illness should seek urgent medical care.
• Healthcare professionals should be alert for Legionnaires’ disease in patients with flu-like symptoms, particularly those with atypical or severe pneumonia who have recently been in Craigieburn or the surrounding suburbs.
• If Legionnaires’ disease is suspected, request urinary antigen testing through your normal pathology provider. As a priority, order Legionella culture on sputum and serology on blood at symptom onset and 3 to 6 weeks later (as convalescent serology).
• Legionnaires’ disease is an urgent notifiable condition that requires notification to the Department of Health upon initial diagnosis or clinical suspicion as soon as practicable on 1300 651 160.

What is the issue?

The Department of Health has identified an outbreak of Legionnaires’ disease involving six cases who have spent time in Craigieburn and the surrounding suburbs. Cases had symptoms commencing in early March 2026 and have received treatment in hospital. Investigations are underway to identify the source of the outbreak through testing local cooling towers and other potential sources. The risk period for exposure is currently from late February onwards.

Legionnaires’ disease is caused by Legionella bacteria, which are widespread in the environment. They are found in natural bodies of water such as rivers, lakes, creeks and hot springs. They are also found in spas, warm water systems and artificial systems that use water for cooling, heating or industrial processes, such as cooling towers, as well as potting mix.

Legionnaires' disease is spread by breathing in fine droplets of water that contain the bacteria. It is not spread from person-to-person or by drinking contaminated water.

Who is at risk?

Although Legionella bacteria are commonly found in the environment, only a few people who come into contact with the bacteria become infected. People who are at greater risk include those who:

• are older (usually over 65 years of age)
• smoke
• drink excess alcohol
• have chronic lung disease
• have a weakened immune system
• have other underlying medical conditions such as diabetes, cancer or kidney failure.

Symptoms and transmission

Legionnaires’ disease often presents with initial flu-like symptoms such as headache, fever, chills, muscle aches and pains, and cough which may progress to an atypical chest infection, also known as atypical pneumonia. Other symptoms may include confusion and diarrhoea. Some people with Legionnaires’ disease may also develop kidney impairment.

A person may develop Legionnaires' disease by breathing in fine droplets of water that contain the bacteria. It cannot spread from person-to-person or by drinking contaminated water.

Recommendations

For the public

• If you live in, work in or have visited Craigieburn, or the surrounding suburbs of Mickleham, Greenvale or Roxburgh Park and develop flu-like symptoms, seek urgent medical care.

For clinicians

• Consider Legionnaires’ disease in patients presenting with compatible symptoms who live in, work in or have visited Craigieburn or the surrounding suburbs of Mickleham, Greenvale or Roxburgh Park.
• Consider testing in people with compatible symptoms who have travelled along the Hume Highway through the area and stopped for petrol or food in the area.
• If you suspect Legionnaires’ disease, request urinary antigen testing through your normal pathology provider. As a priority, order Legionella culture on sputum and serology on blood. Serology samples should be taken at symptom onset and 3 to 6 weeks later (as convalescence serology).
• Early diagnosis and treatment with appropriate antibiotics are important. Refer to the current edition of the Therapeutic Guidelines for treatment guidelines.
• Legionnaires’ disease is an urgent notifiable condition which requires notification to the Department of Health upon initial diagnosis or clinical suspicion as soon as practicable and within 24 hours.