Q fever

Q fever is an acute febrile illness caused by the bacterium coxiella burnetii.

It is present in all countries except New Zealand.

In Australia, the disease is present in all jurisdictions including the Northern Territory (NT).

Although, it is more commonly found in northern New South Wales and Queensland.

How it is spread

The bacteria are most commonly carried by cattle, sheep and goats.

It may also be carried by a wide variety of other species of livestock, domesticated pets and wild animals.

Infection in humans usually occurs by inhalation of the bacteria contained in fine aerosol particles from infected animals shed in:

• placental tissue and
• amniotic fluid, blood, milk, urine or faeces.

Humans can also be infected indirectly by exposure to contaminated dust in the environment, which may be a long way from the original source.

These organisms can survive in the environment for a long period of time as they are resistant to heat, drying and common disinfectants.

Less commonly Q fever may be caused by drinking unpasteurised infected milk, bites from infected ticks or through cuts or skin wounds from contaminated equipment or environment.

Human to human transmission is not thought to occur.

Incubation

Symptoms occur 2 to 4 weeks after infection occurs.

Symptoms

Infected animals are often well and may show no signs of the disease.

About 50% of people with Q fever will also have no symptoms at all. Others may develop a brief and mild illness.

Q fever can however present with an acute severe influenza-like illness, commonly resulting in infection of lungs or liver.

Patients may develop one or more of the following symptoms:

• sudden onset of acute fever greater than 39ºC (usually lasts 1 to 2 weeks)
• chills or rigors
• profuse sweating
• non-productive cough
• chest pain
• severe headache
• photophobia
• confusion
• muscle pain
• fatigue
• nausea / vomiting / loss of appetite
• diarrhoea
• jaundice
• rash.

Death from acute Q fever is rare.

In 1% to 5%, Q fever may persist and cause chronic infection. Most commonly this affects the heart valves, particularly if there is already underlying valve damage, and can lead to heart failure. Chronic bone infection can also occur.

Sometimes the only symptom is fever lasting for more than a week. So it is important to make your doctor aware of any potential animal exposure so that Q fever can be considered.

Up to 20% of those infected develop a post Q fever fatigue syndrome.

Who is at risk

Occupational groups most commonly at risk include:

• abattoir workers
• meat processing workers
• livestock workers
• veterinarians and veterinary nurses
• people visiting stockyards or those coming in contact with infected animal secretions and products of conception.

Treatment

Antibiotic treatment, usually doxycycline is the most effective treatment for acute Q fever.

It is given within 3 days of onset and continues for 14 to 21 days.

Further treatment may be needed in chronic Q fever or if there are complications.

Prevention

• Be aware and cautious of the sources of infection
• Shower after working in at-risk settings and wash clothes as infected particles may be carried on clothing
• Appropriately dispose of birth products from any animals that come in contact with humans
• Do not consume unpasteurised milk products

Vaccinations

Vaccinations are available for those at increased risk of Q fever.

To avoid reactions to the vaccine, a screening pre-vaccination skin test and a blood test are performed.

Check with your GP. See list of vaccine and test providers below.

Information for health professionals

To find out more, go to the NT Health website.

Contact

For more information, contact your nearest Centre for Disease Control.