An unusual epidemic of Legionnaires’ disease has broken out in Melbourne.
As of Friday afternoon, the Victoria Department of Health confirmed 33 cases (with 10 suspected) of this severe and sometimes life-threatening lung disease. Most of those infected were hospitalized.
Investigations are ongoing during to determine the source of the epidemic.
Here’s what we know to date.
What is Legionnaires’ disease and the way does it spread?
Legionnaires’ disease is a bacterial infection attributable to inhaling contaminated water droplets. The water droplets have to be sufficiently small to be inhaled deep into the lungs to cause illness.
Disease isn’t being sent between people.
Legionnaires’ disease normally only affects individuals with weakened immune systems or health problems. People are with greater risk infections if:
- are over 40 years old
- they’re smokers
- you have chronic lung disease or existing respiratory conditions
- have a weakened immune system, e.g. transplant recipients
- produce other medical conditions similar to diabetes, heart or kidney disease.
Legionnaires’ disease normally causes severe pneumoniawhich is a chest infection with symptoms similar to cough, headache, fever, chills, and muscle aches.
Less common symptoms include nausea, vomiting, diarrhea, and disorientation. In extreme cases, Legionnaires’ disease can cause renal failure.
How is Legionnaires’ disease treated?
Early diagnosis and treatment It is vital to use appropriate antibiotics to prevent serious disease progression.
If no motion is taken or the improper antibiotic is prescribed, Legionnaires’ disease can lead to serious illness and the need for hospitalization.
GPs in Victoria at the moment are taking motion to ensure they don’t prescribe inappropriate antibiotics to people presenting with respiratory symptoms.
This is because it may possibly take several days for individuals with Legionellosis to realise after taking antibiotics that the drugs will not be effective – and this time is crucial for treatment.
What can we know about the epidemic in Melbourne?
The current epidemic in Melbourne is an example of this community-acquired disease.
Investigations are ongoing to determine the source. The large variety of cases in a brief time frame indicates a single source, probably some equipment releasing contaminated aerosols into the environment, normally outside the constructing. This style of outbreak is typically referred to as “explosive.”
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The more than likely cause is a cooling tower attached to the constructing. Most explosive outbreaks of Legionnaires’ disease are related to cooling towers.
Another indicator is the strain: the S1 subtype identified in Melbourne could be very different to Legionnaires’ disease attributable to potting mixes.
The Victorian government has advised all cooling tower operators to ensure they’re up to date with testing, servicing and auditing requirements. However, it isn’t unusual for the source to remain undetected.
The high density of cooling towers in a city like Melbourne makes identifying a single source extremely difficult.
How are bacteria released into the air?
It is unusual for such an outbreak to occur in the middle of winter. Legionnaires’ disease outbreaks related to cooling towers typically occur in late summer/fall when air-con systems are turned on after a chilly spell.
In winter, the biofilm (biological sludge) dies and doesn’t reproduce below 20°C. If the towers operate all 12 months round, they’ll reproduce all 12 months round.
Cooling towers are commonly used devices for recycling and evaporating water in buildings, especially in air-con systems. As a part of their operation, they have to release water into the environment. They release a considerable amount of aerosol into the air, even when operating optimally.
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This aerosol can travel considerable distances (kilometers) or more) from the source. If contaminated, there may be a risk of inhalation and illness.
Without good management, a cooling tower can act as an incubator for bacteria. The warm, nutrient-rich conditions inside cooling water systems are perfect for biological slimes (biofilms) to grow.
If sediment and sludge are disturbed – for instance, when the system is turned on after months of dormancy – a sudden aerosol “bloom” can occur in the aerosol.
The indisputable fact that the outbreak is happening in the winter suggests that the cooling towers are getting used to cool something aside from air-con, similar to computer or telephone systems. It is probably going that there was some disruption in the system that initiated the outbreak.
What should I do if I’m apprehensive?
Healthy people can inhale infected droplets and never develop into infected.
However, for individuals with weakened immune systems or damaged lungs, the disease might be serious.
The Victorian Department of Health advises individuals who experience symptoms to seek immediate medical attention in the event that they live in or have visited the Melbourne metropolitan area and surrounding areas. Symptoms may resemble the flu and include muscle aches, dry cough, fever and lack of appetite.