Legionella symptomen

Do you always run your taps when returning home from holidays? Many people are aware that Legionella can multiply rapidly in warm and stagnant water. Yet, since 2013 the number of reported Legionnaires’ disease cases has increased by 58% and this percentage is increasing exponentially.¹ How do we get infected, what are the Legionella symptoms, and what can you do to prevent it?

How can you get infected?

The Legionella bacteria can make us sick if we breathe-in small aerosolized water droplets containing the bacterium.² This happens when water vapor is inhaled or when we choke on water and the bacterium ends up in our lungs.² Causes are often found to be garden hoses, showers, fountains or high-pressure sprayers. Hot tubs, treatment plants, cooling towers that cool buildings or industrial processes can also cause Legionella aerosolization.

We can’t get sick by drinking infected water. Also, the disease is not contagious. Want to know more about how an infection takes place? Read our blog the Legionella infection route.

Incubation period Legionellosis

The incubation period of legionellosis lasts 2 to 19 days (usually 5 to 6 days).³ During this period you are infected but you do not show any Legionella symptoms.

Legionella symptoms and disease progression

Legionella disease has two forms: a light form and a heavy form. The light form is also known as the Legionella flu or Pontiac Fever. The heavy form is called Legionella pneumonia, or the ‘veteran disease’ which is named after an epidemic in Philadelphia (US) where veterans became infected with the Legionella bacteria. 

Legionella flu

When infected with the light form of Legionella flu, also known as Pontiac Fever, you will experience typical flu symptoms. The headache, fever, cough, and muscle pain often resolve within 2 to 5 days. You may not even realize that you had the Legionella flu. 

Veteran disease

The heavy form of Legionella, called Legionella pneumonia but better known as the veteran disease, often goes hand in hand with a severe pneumonia. The other Legionella symptoms that occur are a strong headache, cough, fever (> 39 degrees), shortness of breath, vomiting, diarrhea, and confusion. There is a risk of dying from this form of Legionella. Therefore, a doctor should be consulted on time. When dealt with timely, the symptoms can be treated with antibiotics. Within a few weeks you could be up and running again.

Risk groups

People with reduced resistance are more susceptible to a Legionella infection: elderly, young children, and smokers. Around 80% of Legionella cases are 50 years or older and men are three times as likely to get sick.

Preventative measures at home

Bacterial hotspots close to home are found in saunas, showers, steam baths, air conditioning, fountains, whirlpools and swimming pools. Keep an eye out to unused faucets and do not leave garden hoses, watering cans, and plant sprayers in the sun. This reduces the risks of aerosolization of contaminated water. Returning home from vacation? Place a bucket under your taps and let it run for at least 1 minute. Leaving you with fresh water from the tap and a full bucket to water the plants. 

Preventative measures for companies

During the hot summers it is very important to provide extra protection for your guests and employees. Higher temperatures can cause the traditional control method (thermal management) to be insufficient. Also, forms of chlorination are becoming less or ineffective. In practice, it is becoming increasingly difficult to keep cold water pipes cold, by which the risk of Legionella growth increases. The solution for this is copper silver ionization. This Legionella control technique is not temperature dependent and is effective throughout the entire drinking water installation. As a result, the entire Legionella contamination is addressed and your guests and employees can enjoy fresh water without worry.


  1. https://ecdc.europa.eu/sites/portal/files/documents/AER_for_2017-Legionnaires-disease_1.pdf
  2.  https://www.rivm.nl/legionella 
  3.  https://lci.rivm.nl/richtlijnen/legionellose
  4. https://www.nationalacademic.nl/nieuws/legionella-symptomen-herkent-u-ze 
  5. Van Kenhove, E. (2018). Coupled Thermohydraulic and Biologic Modelling of Legionella Pneumophila Proliferation in Domestic Hot Water Systems (Doctoral dissertation, Ghent University).
  6. https://www.strooming.nl/legionella/blog/ziekteverloop-legionella/