Swimming in some lakes with still water can lead to infection with Legionella -- a bacterium that can cause pneumonia -- said a team of researchers on Tuesday calling out on people who engage in open water swimming to be aware of the risk.  

Also referred to as legionnaires' disease, infection with legionella causes severe lung inflammation that is characterised by fever, chills, malaise, chest pain, cough, fatigue, respiratory symptoms, and sometimes diarrhoea.