Health authorities in Melbourne and London are investigating significant outbreaks of Legionnaires' disease, a serious respiratory illness caused by Legionella bacteria found in warm water sources like cooling towers and air conditioning systems. In Melbourne, the outbreak has led to 60 confirmed and 10 suspected cases, resulting in one fatality and multiple hospitalizations, with a cooling tower in the Laverton North and Derrimut areas suspected as the source. Similarly, in London, 17 confirmed cases have led to 10 hospitalizations, with investigations focused on a specific neighborhood and workplace. Both outbreaks prompt urgent calls for medical vigilance, especially among those with symptoms of fever, cough, and pneumonia. The disease does not spread person-to-person and primarily affects older adults, immunocompromised individuals, and smokers. Health authorities are actively disinfecting suspected sources and continuing their investigations to precisely identify the contamination points.