Legionnaires' disease is a severe form of pneumonia caused by the bacterium Legionella pneumophila. This bacterium is commonly found in water sources, such as lakes and rivers, and can become a health concern when it grows and spreads in man-made water systems, such as cooling towers, hot tubs, and air conditioning systems. Legionnaires' disease is typically contracted by inhaling contaminated water droplets or mist. Symptoms of Legionnaires' disease can include high fever, cough, shortness of breath, muscle aches, and headaches. It can be particularly severe in older adults, smokers, and individuals with weakened immune systems. Research in this area focuses on understanding the sources and transmission of Legionella bacteria, improving diagnostic methods, developing effective treatment options, and implementing prevention strategies to reduce the risk of outbreaks. Recent studies have also explored the potential role of climate change in affecting the incidence and distribution of Legionnaires' disease.