An estimated 8,000 to 18,000 people get Legionnaires' disease in the United States each year. Some people can be infected with Legionella bacteria and have mild symptoms or no illness at all. Patients with Legionnaires' disease usually have fever, chills, and a cough, which may be dry or may produce sputum. Some patients also have muscle aches, headache, tiredness, loss of appetite, and, occasionally, diarrhea. From the time of infection with Legionella bacteria, it takes 2-10 days for symptoms to appear. In most cases, symptoms begin after 5-6 days. Legionnaires' disease is treated with antibiotics, such as erythromycin. The earlier that treatment is begun, the better the outcome.

　　The first known outbreak of Legionnaires' disease was in Philadelphia, USA, in 1976. A total of 221 people contracted the disease and 34 died. Most of those that died were Legionnaires and that's how the disease got its name. The second largest outbreak was at the Stafford hospital in England in 1985; a total of 101 people contracted the disease and 28 died.

　　军团病是一种非常严重的、有时可以致命的肺炎。军团病是由军团杆菌引起，这种细菌产生在自然环境中，在温水里及潮热的地方蔓延。人工供水系统有时也能为军团杆菌的大量繁殖提供生存环境。这些系统包括淋浴器、矿泉池、喷泉以及空调设备的冷却水塔。人们通常是由于呼吸了被军团杆菌污染的水源散发的水雾而传染上军团病的。

　　据估计，在美国每年都有国每年都有8000~18000人感染上军团病。有些军团病感染者所表现出来的症状比较温和，甚至根本就没有得病的迹象。军团病患者通常有发烧、畏寒及干咳或咳痰等表现。部分患者还有肌肉疼痛、头痛、疲劳、食欲不振及偶尔腹泻等症状。这种病的潜伏期约为的潜天。许多病例表明，出现症状需要状需要5~6天的时间。军团病可以用红霉素等抗生素进行治疗，越早治疗效果越好。

　　军团病已知的首次爆发是在发是1976年美国费城，221人感染疾病，其中死亡34人。由于大多的死者都是军团成员，因此称为军团病。该病的第二次大爆发是1985年在英国的斯塔福德医院。这次101个被感染者中有28人死亡。