Legionellosis is an infection caused by Legionella pneumophila bacteria. The disease can cause two different clinical conditions. It is important to note that both forms can occur in persons of any age, including those who have healthy immune systems.
The first is Legionnaire’s disease, which is a severe respiratory illness with pneumonia that may lead to hospitalization or death. Legionnaire’s disease most often affects middle-aged and older people who smoke or use tobacco containing products, have weakened immune systems or underlying medical conditions. Symptoms usually start about 2-10 days after exposure.