Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Legionnaires' Disease ?
    ### Response:
    Legionnaires' disease is a type of pneumonia caused by bacteria. You usually get it by breathing in mist from water that contains the bacteria. The mist may come from hot tubs, showers, or air-conditioning units for large buildings. The bacteria don't spread from person to person.
    