Legionnaires' disease usually develops two to 10 days after exposure to legionella bacteria. It frequently begins with the following signs and symptoms: 
Headache
Muscle aches
Fever that may be 104 F (40 C) or higher
 By the second or third day, you'll develop other signs and symptoms that can include: 
Cough, which might bring up mucus and sometimes blood
Shortness of breath
Chest pain
Gastrointestinal symptoms, such as nausea, vomiting and diarrhea
Confusion or other mental changes
 Although Legionnaires' disease primarily affects the lungs, it occasionally can cause infections in wounds and in other parts of the body, including the heart. A mild form of Legionnaires' disease — known as Pontiac fever — can produce fever, chills, headache and muscle aches. Pontiac fever doesn't infect your lungs, and symptoms usually clear within two to five days.