Transmission electron micrograph (TEM) created from a whole preparation of Legionella pneumophila bacteria that had been negatively stained using uranyl acetate, and grown on bacteriologic medium, reveals L. pneumophila organisms reproducing, undergoing the process of cell division, as well as delineating the bacterium's outer envelope. Legionnaires' disease can have symptoms like many other forms of pneumonia, so it can be hard to diagnose at first. Signs of Legionnaires' disease can include: cough, shortness of breath, high fever, muscle aches and headaches. These symptoms usually begin 2 to 14 days after being exposed to the bacteria. Magnification @ 43,700x.