In routine blood tests, if the white blood cell count is normal or decreasing with an increase in lymphocyte count, a viral infection is considered. This is not entirely absolute, as there are some diseases that are viral infections that may also show a significant increase in white blood cell count, such as infectious mononucleosis, epidemic hemorrhagic fever, and other such diseases. In addition to routine blood tests to determine whether the infection is bacterial or viral, a comprehensive analysis should be made based on the patient’s clinical symptoms, and if necessary, C-reactive protein and calcitoninogen tests should be completed. Most of the patients can be treated after the basic judgment after such index examination.