Infectious diseases refer to diseases caused by pathogenic infections, and generally include both infectious and non-infectious categories. The treatment of infectious diseases is still mainly related to the pathogenic bacteria, if it is caused by bacterial infection, anti-infective treatment is needed. If it is caused by a viral infection, antiviral treatment may be required. Some viral infections are not treated with drugs, and symptomatic treatment is the main focus. If the infection is caused by a fungal infection, antifungal treatment is required. There are also some infectious diseases that are contagious, and for this group of patients, isolation treatment is needed to prevent cross-contamination to others.