Differences in viral and bacterial infections are often difficult to recognize because they can cause similar symptoms. Even so, viral and bacterial infections are basically very different. In some types of diseases, it is difficult to determine the difference between viral and bacterial infections as the cause. For example diarrhea, meningitis and pneumonia which can be caused by both. The doctor can do a physical examination and medical history. If necessary, the doctor can also ask for additional tests such as a urine test, blood test or culture test to confirm a viral or bacterial infection. What is a Virus Infection? Viruses are microbes of very small size. They live and multiply by sticking to the host cell. When the virus enters the body, they will attack the cells in the host body, control the cells, and continue to multiply in the cell. Viruses can damage, kill, change cells in the body, for example in the liver, blood, or respiratory tract. Viruses can also trigger a d...