Whether a cold or fever is caused by a virus or a bacterium can be identified from the following aspects: First of all, in terms of epidemiological characteristics, viral colds show an obvious clustering, with many people getting sick in a short period of time or several people in a family. Bacterial is sporadic, with few or no people around the patient having a cold or fever at the same time. Secondly, the clinical symptoms of viral cases are runny and clear nasal discharge with relatively mild symptoms in the throat. The bacterial ones show obvious redness, swelling and pain in the pharynx, and even complicate acute tonsillitis. The viral ones may also have symptoms such as diarrhea and conjunctival congestion. Lastly, laboratory tests can be used to identify the disease, which is more accurate. If the total white blood cell count is low or normal, it is considered to be viral, while if the total white blood cell count or neutrophils are significantly elevated, it is considered to be bacterial.