How to differentiate between influenza A and influenza B

In clinical medicine, "Type A flu" and "Type B flu" are terms used to distinguish between two different infectious diseases based on their epidemic periods and characteristics. Type A flu refers to influenza, which typically presents symptoms such as elevated body temperature, fever, and cough within one to two days, and these symptoms usually last for several days. Type B flu refers to epidemic parotitis (mumps), whose main symptoms include nasal congestion, runny nose, and headache. It does not involve fever; mild cases generally recover within three to four days, while severe cases may last one to two weeks. In summary, the hallmark of Type A flu is the presence of fever, whereas Type B flu is characterized by the absence of fever but the presence of typical nasal congestion.