It is caused by human herpes virus type 6 or 7 infection. It is characterized by a sudden onset of high fever with no obvious aura and a tendency to have febrile convulsions within 24 hours of the onset of fever, with no other obvious accompanying symptoms. The patient’s body temperature drops after 3-5 days of repeated high fever, and a rose-red macular rash appears on the skin during the process of temperature reduction to normal or fever reduction. The rash is usually not painful or itchy and can be cured quickly if there are no other complications.