E.R. is an infectious disease caused by human herpes virus 6 (HHV-6) or human herpes virus 7 (HHV-7), which is common in infants and young children and is characterized by fever for 3-5 days and rash after fever subsides. The incubation period is 7-17 days (average 10 days). The main symptoms are fever; sudden rise in temperature, up to 39-41 degrees, with fever lasting for 3-5 d and then falling. The rash; the main feature of the rash is a rose-colored, scattered maculopapular rash that recedes in 1-2 days, leaving no pigmentation and no flaking. The prognosis is generally good and no special treatment is needed. If the condition is serious and life-threatening, such as fulminant hepatitis, transplant-related disease, or HIV infection with HHV-6, the drugs ganciclovir and retinoic acid should be considered.