Pseudorubella
Synonymous with Roseola infantum, a viral disease of infants sudden onset of high fever which lasts several and young children with days and then suddenly subsides leaving in its wake a fine red rash.
The causative agent is herpesvirus type 6 so the disease is known as Sixth Disease.
Also as Exanthem subitum (sudden rash), roseola, roseola infantilis.