<prompt> Define sustained fever?Fever is persistent and does not vary by more than 0.5degCdayFever is persistent and varies by more than 0.5degCday.Fever is persistent and does not vary by more than 1degCdayfever is persistent and varies by more than 1degCday.  <response>: Sustained fever is persistent and does not vary by more than 0.5degC 0.9degFday. Remittent fever is persistent and varies by more than 0.5degC 0.9degFday. Relapsing fever is characterized by febrile periods that are separated by intervals of normal temperature; teian fever occurs on the 1st and 3rd days malaria caused by Plasmodium vivax, and quaan fever occurs on the 1st and 4th days malaria caused by Plasmodium malariae.Ref: Nelson; 20th edition; Chapter 176; Fever; Page no: 1278 