20 month old has had high fever for 4 days. is this normal for viral infection?

Define "high": I have some parents think 101 is a high temp while others don't until it hits 104. Any sustained (continuous) high fever over 102 suggests a bacterial infection not a virus. Viruses often reach 104 but cycle up & down over several days. By day 3-4 I expect it to be under 102 or check them. Some viruses maintain elevated temps for a week or more.