Final answer:
A comprehensive blood test is usually ordered to diagnose someone with a fever of unknown origin.
Step-by-step explanation:
The type of test that is usually ordered to help diagnose someone with a fever of unknown origin is called a comprehensive blood test. This test is done to evaluate various parameters such as complete blood count, liver function, kidney function, inflammatory markers, and infectious disease markers. By analyzing these results, doctors can narrow down the potential causes of the fever and determine the appropriate treatment.