be sick of a fever

Concise Bible Dictionary:

The words in the originals imply “a burning heat,” so that there is no doubt that what is commonly known as “fever” is intended (Deut. 28:22; Matt. 8:14-15; Luke 4:38-39; John 4:52; Acts 28:8). The same Hebrew word is translated BURNING AGUE in Leviticus 26:16.

Strong’s Dictionary of Greek Words:

Greek:
πυρέσσω
Transliteration:
puresso
Phonic:
poo-res’-so
Meaning:
from 4443; to be on fire, i.e. (specially), to have a fever
KJV Usage:
be sick of a fever