Answer:
baseline, endemic (possibly hyperendemic) are all references to a constant number of infections
Step-by-step explanation:
What term describes a constant number of infections in a region?
Now, there are a few terms we could use for this.
Sometimes, it may be referred to as a baseline (because that's the level its typically at--the "constant" number)
Baseline also can be called "endemic" (the constant presence)
The -endemic really just means persistent, so "hyperendemic" is a persistent high-level, which could be the baseline for that region
epidemic/cluster/outbreak/pandemic are all when we variate strongly from the baseline/expected number of infections
hope this helps! have a lovely day :)