Final answer:
A fluctuating fever that returns to or below baseline and then increases again is known as a relapsing fever. In diseases such as louse- and tickborne relapsing fevers, the fever typically starts with a sudden high temperature, accompanied by headache and muscle aches. This pattern may repeat several times unless treated with antibiotics.
Step-by-step explanation:
A fluctuating fever that returns to or below baseline and then increases again is known as a relapsing fever.
In diseases such as louse- and tickborne relapsing fevers, the fever typically starts with a sudden high temperature, accompanied by headache and muscle aches. After about 3 days, these symptoms subside, only to return again after about a week. This pattern may repeat several times unless treated with antibiotics.
The cyclical nature of the symptoms in relapsing fevers is due to bacterial antigenic variation and immune evasion.