Webster's Revised Unabridged Dictionary · 1913

Recrudescence

Recrudescence (r?`kr?*d?s"sens) , noun

[Compare French recrudescence.]

1.
The state or condition of being recrudescent.
A recrudescence of barbarism may condemn it [land] to chronic poverty and waste. — Duke of Argyll
2.
(Medicine) Increased severity of a disease after temporary remission. — Dunglison

Also: Recrudescency