flare-up vs recrudescence

flare-up

noun
  • A sudden intensification in activity. 

  • An inflammation such as of tendons (tendonitis) or joints (osteoarthritis). 

  • A sudden outbreak, outburst or eruption (originally of flame, but now used more generally of any violent activity or emotion). 

recrudescence

noun
  • The acute recurrence of a disease, or its symptoms, after a period of improvement. 

  • The condition or state being recrudescent; the condition of something (often undesirable) breaking out again, or re-emerging after temporary abatement or suppression. 

  • The production of a fresh shoot from a ripened spike. 

How often have the words flare-up and recrudescence occurred in a corpus of books? (source: Google Ngram Viewer )