epidemic vs upsurge

epidemic

noun
  • An occurrence of a disease or disorder in a population at a frequency higher than that expected in a given time period; an episode of outbreak and subsequent high prevalence. 

  • A widespread disease that affects many individuals in a population. 

  • The spreading of an idea or belief amongst a population. 

adj
  • Like or having to do with an epidemic; widespread. 

upsurge

noun
  • A sudden strong rise or flow. 

verb
  • to surge up, or to become stronger or greater 

How often have the words epidemic and upsurge occurred in a corpus of books? (source: Google Ngram Viewer )