chlamydia vs syphilis

chlamydia

noun
  • Any of several common, often asymptomatic, sexually transmitted diseases caused by the microorganism Chlamydia trachomatis. 

  • Any of various coccoid microorganisms of the genus Chlamydia that are pathogenic to humans and other animals. 

syphilis

noun
  • A disease spread via sexual activity, caused by the bacterium Treponema pallidum. 

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