chancroid vs chlamydia

chancroid

noun
  • A sexually transmitted infection, caused by bacteria of species Haemophilus ducreyi, characterized by painful sores on the genitalia. 

  • A sore characteristic of this infection. 

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. 

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