chancroid vs tabes dorsalis

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. 

tabes dorsalis

noun
  • neurosyphilis in the form of such degeneration. 

  • tabes of the back; a degeneration of the sensory neurons of the spinal cord carrying afferent information. 

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