chlamydia vs tabes dorsalis

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. 

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 chlamydia and tabes dorsalis occurred in a corpus of books? (source: Google Ngram Viewer )