chlamydia vs crab louse

chlamydia

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

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

crab louse

noun
  • A parasitic insect, Pthirus pubis, that lives amongst the pubic hairs of humans and feeds on blood. 

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