crab louse vs herpes

crab louse

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

herpes

noun
  • A viral infection, caused by Human alphaherpesvirus 1 and Human alphaherpesvirus 2, marked by painful, watery blisters in the skin or mucous membranes or on the genitals. 

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