crab louse vs scabies

crab louse

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

scabies

noun
  • An infestation of parasitic mites, Sarcoptes scabiei, causing intense itching caused by the mites burrowing into the skin of humans and other animals. It is easily transmissible from human to human; secondary skin infection may occur. 

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