chancroid vs scabies

chancroid

noun
  • A sore characteristic of this infection. 

  • A sexually transmitted infection, caused by bacteria of species Haemophilus ducreyi, characterized by painful sores on the genitalia. 

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 chancroid and scabies occurred in a corpus of books? (source: Google Ngram Viewer )