scabies vs venereal disease

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. 

venereal disease

noun
  • Any of several contagious diseases, such as syphilis and gonorrhea, contracted through sexual intercourse. 

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