elephantiasis vs syphilis

elephantiasis

noun
  • A complication of chronic filariasis, in which nematode worms block the lymphatic vessels, usually in the legs or scrotum, causing extreme enlargement of the infected area. 

syphilis

noun
  • A disease spread via sexual activity, caused by the bacterium Treponema pallidum. 

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