"And, of course, there is syphilis. Nietzsche's letters from 1867 until his breakdown provide a vivid account of the suffering of secondary syphilis. He complains of the pain, skin sores, weakness, and loss of vision that typify the repertoire of the disease. In his last year, his letters give evidence of euphoria"(Margulis 2024). https://www.amacad.org/publication/syphilis-nature-nietzsches-madness