Arthashastra
न च अकामः पुरुषः कुष्ठिनीम् उन्मत्तां वा गच्छेत् ॥
If a man has no inclination, he may not lie with his wife who is either afflicted with leprosy or is a lunatic.
english translation
na ca akAmaH puruSaH kuSThinIm unmattAM vA gacchet ॥
hk transliteration by Sanscript