Brihat Parashara Hora Shastra
पिट्कादिर्भवेत् तस्य तदा रोगो न संशयः । ग्रहणी जलरोगो वा तत्र केतौ स्थिते सति ॥ ८१॥
If Ketu is in the 4th, or the 5th, one will suffer from dysentery and afflictions, due to (impure) water.
english translation
piTkAdirbhavet tasya tadA rogo na saMzayaH । grahaNI jalarogo vA tatra ketau sthite sati ॥ 81॥
hk transliteration by Sanscript