Dysentery is no joke: the defining symptom, blood in your stool, comes from your intestinal lining sloughing off. A good friend of mine got it in India and said the waves of pain whenever she had to defecate were worse than giving birth without anesthetics.

The one upside is that dysentery is common enough in India that it was promptly recognized and treated, with a single giant horse pill targeting both bacillary & amoebic dysentery that basically cured her in 24 hours.