The Ganges may have been sacred to one of the world's largest religions, but to me, the doctor, it was notable as one of the world's most polluted rivers, thanks in part to all the incompletely cremated bodies that had been thrown into it. Knowing I'd be taking those little sips of river water, I looked up the bacterial counts on a website beforehand and premedicated with appropriate antibiotics. Even so, I developed a Giardia infection, having forgotten to consider the possibility of parasites.