What really gets me is that the required dosage is really, really high. You've got to be pounding back G&Ts more or less non-stop – or your tonic has to be ridiculously powerful – for it to become a serious problem. (The FDA just recently issued new guidelines regarding the use of quinine to treat leg cramps in patients with renal failure. In other words, up until a few months ago it was regarded as the optimal treatment! So – even though it's now under review – it can't be THAT bad.)I suspect that what was happening was a feedback loop - at the first symptoms, the doctor and/or patient probably said "Aha! That nasty blackwater fever - we must increase the dosage!" That sort of misconception never ends well.