The last time I came down with malaria they dosed me with bitter white tablets the size of elephant tranquillisers. The drug turned my skin yellow. I developed severe tinnitus, so that for a fortnight I felt as if I’d just emerged from a heavy-metal concert. And I got so depressed all I wanted to do was crawl into a dark place and die. I didn’t, thanks to those whopping tablets of quinine sulphate.