Reviewed by Chris NancollasPICADOR, 336pp, £16.99Tablet bookshop price £15.30            Tel 01420 592974Hans Christian Andersen was so frightened of being buried alive that he never went to sleep without leaving a note on his bed to assure anyone who might think he had died that “Jeg er skindød”, or “I only seem to be dead”. Then there is the case of the Ethiopian schoolgirl who was unable to stop herself eating the wall of her home in Addis Ababa. For the science journalist David Adam, the obsession was an unshakeable, crippling fear that he had contracted Aids. “I see HIV everywhere. It lurks on toothbrushes and towels, taps and telephones …” The Man Who Couldn’t S