Hans Zinsser is stalking a murderer. His quarry has terrified hapless victims for centuries, coming upon them suddenly, by stealth, with overwhelming power and agility, sending whole cities into panic, pushing empires to the edge of extinction, then vanishing, only to reappear thousands of miles away. Dr Zinsser’s story is not an ephemeral romance of vampire kitsch but a true tale of blood lust, life and death. Dr Zinsser is a bacteriologist. The murderer he hunts is typhus, an adversary he respects as Holmes respected Moriarty. So deep runs his feeling that after decades of struggle, he comes to love it ‘as Amy Lowell loved Keats’, and even to write its biography. His life is so intertwined with that of his enemy that his ‘biography of a bacillus’, Rats, Lice and History, may be read as a long and entertaining digression from his incomparable memoir, As I Remember Him: A Biography of RS, which he disguised as a third-person narrative, the RS of the title being his own Romantic Self.