The louse shares with us the misfortune of being prey to the typhus virus. If lice can dread, the nightmare of their lives is the fear of someday inhabiting an infected rat or human being. For the host may survive but the ill-starred louse that sticks his haustellum through an infected skin and imbibes the loathsome virus with his nourishment is doomed beyond sucker. In 8 days he sickens, in 10 days he is in extremis, on the 11th or 12th day his tiny body turns red with blood extravasated from his bowel and he gives up his little ghost. Man is too prone to look upon all nature through egocentric eyes, to the louse we are the dreaded emissaries of death. He leads a relatively harmless life, the result of centuries of adaptations. Then out of the blue an epidemic occurs, his host sickens and the only world he has ever known becomes pestilential and deadly. And if as a result of circumstances not under his control his stricken body is transferred to another host whom he in turn infects, he does so without guile from the uncontrollable need for nourishment, with death already in his own entrails. If only for his fellowship with us in suffering, he should command a degree of sympathetic consideration.

— Rats, Lice and History by Hans Zinsser