Just as the only reservoir for the typhus virus in nature is provided by man, so the only vector of infection is the louse. The bite of the louse is not virulent immediately after the infecting meal. It becomes so only towards the 7th day following infection.
Archives Militaires du Ier Siecle. Texte Inedit de Papyrus Latin du Geneve No. 1, Publie Sous Les Auspices de la Socete Academique de Geneve, Avec Fac-simile, Description et Commentaire