Coyttarus, J.  De febre purpura epidemiali & contagiosa libri duo (1578).

Johannes Coyttarus (d.1590) was born in England, but practiced primarily in Poiters, France, where he eventually became dean of the faculty of the University of Poiters.  In what is a classic 16th century work on the classification of diseases, this work distinguishes petechial typhus from typhoid for the first time.

(Sources: Garrison & Morton; Biographisches Lexikon hervorragender Aertze)