The book is divided into sixteen chapters. Being a Study in Biography, Which, After Twelve Preliminary Chapters Indispensable for the Preparation of the Lay Reader, Deals with the Life History of Typhus Fever, the proper “biography” of typhus occurs only in the last four chapters.
The first two thirds of the work provide background information on topics such as:
Scientific concepts and definitions (e.g. Chapter III: Leading up to the definition of bacteria and other parasites, and digressing briefly into the question of the origin of life, Chapter IV: On parasitism in general, and on the necessity of considering the changing nature of infectious diseases in the historical study of epidemics)
Diseases of the ancient world (chapter VI) and their effect on political and military history (chapters VII and VIII)
The important vectors of typhus mentioned in the title, rats and lice (chapters IX through XI)