More than a hundred years of parasitic zoonoses: with special reference to trichinosis and hydatid disease

The zoonoses provide common ground for the medical and veterinary professions to study infections which are shared by man and animals, and since parasitic zoonoses formed the basis of the earliest experimental studies in comparative pathology, it is proposed to illustrate the historical aspects of the zoonoses mainly by reference to parasitic diseases, and particularly those where ideas on the biology of the parasites, their life cycles, and their ecology have changed dramatically during the past 100 years. To begin with, it is necessary to define what is meant by the term zoonosis and to illustrate the way in which the zoonoses have evolved. This is the subject of Part I of this paper. Part II and Part III outline the early discoveries relating to the life cycles of two important zoonoses, namely, hydatid disease and trichinosis and illustrate some of the more recent advances in knowledge of their epidemiology.