Introduction into Pathology of Ocular Zoonoses

Zoonosis: what does it mean? The meaning of the term “Zoonosis” has changed greatly over the time. At least in the first half of the 19th century, early microscopes easily identified fungi, small animals, protozoans and metazoans: bacteria and viruses were much too small to be visualized. Hence, for more than a century, the term zoonosis indicated any disorder due to infectious agents visible by microscope. Ironically, the first reports of cytomegaly were attributed to an infection by a novel fungal or amebic organism. However, with the advent of modern microbiolgy the understanding of zoonosis has changed completely. No later than 1958, the World Health Organization produced an official definition of Zoonosis as: “diseases transmitted in a natural way from vertebrate animals to humans”. Currently, three subtypes of Zoonoses may be distinguished: [1] 1. Zooanthroponoses: transmitted from vertebrates to humans. 2. Anthropozoonoses (rare): transmitted from humans to animals. 3. Geonoses/Sapronoses: diseases produced by animal-borne infectious agents, surviving in faeces, food, soil, or on plants, from there eventually affecting humans. This treatise on ocular Zoonoses will be divided into two main groups A and B, according to their respective way of transmission.