Last revised by Joachim Feger on 25 Dec 2023

A zoonosis (plural: zoonoses), also known as a zoonotic disease, is an infectious disease in humans (the host) for which another vertebrate animal can be the vector. Some zoonoses have an additional vector besides the vertebrate e.g. R. rickettsii is carried by ticks on mammals. Viruses, bacteria, fungi or parasites can be zoonoses.

60% of cases of infectious disease are zoonotic in origin 1.

Zoonoses may be spread through direct or indirect contact with animals. Diseases that cannot exist without humans are not considered zoonotic by all sources (e.g. variant Creutzfeldt-Jakob disease), and neither are some diseases that may have begun as zoonoses but are predominantly transmitted by humans (e.g. HIV).

Examples of zoonotic diseases, with causative entities in brackets, include:

In Greek, the word ζώο (zoo) means animal and νοσος (nosos) means disease 2,3.

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