Zoonotic diseases are a group of infectious diseases that are naturally transmitted between vertebrate animals and humans. The greatest risk for zoonotic disease transmission occurs at the human-animal interface through direct or indirect human exposure to animals, their products and/or their environments. In a study of 1415 pathogens known to affect humans, 61% were zoonotic.
In addition, a number of well known and preventable zoonoses continue to occur in many countries, especially in the developing world where they mostly affect the poorest segment of human society; some are transmissible to humans through food (brucellosis, tuberculosis), through bites from infected mammals (rabies) and insects (Rift Valley Fever) or via environmental contamination (echinococcosis/hydatidosis).