Zoonoses are diseases of animal origin that can affect people. The diseases may be caused by bacteria, parasites, protozoa, fungi and viruses.
Even if there is an infectious agent present, it does not always result in disease. Zoonoses depend on three factors; the infectious agent, a susceptible host and a way of spread.
Approximately 60-70% of emerging human infectious diseases are zoonoses and originate in domestic or wild animals.
More information can be found at Zoonoses - animal diseases that can infect people.