Zoonoses are diseases passed from animals to humans. The most recent high-profile example is swine flu. There are several dozen such diseases that affect humans. The Centers For Disease Control says:
Abstract
Microbiologic infections acquired from animals, known as zoonoses, pose a risk to public health. An estimated 60% of emerging human pathogens are zoonotic. [...]
Zoonoses: Diseases Passed From Animals To Humans