Zoonotic pathogens are more than three times more likely to be associated with emerging diseases than non-zoonotic pathogens.

• A. True
• B. False
• C. Not determinable
• D. Sometimes true

Answer: (D)

The key idea is that diseases spilling over from animals are a major source of newly recognized human infections, so zoonotic pathogens are a leading cause of emerging diseases. However, the claim that they are more than three times as likely to be involved isn’t consistently supported across all data or definitions. Different analyses and time frames yield different magnitudes for how much more likely zoonotic pathogens are to drive emergence, and in some contexts the ratio isn’t that large. Because of this variability, the statement is not universally true—it's true in some situations but not in others.