What describes a zoonotic disease?

• A. A disease that only affects animals
• B. A disease that is spread only by fleas
• C. A disease that cannot infect humans
• D. A disease that can be spread from animals to humans and from humans to animals

Answer: (D)

Zoonotic diseases are diseases that can move between animals and people. The defining feature is cross-species transmission, meaning the pathogen can jump from animals to humans and, in many cases, from humans back to animals as well. This bidirectional potential is what sets zoonoses apart from diseases that stay within one species.

So, the best description is a disease that can be spread from animals to humans and from humans to animals because it captures the idea of transmission across species. The other statements describe situations that aren’t about diseases shared between species: some affect only animals, some are tied to a specific transmission route like fleas, and some can’t infect humans at all. In practice, recognizing zoonoses helps you implement proper hygiene and protective measures to reduce cross-species transmission in settings like dog grooming.