Which statement best defines zoonotic diseases?

Which statement best defines zoonotic diseases?

• A. They affect only animals
• B. They affect only humans
• C. They can be transmitted between animals and humans
• D. They cannot be transmitted by vectors

Answer: (C)

Zoonotic diseases are infections that can pass between animals and humans. This cross-species transmission is the defining feature, meaning the disease can move from animals to people and, in some cases, from people back to animals. Transmission can occur through direct contact with an infected animal, contact with contaminated animal products or environments, or via vectors like ticks or fleas, depending on the pathogen. Because of this shared potential between species, the statement that best defines zoonotic diseases is that they can be transmitted between animals and humans. The other ideas—affecting only animals, affecting only humans, or being impossible to transmit by vectors—don’t fit, since many zoonoses do involve cross-species transmission and can be vectored or occur without vectors.

Zoonotic diseases are infections that can pass between animals and humans. This cross-species transmission is the defining feature, meaning the disease can move from animals to people and, in some cases, from people back to animals. Transmission can occur through direct contact with an infected animal, contact with contaminated animal products or environments, or via vectors like ticks or fleas, depending on the pathogen. Because of this shared potential between species, the statement that best defines zoonotic diseases is that they can be transmitted between animals and humans. The other ideas—affecting only animals, affecting only humans, or being impossible to transmit by vectors—don’t fit, since many zoonoses do involve cross-species transmission and can be vectored or occur without vectors.