Zoonotic Diseases — MCQs

Question 51: Which disease does not have a known animal reservoir?

• A. Brucella melitensis
• B. Francisella tularensis
• C. Bordetella pertussis (Correct Answer)
• D. Pasteurella multocida

Explanation: ***Bordetella pertussis*** - **Bordetella pertussis**, the causative agent of whooping cough, is unique among these options as it has **no known animal reservoir**. It is exclusively a human pathogen. - Transmission occurs directly from person to person via respiratory droplets, highlighting its **anthroponotic** nature. *Brucella melitensis* - **Brucella melitensis** is primarily associated with **goats and sheep**, acting as a significant animal reservoir. - Humans typically acquire brucellosis through contact with infected animals or consumption of unpasteurized dairy products. *Pasteurella multocida* - **Pasteurella multocida** is a common commensal bacterium found in the oral flora of various animals, including **cats and dogs**. - Human infections usually result from **animal bites or scratches**, demonstrating clear zoonotic transmission. *Francisella tularensis* - **Francisella tularensis**, which causes **tularemia**, has numerous animal reservoirs, including **rabbits, rodents, and ticks**. - Humans can contract tularemia through direct contact with infected animals, insect bites, or inhalation of contaminated aerosols.