Pneumonic plague is spread by:
**Core Concept**
The pneumonic plague is a severe form of infection caused by the **_Yersinia pestis_** bacterium. It primarily affects the lungs and can be transmitted between humans. Understanding the mode of transmission is crucial for preventing outbreaks.
**Why the Correct Answer is Right**
Pneumonic plague is spread through respiratory droplets when an infected person coughs, sneezes, or talks, releasing droplets that contain the **_Yersinia pestis_** bacteria. This can be inhaled by another person, leading to infection. The correct answer should highlight this direct person-to-person transmission route.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not involve direct person-to-person transmission.
**Option B:** Incorrect as it is not the primary mode of pneumonic plague transmission.
**Option C:** Incorrect because, while fleas can transmit the bubonic form of the plague, they are not the primary vectors for pneumonic plague.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that pneumonic plague can be highly contagious and deadly if not treated promptly. Early symptoms include **fever**, **chills**, and **cough**.
**Correct Answer:** D. Respiratory droplets from person to person.