Vector for plague is-
**Core Concept**
The plague, also known as the Black Death, is a zoonotic disease caused by the bacterium *Yersinia pestis*. The disease is transmitted to humans through the bites of infected fleas, which live on rodents and other small mammals.
**Why the Correct Answer is Right**
The correct answer is *Yersinia pestis*. The bacterium *Yersinia pestis* is a Gram-negative, rod-shaped bacterium that is transmitted to humans through the bites of infected fleas. The fleas become infected by feeding on the blood of rodents and other small mammals that are infected with the bacterium. When an infected flea bites a human, it regurgitates the bacteria into the wound, causing infection. The bacteria then multiply and cause the characteristic symptoms of plague, which include fever, headache, and swollen lymph nodes.
**Why Each Wrong Option is Incorrect**
* **Option A:** is incorrect because it is not a known vector for plague.
* **Option B:** is incorrect because it is not a bacterium that causes plague.
* **Option D:** is incorrect because it is not a known vector for plague.
**Clinical Pearl / High-Yield Fact**
It's essential to recognize that the plague is a zoonotic disease, meaning it can be transmitted from animals to humans. Fleas are the primary vectors for the disease, and rodents and other small mammals are the primary reservoirs. This knowledge is crucial for public health officials and medical professionals to prevent and treat the disease.
**Correct Answer: C. Yersinia pestis.**