**Core Concept**
Vector-borne diseases are illnesses transmitted to humans through the bite of infected arthropods, such as mosquitoes, ticks, and fleas. These diseases are a significant public health concern worldwide, with various vectors transmitting distinct pathogens.

**Why the Correct Answer is Right**
Brucella is a gram-negative, facultative intracellular bacterium that causes brucellosis. It is primarily transmitted through direct contact with infected animals or their products, such as unpasteurized milk and cheese, rather than through a vector. This bacterium does not rely on an arthropod vector for transmission, unlike the other options listed. Brucellosis is a zoonotic disease, meaning it can be transmitted between animals and humans, but the primary mode of transmission is not through a vector.

**Why Each Wrong Option is Incorrect**
**Option A:** Kyasanur Forest Disease (KFD) is a viral hemorrhagic fever transmitted through the bite of an infected tick, making it a vector-borne disease.
**Option B:** Japanese Encephalitis (JE) is a flavivirus transmitted through the bite of an infected mosquito, making it a vector-borne disease.
**Option D:** Plague is a bacterial disease caused by Yersinia pestis and can be transmitted through the bite of an infected flea, making it a vector-borne disease.

**Clinical Pearl / High-Yield Fact**
Vector-borne diseases are a significant public health concern, and understanding the vectors responsible for transmission is crucial for prevention and control measures. Awareness of the vectors involved can help healthcare professionals target specific interventions, such as insecticide use, vector control measures, and personal protective equipment.

**✓ Correct Answer: C. Brucella**