Japanese encephalitis is caused by –
**Core Concept**
Japanese encephalitis is a viral infection of the central nervous system, primarily affecting the brain. It is a zoonotic disease, meaning it is transmitted between animals and humans. The causative agent is a flavivirus that replicates in the mosquito vector and then transmitted to humans through a bite.
**Why the Correct Answer is Right**
The correct answer is Japanese encephalitis virus (JEV), which is a single-stranded RNA virus belonging to the flavivirus family. JEV is primarily transmitted by the bite of an infected Culex mosquito, which is the main vector for the virus. The virus replicates in the mosquito's salivary glands and is then transmitted to humans through a bite. Upon entering the human body, the virus targets the central nervous system, where it can cause severe inflammation and damage to brain tissue.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because the correct answer is Japanese encephalitis virus (JEV), not the other flaviviruses like dengue or Zika virus.
* **Option B:** This is incorrect because Japanese encephalitis is not caused by a bacterium like Leptospira or E. coli.
* **Option C:** This is incorrect because Japanese encephalitis is not caused by a protozoan parasite like Plasmodium or Toxoplasma.
**Clinical Pearl / High-Yield Fact**
It's essential to note that Japanese encephalitis is a significant public health concern in many parts of Asia, particularly in rural areas where the disease is endemic. The risk of transmission is highest during the rainy season when mosquito populations are at their peak.
**Correct Answer:** C. Japanese encephalitis virus