Agent in KFD –
**Core Concept**
KFD, or Kyasanur Forest Disease, is a tick-borne viral hemorrhagic fever caused by the Kyasanur Forest Disease virus (KFDV). The disease is transmitted to humans through the bite of an infected tick, particularly the genus *Hyalomma* and *Rhipicephalus*. The virus affects the hematopoietic and nervous systems, leading to symptoms such as fever, headache, and hemorrhaging.
**Why the Correct Answer is Right**
The correct answer is the flavivirus, which is a single-stranded RNA virus belonging to the Flaviviridae family. KFDV is a member of this family, which also includes other tick-borne viruses such as the Powassan virus and the Tick-borne encephalitis virus. The flavivirus genome encodes a single protein that is responsible for the replication and transmission of the virus. The virus replicates in the cytoplasm of infected cells, leading to the production of new viral particles and the eventual spread of the infection.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct viral family. While the virus is tick-borne, the family is not accurate.
**Option B:** This option is incorrect because it is a viral family that includes viruses such as the HIV and the Hepatitis C virus, which are not tick-borne.
**Option C:** This option is incorrect because it is a viral family that includes viruses such as the Influenza virus and the Respiratory Syncytial virus, which are not tick-borne.
**Clinical Pearl / High-Yield Fact**
The Kyasanur Forest Disease virus is primarily transmitted through the bite of an infected tick, and the risk of transmission is highest in areas where the tick population is dense. In addition to ticks, the virus can also be transmitted through contact with infected animals, such as rodents and deer.
**Correct Answer: A. Flavivirus**