Kyasanur Forest Disease (KFD) is an tick-borne viral hemorrhagic fever endemic to the Kyasanur Forest in Karnataka, India. It is caused by the Kyasanur Forest disease virus (KFDV), a member of the Flaviviridae family. The disease is transmitted to humans through the bite of infected ticks or from contact with infected animal blood or tissue during slaughtering or preparing meat.

The initial symptoms of KFD include sudden onset of fever, headache, muscle pain, and severe weakness. After a few days, gastrointestinal symptoms such as nausea, vomiting, and diarrhea may occur. In some cases, the disease can progress to cause bleeding from the mucous membranes, bloody stools, and internal hemorrhages, which can be life-threatening.

There is no specific treatment for KFD, and management is focused on supportive care, such as fluid replacement and pain relief. Prevention measures include avoiding tick-infested areas, using protective clothing and insect repellents, and vaccination of high-risk populations.

Tick-borne encephalitis (TBE) viruses are a group of related viruses that are primarily transmitted to humans through the bite of infected ticks. The main strains of TBE viruses include:

1. European tick-borne encephalitis virus (TBEV-Eu): This strain is found mainly in Europe and causes the majority of human cases of TBE. It is transmitted by the tick species Ixodes ricinus.
2. Siberian tick-borne encephalitis virus (TBEV-Sib): This strain is prevalent in Russia, Mongolia, and China, and is transmitted by the tick species Ixodes persulcatus.
3. Far Eastern tick-borne encephalitis virus (TBEV-FE): Also known as Russian spring-summer encephalitis (RSSE) virus, this strain is found in Russia, China, and Japan, and is transmitted by the tick species Ixodes persulcatus.
4. Louping ill virus (LIV): This strain is primarily found in the United Kingdom, Ireland, Portugal, and Spain, and is transmitted by the tick species Ixodes ricinus. It mainly affects sheep but can also infect humans.
5. Turkish sheep encephalitis virus (TSEV): This strain is found in Turkey and Greece and is primarily associated with ovine encephalitis, although it can occasionally cause human disease.
6. Negishi virus (NGS): This strain has been identified in Japan and Russia, but its role in human disease remains unclear.

TBE viruses are members of the Flaviviridae family and are closely related to other mosquito-borne flaviviruses such as West Nile virus, dengue virus, and Zika virus. The incubation period for TBE is usually 7-14 days after a tick bite, but it can range from 2 to 28 days. Symptoms of TBE include fever, headache, muscle pain, fatigue, and vomiting, followed by neurological symptoms such as meningitis (inflammation of the membranes surrounding the brain and spinal cord) or encephalitis (inflammation of the brain). Severe cases can lead to long-term complications or even death. No specific antiviral treatment is available for TBE, and management typically involves supportive care. Prevention measures include avoiding tick-infested areas, using insect repellents, wearing protective clothing, and promptly removing attached ticks. Vaccination is also recommended for individuals at high risk of exposure to TBE viruses.