Kyasanur Forest Disease (KFD) is a viral hemorrhagic fever found in parts of India that is transmitted to humans via tick bites. The virus was first discovered in 1955 after monkeys in a forest died and villagers nearby fell ill. It is caused by a flavivirus and circulates in small forest mammals and ticks, with monkeys amplifying the virus. Humans are infected when bitten by infected ticks, most commonly the Haemaphysalis spinigera tick. KFD presents with acute fever, headache, and hemorrhagic symptoms and has a 4-16% fatality rate. Prevention focuses on controlling tick populations, limiting human exposure to forests, and vaccinating at-risk groups.

1. Kyasanur Forest Disease Dr Gautham MS Lecturer Dept of Community Medicine M S Ramaiah Medical College

2. History ….. Heavy mortality in two species of monkey ( Langur & Red faced bonnet ) in 1955 in forests of Shimoga led to the discovery of KFD Mortality in monkeys was followed by acute febrile prostrating illness among villagers and few human deaths

3. History ……. Autopsy on monkeys Place of reporting of First monkey death in march 1957

4. Kyasanur forest disease Found in India Limited originally to Shimoga district in Karnataka (800 sq km Newer foci in 3 more districts namely U.kannada,D. Kannada and Chikmangaluru ( 6000 sq km ) Serosurveys reveal KFD in Kutch & Saurashthra

5. Problem statement The outbreak during 1983-1984 is the largest with 2167 cases and 69 deaths. In 1997 the cases came down to75 and deaths to 4. The number of human deaths varied between 4-15% of the cases Even today few hundreds of cases and some deaths are reported

6. Agent factors .. Kyasanur forest disease (KFD) is a febrile disease associated with hemorrhages caused by an arbovirus flavivirus. KFD virus is a member of group B togaviruses Belongs to Russian spring summer encephalitis (RSSE) group of viruses

7. HOST FACTORS Age :majority between 20 and 40 years. Sex: males Occupation: Cultivators who visit forest with cattle or cutting wood. Epidemic correlates with peak human activity in forests i.e between January and June

8. Natural hosts & reservoirs Circulates in small mammals rats, squirrels, shrews and bats are the main reservoirs . Neutralizing antibodies have also been found in cattle, buffaloes, goats and porcupines Maintenance hosts – maintain the infection in nature

9. Natural hosts & reservoirs Monkeys are the amplifying hosts for the virus. Amplifying hosts --- multiplication of the virus takes place at very high levels such that the intensity of infection is very high.

10. Natural cycle In enzootic states the infection is maintained in small mammals and also in ticks When monkeys come in contact with infected ticks , they get infected , amplify and disseminate the infection in “hot spots ”of infection Humans in these hot spots are infected by bite of infected anthrophilic ticks like H. spinigera

11. VECTORS Female tick laying eggs Virus has been isolated from 16 species of ticks but Hard tick species of the genus Haemophysalis particularly H.spinigera and H.turtura are the main vectors Ticks act as both as vectors and reservoirs of infection in KFD

12. Vector bionomics and seasonal transmission of KFD Adult Ticks become active after few monsoon rains in June Adult population reaches peak during July & August and gradually declines in September Larval activity builds in post monsoon Oct-Dec Nymphal activity high from January to May

13. Vector bionomics and seasonal transmission of KFD Epidemics coincide with nymphal activity Nymph most important stage for human transmission of infection as viraemia is significant in nymphs Adults ticks feed on cattle and viraemia is not significant

14. Environmental factors Tropical evergreen, deciduous forests Clearing of forests for cultivation and other developmental activities leads to change in tick flaura and fauna and is an important determinant for outbreaks

15. MODE OF TRANSMISSION By the bite of infective ticks.(nymphal stage ) Human is dead end in the natural cycle There is no evidence of man to man transmission Transtadial transmission is common in ticks but transovarial transmission is absent except in Ixodides species

16. CLINICAL FEATURES Acute phase with sudden onset of fever, headache ,severe myalgia with prostation lasting for 2 weeks. GI disturbances and hemorrhagic manifestations in severe cases Second phase characterized by mild meningoencephalitis after an afebrile period of 7-21 days. Case fatality varies between 4-16%

17. Treatment Conservative Antipyretics Analgesics Supportive therapy

18. Diagnosis Diagnosis by suspicion by clinical signs and symptoms H/O occupation/travel in forests Detecting the presence of virus in blood. Serological evidence by haemagglutination and immunofloresence

19. CONTROL Timely control decreases morbidity and mortality in humans CONTROL OF TICKS By aircraft mounted equipment to dispense lindane , cabaryl fenthion at 2.24 kg / hectare at forest floor Spraying carried out within 50m around hot spots Restriction of cattle movement brings reduction in vector population

20. CONTROL Personal protection Adequate clothing Insect repellants such as DMP, DEET provide 90-100% protection against tick bites Examine themselves for ticks and promptly remove them Health education

21. CONTROL Vaccination Inactivated chick embryo tissue culture vaccine developed by NIV, Pune Neutralizing antibodies in 70% of vaccinated persons Vaccinating at risk population i.e villagers living near forests , forest workers , occupational personnel concerned with forests

22. Bio safety concerns One of the highest risk category pathogens Bio safety level 4 One of the potential bioterrorist weapon

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