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Kyasanur forest disease


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This is for health personnel for purpose of health education and capacity building

Published in: Health & Medicine

Kyasanur forest disease

  1. 1. Kyasanur Forest Disease Dr Gautham MS Lecturer Dept of Community Medicine M S Ramaiah Medical College
  2. 2. History ….. <ul><li>Heavy mortality in two species of monkey </li></ul><ul><li>( Langur & Red faced bonnet ) in 1955 in forests of Shimoga led to the discovery of KFD </li></ul><ul><li>Mortality in monkeys was followed by acute febrile prostrating illness among villagers and few human deaths </li></ul>
  3. 3. History ……. <ul><li>Autopsy on monkeys </li></ul><ul><li>Place of reporting of First monkey death in march 1957 </li></ul>
  4. 4. Kyasanur forest disease <ul><li>Found in India </li></ul><ul><li>Limited originally to Shimoga district in Karnataka (800 sq km </li></ul><ul><li>Newer foci in 3 more districts namely U.kannada,D. Kannada and Chikmangaluru </li></ul><ul><li>( 6000 sq km ) </li></ul><ul><li>Serosurveys reveal KFD in Kutch & Saurashthra </li></ul>
  5. 5. Problem statement <ul><li>The outbreak during 1983-1984 is the largest with 2167 cases and 69 deaths. </li></ul><ul><li>In 1997 the cases came down to75 and deaths to 4. </li></ul><ul><li>The number of human deaths varied between 4-15% of the cases </li></ul><ul><li>Even today few hundreds of cases and some deaths are reported </li></ul>
  6. 6. Agent factors .. <ul><li>Kyasanur forest disease (KFD) is a febrile disease associated with hemorrhages caused by an arbovirus flavivirus. </li></ul><ul><li>KFD virus is a member of group B togaviruses </li></ul><ul><li>Belongs to Russian spring summer encephalitis (RSSE) group of viruses </li></ul>
  7. 7. HOST FACTORS <ul><li>Age :majority between 20 and 40 years. </li></ul><ul><li>Sex: males </li></ul><ul><li>Occupation: Cultivators who visit forest with cattle or cutting wood. </li></ul><ul><li>Epidemic correlates with peak human activity in forests i.e between January and June </li></ul>
  8. 8. Natural hosts & reservoirs <ul><li>Circulates in small mammals rats, squirrels, shrews and bats are the main reservoirs . </li></ul><ul><li>Neutralizing antibodies have also been found in cattle, buffaloes, goats and porcupines </li></ul><ul><li>Maintenance hosts – maintain the infection in nature </li></ul>
  9. 9. Natural hosts & reservoirs <ul><li>Monkeys are the amplifying hosts for the virus. </li></ul><ul><li>Amplifying hosts --- multiplication of the virus takes place at very high levels such that the intensity of infection is very high. </li></ul>
  10. 10. Natural cycle <ul><li>In enzootic states the infection is maintained in small mammals and also in ticks </li></ul><ul><li>When monkeys come in contact with infected ticks , they get infected , amplify and disseminate the infection in “hot spots ”of infection </li></ul><ul><li>Humans in these hot spots are infected by bite of infected anthrophilic ticks like H. spinigera </li></ul>
  11. 11. VECTORS <ul><li>Female tick laying eggs </li></ul><ul><li>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 </li></ul><ul><li>Ticks act as both as vectors and reservoirs of infection in KFD </li></ul>
  12. 12. Vector bionomics and seasonal transmission of KFD <ul><li>Adult Ticks become active after few monsoon rains in June </li></ul><ul><li>Adult population reaches peak during July & August and gradually declines in September </li></ul><ul><li>Larval activity builds in post monsoon Oct-Dec </li></ul><ul><li>Nymphal activity high from January to May </li></ul>
  13. 13. Vector bionomics and seasonal transmission of KFD <ul><li>Epidemics coincide with nymphal activity </li></ul><ul><li>Nymph most important stage for human transmission of infection as viraemia is significant in nymphs </li></ul><ul><li>Adults ticks feed on cattle and viraemia is not significant </li></ul>
  14. 14. Environmental factors <ul><li>Tropical evergreen, deciduous forests </li></ul><ul><li>Clearing of forests for cultivation and other developmental activities leads to change in tick flaura and fauna and is an important determinant for outbreaks </li></ul>
  15. 15. MODE OF TRANSMISSION <ul><li>By the bite of infective ticks.(nymphal stage ) </li></ul><ul><li>Human is dead end in the natural cycle </li></ul><ul><li>There is no evidence of man to man transmission </li></ul><ul><li>Transtadial transmission is common in ticks but transovarial transmission is absent except in Ixodides species </li></ul>
  16. 16. CLINICAL FEATURES <ul><li>Acute phase with sudden onset of fever, headache ,severe myalgia with prostation lasting for 2 weeks. </li></ul><ul><li>GI disturbances and hemorrhagic manifestations in severe cases </li></ul><ul><li>Second phase characterized by mild meningoencephalitis after an afebrile period of 7-21 days. </li></ul><ul><li>Case fatality varies between 4-16% </li></ul>
  17. 17. Treatment <ul><li>Conservative </li></ul><ul><li>Antipyretics </li></ul><ul><li>Analgesics </li></ul><ul><li>Supportive therapy </li></ul>
  18. 18. Diagnosis <ul><li>Diagnosis by suspicion by clinical signs and symptoms </li></ul><ul><li>H/O occupation/travel in forests </li></ul><ul><li>Detecting the presence of virus in blood. </li></ul><ul><li>Serological evidence by haemagglutination and immunofloresence </li></ul>
  19. 19. CONTROL <ul><li>Timely control decreases morbidity and mortality in humans </li></ul><ul><li>CONTROL OF TICKS </li></ul><ul><li>By aircraft mounted equipment to dispense lindane , cabaryl fenthion at 2.24 kg / hectare at forest floor </li></ul><ul><li>Spraying carried out within 50m around hot spots </li></ul><ul><li>Restriction of cattle movement brings reduction in vector population </li></ul>
  20. 20. CONTROL <ul><li>Personal protection </li></ul><ul><li>Adequate clothing </li></ul><ul><li>Insect repellants such as DMP, DEET provide 90-100% protection against tick bites </li></ul><ul><li>Examine themselves for ticks and promptly remove them </li></ul><ul><li>Health education </li></ul>
  21. 21. CONTROL <ul><li>Vaccination </li></ul><ul><li>Inactivated chick embryo tissue culture vaccine developed by NIV, Pune </li></ul><ul><li>Neutralizing antibodies in 70% of vaccinated persons </li></ul><ul><li>Vaccinating at risk population i.e villagers living near forests , forest workers , occupational personnel concerned with forests </li></ul>
  22. 22. Bio safety concerns <ul><li>One of the highest risk category pathogens </li></ul><ul><li>Bio safety level 4 </li></ul><ul><li>One of the potential bioterrorist weapon </li></ul>
  23. 23. <ul><li>THANK YOU </li></ul>