Kyasanur forest disease
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Kyasanur forest disease

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

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

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Kyasanur forest disease Kyasanur forest disease Presentation Transcript

  • Kyasanur Forest Disease Dr Gautham MS Lecturer Dept of Community Medicine M S Ramaiah Medical College
  • 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
  • History …….
    • Autopsy on monkeys
    • Place of reporting of First monkey death in march 1957
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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.
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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%
  • Treatment
    • Conservative
    • Antipyretics
    • Analgesics
    • Supportive therapy
  • 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
  • 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
  • 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
  • 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
  • Bio safety concerns
    • One of the highest risk category pathogens
    • Bio safety level 4
    • One of the potential bioterrorist weapon
    • THANK YOU