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This is for health personnel for purpose of health education and capacity building
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Kyasanur Forest DiseaseDr Gautham MS LecturerDept 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
CONTROLPersonal 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
CONTROLVaccination 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