Kyasanur Forest Disease Prevalence in Western Ghats Proven and Confirmed by Recent Outbreak in Maharashtra, India, 2016.

INTRODUCTION: Kyasanur forest disease (KFD) outbreak was confirmed in Dodamarg Taluka, Sindhudurga district (Maharashtra) in India during the year 2016. The rise in suspected KFD cases was reported in January 2016, peaked during March, and then declined gradually from April 2016. The outbreak was thoroughly investigated considering different socio-clinical parameters. METHODS: Total, 488 suspected KFD cases were investigated using KFD specific real-time RT-PCR and anti-KFDV IgM enzyme-linked immunosorbent assay (ELISA). Sero-epidemiological survey was carried out in the affected area using anti-KFDV IgG ELISA. RESULTS: Among suspected KFD cases, high age-specific attack rate (105.1 per 1000 persons) was observed in adults (aged 40-59 years). Out of 488 suspected KFD cases, 130 were laboratory confirmed. Of these, 54 cases were KFDV real-time RT-PCR positive, 66 cases were anti-KFDV IgM ELISA positive and 10 cases were positive by both the assays. Case fatality ratio among laboratory-confirmed KFD cases were 2.3% (3/130). Majority of laboratory-confirmed KFD cases (93.1%) had visited Western Ghats forest in Dodamarg for activities like working in cashew nut farms (79.8%), cashew nut fruit collection (76.6%), collection of firewood (68.5%) and dry leaves/grass (40.3%), etc., before the start of symptoms. Common clinical features included fever (100%), headache (93.1%), weakness (84.6%), and myalgia (83.1%). Hemorrhagic manifestations were observed in nearly one-third of the laboratory-confirmed KFD cases (28.5%). A seroprevalence of (9.7%, 72/745) was recorded in KFD-affected area and two neighboring villages (9.1%, 15/165). Serosurvey conducted in Ker village showed clinical to subclinical ratio of 6:1 in KFD-affected areas. CONCLUSION: This study confirms the outbreak of KFD Sindhudurg district with 130 cases. Detection of anti-KFDV IgG antibodies among the healthy population in KFD-affected area during the KFD outbreak suggested the past exposure of KFD infection. This outbreak investigation has helped health authorities in adopting KFD vaccination strategy for the population at risk.

Clinical study of 100 cases of Kyasanur Forest disease with clinicopathological correlation.

100 cases of Kyasanur Forest Disease were studied clinically and autopsy or postmortem biopsies of various organs were done in 8 cases. 1. Our study showed that KFD passes through 4 stages each lasting for about a week. i.e. a prodromal stage with fever, hypotension hepatomegaly, a stage of complication characterized by haemorrhage, neurological manifestation or bronchopneumonia, a stage of recovery followed by a li stage of fever in some cases. 2. The exact of cause of haemorrhage could not be identified though Disseminated Intravascular Coagulation was suspected. 3. Hypotension in KFD could be of Myocardial origin. 4. Encephalopathy in KFD could be due to a metabolic cause probably of hepatic origin. 5. Lung signs could be due to intraalveolar haemorrhage and secondary infection.

The epizootics of Kyasanur Forest disease in wild monkeys during 1964 to 1973.

In the Kyasanur Forest disease area two species of wild monkeys, Presbytis entellus and Macaca radiata, succumb to the natural infection with Kyasanur Forest disease (KFD) virus (family Flaviviridae). Between October 1964 and September 1973, 1046 monkeys (860 P. entellus and 186 M. radiata) died. Of these, KFD virus was isolated from 118 P. entellus and 13 M. radiata. Maximum mortality of monkeys was reported during December through May coinciding with the season of activity of immature stages of Haemaphysalis ticks, incriminated vectors of KFD. The epizootic showed an initial spread of the disease to the areas contiguous with the original focus of infection. This was followed by the recognition of epizootics and epidemics in three new foci, removed from the original focus, by the end of 1973. It was also observed that, in certain localities in the original focus, KFD virus activity persisted over several years.