Outbreak of Kyasanur Forest Disease in Shivamogga , Karnataka State , India , during 2015

KFD was initially restricted to 5 districts, Shivamogga, Chikkamagalore, Uttara kannada, Dakshina kannada and Udupi, but Chamarajanagara, District of Karnataka state also reported for KFD during 2012-13 [4]. Usually, KFD cases were reported from December May and there will be around 100-500 infections on an average every year [2]. Hence, the present work was conducted to study the epidemiological distribution of KFD outbreak during the year 2015 in Karnataka (State) and compare it with the KFD outbreak, 2014.


Introduction
Kyasanur Forest disease (KFD) is a tick-borne viral disease caused by Kyasanur Forest disease virus (KFDV), a member of the virus family Flaviviridae.Kyasanur Forest Disease was first discovered in 1956 in Kyasanur village of Soraba Taluk, Shivamogga District, Karnataka state, India [1].The KFDV spreads to monkeys and human beings through the bite of infected ticks.It mainly infects two types of monkeys, one is black faced langurs (Semnopethicus entellus) and red faced bonnet monkeys (Macaca radiate) and various tick species (Genus Hemaphysalis).KFDV infected ticks spread the virus after feeding onto healthy monkeys.Uninfected ticks get the virus by feeding infected monkeys.KFDV infection causes severe febrile illness in monkeys.After the death of infected monkeys, ticks drop off from the body of the dead monkeys and create the danger zone or hot spots of infectious ticks which spread the virus further by infecting healthy animals.KFDV circulates in the forest through different hosts like, rodents, shrews, birds, and ticks [2].KFDV infects human beings through the bite of infected ticks when the people enter the hot spot area of KFD.Infected individuals manifest symptoms of KFD like, high fever, headache, myalgia, bleeding from nasal cavity, throat, gingivae and gastrointestinal tract [3].

Outbreak of Kyasanur Forest Disease in Shivamogga, Karnataka State, India, during 2015
Copyright: © 2017 Thippeswamy and Kiran Human serum samples, monkey brain, liver, heart, lungs, kidney and tick pools were sonicated in 600ml of minimum essential media (GIBCO/ BRL, Life technologies, Grand Island, NY, USA) and 400ml of media was added to the homogenate, Tripure isolation reagent (Roche Diagnostics, Indianapolis, in USA) was used to perform RNA extraction as described by Mourya et al , [5].Samples were tested for KFDV by nested reverse transcription PCR (RT-PCR) and real time RT-PCR as described by Mourya et al, [5].Human serum samples were also tested for the presence of IgM antibody by Elisa method.

Results and discussion
Highest number of cases reported between January to April because of high temperature before the commencement of rainfall.In 2015, maximum number of KFD cases was found in January when compared to remaining months (Table 1).41 out of 124 human samples were positive for KFDV and none of the 42 Monkey visceral samples and 158 tick pools was positive for KFDV (Table 1).In 2015, from January to July a total of 124 cases were suspected for KFD in 71 villages in Shivamogga district; laboratory testing confirmed only 41 were infected with KFDV from 21 villages.Nearly 81% (more than 100 out of 124) of suspected cases observed in 2015 and 77% (307 out of 400) suspected cases in 2014 were reported only from Thirthahalli (Virus diagnostic laboratory, Shimoga) Taluk, Shivamogga district [6], whereas in other districts like Chikkamagaluru, Uttarakannada, Dakshinakannada and Udupi, number of cases were very less.With the available data we can say that Thirthahalli Taluk, Shivamogga district is the hot spot for KFD (Figure1).In 2015, number of reported cases were 41 reduced by 75% when compared to 166 in 2014 (Table 1).This data shows, spreading of the disease is continuous but number of KFD incidences were randomly distributed in the infected

Outbreak of Kyasanur Forest Disease in Shivamogga, Karnataka State, India, during 2015
Copyright: © 2017 Thippeswamy and Kiran area.The number of incidences of KFD differs with different districts, where Shivamogga district has more number of KFD cases compared to Uttarakannada and Chikkamagalur (Figure 2).Year wise, the number of incidences of KFD fluctuating very much, it shows the uncertainty of KFD cases in every year.In the year 2012, number of cases were 97, cases were reduced to 17 in 2013 whereas in 2014 positive cases increased to 166 and again reduced to 41 in 2015 (Table 2).We have also compared the data of KFD cases year wise from 2011-12 to 2014-15 as well as month wise (Figure 3).The graph clearly indicated the number of incidences of KFD were more from January-May, where increased temperature correlated with increased incidences of KFD.From the month of June no cases of KFD were found because of onset of monsoon during which ticks enter into non feeding phase of metamorphosis.It is very difficult to predict the place and time of KFD outbreak since 1956.The KFDV keeps on spreading towards north-west and south-west from the place of its discovery.To control mortality and morbidity of KFD following things needs to be done; development of quick diagnostic tool for the early and accurate diagnosis of the disease, discovery of drug to treat the patients of KFD and improvement of the efficacy of the current vaccine.

Figure 1 :
Figure 1: Map of India showing the rate of incidences reported in 3 different regions of Karnataka.

Figure 2 :
Figure 2: District wise incidence of Kyasanur forest disease in Karnataka state for the year 2015.

Table 1 :
Data showed the incidences of Kyasanur Forest disease with month wise in Karnataka state for the year 2015.

Table 2 :
Data showed the incidences of KFD cases, Monkeys death and tick pools from 2012-2015, Karnataka.