Sociodemographic factors associated with Kyasanur forest disease in India - a retrospective study

Objectives

Kyasanur forest disease (KFD) is a tick-borne disease in India affecting humans and two local non-human primate species. A critical knowledge gap in the scientific literature is the lack of information on how people's sociodemographic factors influence KFD occurrence.

Methods

We analyzed available data on KFD from three data sources: (a) 104 peer-reviewed articles using keyword searches on PubMed Central and Google Scholar, (b) 116 Program for Monitoring Emerging Diseases reports, and (c) an acute febrile illness surveillance data set on KFD from a report by the government of India. We performed statistical analyses to calculate the prevalence of KFD by state and differences in KFD cases by sex and age group.

Results

All three data sets used indicate that KFD cases and deaths have occurred predominantly in the 15-64 years age group (literature: 87% cases and 95% deaths, Program for Monitoring Emerging Diseases: 78% cases and 78% deaths, acute febrile illness: 96% cases [no breakdown for acute febrile illness death data]). Data reporting varies across states and is non-standardized.

Conclusions

The inconsistent reporting of sociodemographic data on KFD in India has created a gap in our understanding of its impact on different social groups. Collecting and reporting data on sociodemographic factors is critical to understanding the epidemiology of KFD and designing effective public health interventions.

Influence of environmental factors on tick diversity and abundance in different animal resting habitats in forest areas of the south Western Ghats

Most tick-borne disease causing pathogens originate in wildlife and are zoonotic in nature. A key to protecting human and animal health is to understand the biology and ecology of tick establishment. The tick distribution in wild animal habitats has been attributed to multiple environmental factors, and the studies on this topic are limited. Therefore, the objective of the study is to understand the influence of environmental factors on tick diversity and abundance in wild animal resting habitats. The study was carried out in 21 different animal resting habitats in the forest areas of Wayanad district, and they were divided into three groups based on the presence or absence of selected environmental parameters. A total of 10,849 ticks with 12 species belonging to five genera were collected. Regardless of the type of habitats, Haemaphysalis spinigera (59.52%) and Haemaphysalis turturis (33.20%) were the dominant species. Tick abundance showed greater variability between types of habitats ranging from 1.23 to 28.5. The greatest diversity and abundance were found in the group one. The group 3 had greater diversity and less abundance than the group 2. Both Simpson's diversity index and Shannon's diversity index were high for groups 2. Substantial variation in diversity and abundance of ticks occurred in different groups based on different environmental factors. The dominance of ticks of the genus Haemaphysalis a primary vector of Kyasanur Forest Disease highlights the need to carry out various control strategies to reduce the tick population.

Does the rise in cases of Kyasanur forest disease call for the implementation of One Health in India?

The viral hemorrhagic illness known as Kyasanur forest disease (KFD), also referred to as monkey fever, is transmitted by ticks. The etiological agent, which was formerly isolated from monkeys, is Kyasanur forest disease virus (KFDV), an RNA virus belonging to the family Flaviviridae. Since 1957, India has reported 400-500 cases annually, with a case fatality rate of 1-3%. Shiroma, Chikkamagalore, Uttara Kannada, Dakshina Kannada, and Udupi are the five regions in Karnataka, India where KFD is highly prevalent, with around 3263 notified cases reported between 2003 and 2012, of which 823 cases were laboratory confirmed. The symptoms of monkey fever can range from mild sickness to severe neurological sequelae. Currently, prophylaxis involves administration of formalin-inactivated tissue culture vaccine. Despite the continuing vaccination programs in endemic areas for KFD, new cases are being reported. The current availability and effectiveness of the vaccine are not enough to provide protective immunity and thus prevent new outbreaks. Our study examined the known literature, knowledge gaps, and host responses associated with KFD. There is a need for robust vector control, public awareness campaigns, mass vaccination programmes, a full understanding of the eco-epidemiological elements of the disease, and implementation of a One Health program. These could all support prevention and management protocols, and thus help to address the issue.

Sofosbuvir and its tri-phosphate metabolite inhibit the RNA-dependent RNA polymerase activity of non-structural protein 5 from the Kyasanur forest disease virus

Kyasanur forest disease is a neglected zoonotic disease caused by a single-stranded RNA-based flavivirus, the incidence of which was first recorded in 1957 in the Southern part of India. Kyasanur forest disease virus is transmitted to monkeys and humans through the infected tick bite of Haemophysalis spinigera. Kyasanur forest disease is a febrile illness, which in severe cases, results in neurological complications leading to mortality. The current treatment regimens are symptomatic and supportive, and no targeted therapies are available for this disease. In this study, we evaluated the ability of FDA-approved drugs sofosbuvir (and its active metabolite) and Dasabuvir to inhibit the RNA-dependent RNA polymerase activity of NS5 protein from the Kyasanur forest disease virus. NS5 protein containing the N-terminal methyl transferase domain and C-terminal RNA-dependent RNA polymerase domain was expressed in Escherichia coli, and RNA-dependent RNA polymerase activity was demonstrated with the purified protein. The RNA-dependent RNA polymerase assay conditions were optimized, followed by the determination of apparent K_m,ATP to validate the enzyme preparation. Half maximal-inhibitory concentrations against RNA-dependent RNA polymerase activity were determined for Sofosbuvir and its active metabolite. Dasabuvir did not show detectable inhibition with the tested conditions. This is the first demonstration of the inhibition of RNA-dependent RNA polymerase activity of NS5 protein from the Kyasanur forest disease virus with small molecule inhibitors. These initial findings can potentially facilitate the discovery and development of targeted therapies for treating Kyasanur forest disease.

Exploring potential inhibitors against Kyasanur forest disease by utilizing molecular dynamics simulations and ensemble docking

Kyasanur forest disease (KFD) is a tick-borne, neglected tropical disease, caused by KFD virus (KFDV) which belongs to Flavivirus (Flaviviridae family). This emerging viral disease is a major threat to humans. Currently, vaccination is the only controlling method against the KFDV, and its effectiveness is very low. An effective control strategy is required to combat this emerging tropical disease using the existing resources. In this regard, in silico drug repurposing method offers an effective strategy to find suitable antiviral drugs against KFDV proteins. Drug repurposing is an effective strategy to identify new use for approved or investigational drugs that are outside the scope of their initial usage and the repurposed drugs have lower risk and higher safety compared to de novo developed drugs, because their toxicity and safety issues are profoundly investigated during the preclinical trials in human/other models. In the present work, we evaluated the effectiveness of the FDA approved and natural compounds against KFDV proteins using in silico molecular docking and molecular simulations. At present, no experimentally solved 3D structures for the KFD viral proteins are available in Protein Data Bank and hence their homology model was developed and used for the analysis. The present analysis successfully developed the reliable homology model of NS3 of KFDV, in terms of geometry and energy contour. Further, in silico molecular docking and molecular dynamics simulations successfully presented four FDA approved drugs and one natural compound against the NS3 homology model of KFDV. Communicated by Ramaswamy H. Sarma.

Identification of bio-climatic determinants and potential risk areas for Kyasanur forest disease in Southern India using MaxEnt modelling approach

BACKGROUND

Kyasanur forest disease (KFD), known as monkey fever, was for the first time reported in 1957 from the Shivamogga district of Karnataka. But since 2011, it has been spreading to the neighbouring state of Kerala, Goa, Maharashtra, and Tamil Nadu. The disease is transmitted to humans, monkeys and by the infected bite of ticks Haemaphysalis spinigera. It is known that deforestation and ecological changes are the main reasons for KFD emergence, but the bio-climatic understanding and emerging pathways remain unknown.

METHODS

The present study aims to understand the bio-climatic determinants of distribution of tick vector of KFD in southern India using the Maximum Entropy (MaxEnt) model. The analysis was done using 34 locations of Haemaphysalis spinigera occurrence and nineteen bio-climatic variables from WorldClim. Climatic variables contribution was assessed using the Jackknife test and mean AUC 0.859, indicating the model performs with very high accuracy.

RESULTS

Most influential variables affecting the spatial distribution of Haemaphysalis spinigera were the average temperature of the warmest quarter (bio10, contributed 32.5%), average diurnal temperature range (bio2, contributed 21%), precipitation of wettest period (bio13, contributed 17.6%), and annual precipitation (bio12, contributed 11.1%). The highest probability of Haemaphysalis spinigera presence was found when the mean warmest quarter temperature ranged between 25.4 and 30 °C. The risk of availability of the tick increased noticeably when the mean diurnal temperature ranged between 8 and 10 °C. The tick also preferred habitat having an annual mean temperature (bio1) between 23 and 26.2 °C, mean temperature of the driest quarter (bio9) between 20 and 28 °C, and mean temperature of the wettest quarter (bio8) between 22.5 and 25 °C.

CONCLUSIONS

The results have established the relationship between bioclimatic variables and KFD tick distribution and mapped the potential areas for KFD in adjacent areas wherein surveillance for the disease is warranted for early preparedness before the occurrence of outbreaks etc. The modelling approach helps link bio-climatic variables with the present and predicted distribution of Haemaphysalis spinigera tick.

Low mammalian species richness is associated with Kyasanur Forest disease outbreak risk in deforested landscapes in the Western Ghats, India

Kyasanur forest disease virus (KFDV) is a rapidly expanding tick-borne zoonotic virus with natural foci in the forested region of the Western Ghats of South India. The Western Ghats is one of the world's most important biodiversity hotspots and, like many such areas of high biodiversity, is under significant pressure from anthropogenic landscape change. The current study sought to quantify mammalian species richness using ensemble models of the distributions of a sample of species extant in the Western Ghats and to explore its association with KFDV outbreaks, as well as the modifying effects of deforestation on this association. Species richness was quantified as a composite of individual species' distributions, as derived from ensembles of boosted regression tree, random forest, and generalised additive models. Species richness was further adjusted for the potential biotic constraints of sympatric species. Both species richness and forest loss demonstrated strong positive associations with KFDV outbreaks, however forest loss substantially modified the association between species richness and outbreaks. High species richness was associated with increased KFDV risk but only in areas of low forest loss. In contrast, lower species richness was associated with increased KFDV risk in areas of greater forest loss. This relationship persisted when species richness was adjusted for biotic constraints at the taluk-level. In addition, the taluk-level species abundances of three monkey species (Macaca radiata, Semnopithecus hypoleucus, and Semnopithecus priam) were also associated with outbreaks. These results suggest that increased monitoring of wildlife in areas of significant habitat fragmentation may add considerably to critical knowledge gaps in KFDV epidemiology and infection ecology and should be incorporated into novel One Health surveillance development for the region. In addition, the inclusion of some primate species as sentinels of KFDV circulation into general wildlife surveillance architecture may add further value.

Experiences of Indian Council of Medical Research with tick-borne zoonotic infections: Kyasanur Forest disease & Crimean-Congo haemorrhagic fever in India with One Health focus

Emergence and re-emergence of several pathogens have been witnessed by this century in the form of outbreaks, epidemics and pandemics. In India, the influencing factor that promotes dissemination of emerging and re-emerging viral infections is the biogeographical zones: a megadiverse country, characterized by varied geographical, climatic conditions and ever-changing socio-economical and geopolitical issues. These influence the movement of humans and animals and add layers of complexity for the identification and timely management of infectious diseases. This review focuses on two tick-borne infections: Crimean-Congo haemorrhagic fever (CCHF) and Kyasanur forest disease (KFD). In the last two decades, these viruses have emerged and caused outbreaks in different parts of India. KFD virus was initially identified in 1957 and was known to be endemic in Karnataka State while CCHF virus was first identified during 2010 in Gujarat State, India. These viruses have managed to emerge in new areas within the last decade. With changing epidemiology of these arboviruses, there is a probability of the emergence of these viruses from new areas in future. The investigations on these two diseases under the One Health focus involved early detection, quickly developing diagnostic tools, identifying stakeholders, capacity building by developing collaboration with major stakeholders to understand the epidemiology and geographical spread in domestic animal reservoirs and tick vectors in the affected areas, developing laboratory network, providing diagnostic reagents and biosafety and laboratory diagnosis training to the network laboratories to control these diseases.

Point of care real-time polymerase chain reaction-based diagnostic for Kyasanur forest disease

OBJECTIVES

Due to the remote forest area locations of sporadic cases and outbreaks of Kyasanur forest disease (KFD), rapid diagnosis poses a significant challenge. This study aimed to evaluate the diagnostic performance of Truenat KFD, a simple, rapid and user-friendly point-of-care test for detection of KFD and compare diagnostic accuracy with conventional real-time reverse transcription-polymerase chain reaction (RT-PCR) testing. Truenat KFD can be deployed in a field laboratory setting.

METHODS

The study involved 145 clinical specimens, including human serum, monkey necropsy tissues and tick pool, to validate Truenat KFD (Molbio Diagnostics Pvt.Ltd.) for KFD diagnosis.

RESULTS

We have optimized and validated the microchip-based Truenat KFD (Molbio Diagnostics Pvt.Ltd.) for KFD diagnosis. Point-of-care testing was highly sensitive and specific, with a detection limit of up to 10 copies of KFD viral RNA. Results were comparable with the gold-standard TaqMan and commercially available Altona RealStar AHFV / KFDV real-time RT-PCR assays. Screening results for human, monkey and tick specimens were 100% concordant across the assays.

CONCLUSION

Truenat KFD(Molbio Diagnostics Pvt.Ltd.) was found to be highly sensitive and specific with a significant limit of detection. This point-of-care test would be useful in rapid diagnosis of KFD in remote and/or field settings, quick patient management and control of virus spread.

Kinetics of viral RNA, immunoglobulin-M & G antibodies in Kyasanur forest disease

Background & objectives:

Kyasanur forest disease (KFD) is an infectious disease discovered in Karnataka State of India in 1957; since then, the State has been known to be enzootic for KFD. In the last few years, its presence was observed in the adjoining five States of the Western Ghats of India. The present study was conducted to understand the kinetics of viral RNA, immunoglobulin M (IgM) and IgG antibody in KFD-infected humans for developing a diagnostic algorithm for KFD.

Methods:

A prospective follow up study was performed among KFD patients in Sindhudurg district of Maharashtra State, India. A total of 1046 suspected patients were tested, and 72 KFD patients were enrolled and followed for 17 months (January 2016 to May 2017). Serum samples of KFD patients were screened for viral RNA, and IgM and IgG antibodies.

Results:

KFD viral positivity was observed from 1^st to 18^th post-onset day (POD). Positivity of anti-KFD virus (KFDV) IgM antibodies was detected from 4^th till 122^nd POD and anti-KFDV IgG antibodies detected from 5^th till 474^th POD. A prediction probability was determined from statistical analysis using the generalized additive model in R-software to support the laboratory findings regarding viral kinetics.

Interpretation & conclusions:

This study demonstrated the presence of KFD viral RNA till 18^th POD, IgM antibodies till 122^nd POD and IgG till the last sample collected. Based on our study an algorithm was recommended for accurate laboratory diagnosis of KFDV infection. A sample collected between 1 and 3 POD can be tested using KFDV real-time reverse transcriptase polymerase chain reaction (RT-PCR); between 4 and 24 POD, the combination of real-time RT-PCR and anti-KFDV IgM enzyme-linked immunosorbent assay (ELISA) tests can be used; between POD 25 and 132, anti-KFDV IgM and IgG ELISA are recommended.

Clinical & epidemiological significance of Kyasanur forest disease

Kyasanur forest disease (KFD) is a known viral haemorrhagic fever in India, for the last 60 years. However, in recent years, the change in epidemiological profile of the disease has suggested that it is now time to consider KFD as an emerging tropical disease in India. The preference should be to educate not only the villagers where it is being reported or detected but also to public health experts, veterinarians, forest officials and medical professionals to pay attention while seeing a patient overlapping with endemic diseases such as Japanese encephalitis, West Nile, dengue, chikungunya, malaria and tuberculosis. Although the existence of KFD is known for a long time, updated understanding of its clinical profile in humans is still limited. This article describes in detail the clinical presentation of KFD reported till date. It also highlights geographical distribution of the disease, risk factors for virus transmission, biochemical/haematological findings and control measures. There is an urgent need for research on KFD, particularly for understanding biphasic nature of illness, development of cost-effective diagnostic tools, utility of non-invasive samples for diagnosis and development of new vaccines.

Prevalence and spatial distribution of Ixodid tick populations in the forest fringes of Western Ghats reported with human cases of Kyasanur forest disease and monkey deaths in South India

Kyasanur forest disease (KFD) is a major tick-borne viral haemorrhagic fever caused by KFD virus (KFDV) (Flaviviridae). The disease was reported to be confined to five districts of Karnataka state India until 2011. During 2012-2016, emergence of KFD has been reported in newer areas of Karnataka and adjoining states. Therefore, survey of tick vectors was carried out in these new areas of Karnataka and adjoining states reported with monkey deaths and human cases of KFD. In all selected sites, ticks from the forest floor were collected by lint clothes using flagging method. Tick samples were tested for KFDV nucleic acid by real-time RT-PCR. A total of 4772 ticks, comprising eight species of genus Haemaphysalis and one species each of genus Amblyomma, Ixodes and Rhipicephalus was collected. Haemaphysalis spinigera, the principal vector of KFDV was the predominant tick species (59.5%) collected followed by H. turturis (8.6%). The abundance of H. spinigera ranged from 9.2 to 33.9 per man-hour in the six districts surveyed. Of 214 (4418 tick samples) pools screened by real-time RT-PCR, two pools of H. spinigera were positive for KFDV. High abundance of Haemaphysalis vectors in the six districts indicated that the districts are receptive for KFD outbreaks. KFDV was detected in the tick vectors in the new foci of the KFD. Data on tick distribution will be useful in creating KFD risk map for strengthening the ongoing preventive measures such as vaccination and supply of insect repellents to the high risk groups and intensive health education.

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.

Kyasanur forest disease virus breaking the endemic barrier: An investigation into ecological effects on disease emergence and future outlook

Kyasanur Forest disease (KFD) is found in a limited range of India, but is epidemiologically understudied. The seasonal patterns of KFD are well known; however, the significant concern is on the extent to which changes in epidemiology happen especially under the influence of ecological destructions and by the eventual effects of resulting climate change. Presently, a southward and northward spread of the Kyasanur Forest disease virus (KFDV) along the Western Ghats has been reported in the adjoining states of Kerala, Tamil Nadu, Goa and Maharashtra. In this review, we investigate the cascade of factors that might have facilitated the resurgence of KFDV among the endemic regions in higher frequency and its recent emergence in the area previously not reported. Utilizing published data, we additionally endeavour to exhibit a portion of the impediments of control systems and embody the powerful option strategies for developing KFDV control.

An outbreak of Kyasanur forest disease in the Wayanad and Malappuram districts of Kerala, India

Kyasanur forest disease (KFD) is a zoonotic viral haemorrhagic fever and has been endemic to Karnataka State, India. Outbreaks of KFD were reported in new areas of Wayanad and Malappuram districts of Kerala, India during 2014-2015. Investigation of the outbreaks was carried out in these districts during May 2015. The line-list data of KFD cases available with District Medical Office, Wayanad were analysed. Case investigation was carried out to determine the risk factors associated with the outbreak and possible site of contraction infections. Ticks from the forest floor were collected in areas associated with monkey deaths by flagging method to estimate species abundance. Of 102 confirmed cases of KFD reported in Wayanad, 91% were adults aged >15years. About 43% of the cases were from the areas of Poothady Primary Health Centre (PHC) followed by Chethalayam PHC (22%). Most of the affected individuals belong to Kattunayakan tribe, dependent on forest for their livelihood. Those tribes are engaged in trench digging and fire line works in summer months and hence are at a higher risk. In Malappuram, the Cholanaickan tribe, are under high risk of exposure to infected ticks as they live deep in the forest and trap monkeys for game meat. High abundance of Haemaphysalis spinigera and H. turturis, the established vectors of KFD virus was recorded in all affected areas. Incidence of KFD cases/monkey deaths and high abundance of Haemaphysalis vectors in the forest ranges of Wayanad and Malappuram districts indicate that the area has become receptive for KFD outbreaks. Preventive measures (vaccination of high risk groups) coupled with intensive health education should be carried out prior to transmission season.