On the transmission pattern of Kyasanur Forest disease (KFD) in India

Characterization of host receptor interaction with envelop protein of Kyasanur forest disease virus and predicting suitable epitopes for vaccine candidate

Kyasanur forest disease (KFD) is a zoonotic disease that is endemic to southern India and caused by KFD virus (KFDV) belonging to the family Flaviviridae. Humans are the dead-end host of the KFDV life cycle. The absence of effective treatment strategies against KFD can be attributed to a lack of studies on the mechanistic part of the spread of the disease. Hypothesizing molecular etiological similarity of KFDV to other well characterized flaviviruses, such as dengue virus (DENV), we focused on predicting the target receptor protein(s) in host and provided molecular basis of receptor-mediated recognition of the human host by KFDV envelop protein (EKFDV), drawing from the extant knowledge on the dengue counterpart, EDENV. Indeed, in silico approach helped to identify that the EKFDV structure closely resembles the EDENV structure and indicated DC-SIGN and/or Mannose receptors to be the plausible target host receptors. Immune-informatics approach aided in predicting 10 epitopes from E, NS1, NS2A, and NS2B proteins of the KFDV-P9605 genotype for vaccine design against KFDV. Further, molecular dynamics simulation (MDS) analyses of their complexes with human leukocyte antigens (HLAs) identified the epitopes DISLTCRVT and YAMEIRPVH as two high ranking candidates for vaccine design.Communicated by Ramaswamy H. Sarma.

Clinical, epidemiological, and molecular investigation of Kyasanur forest disease from Karnataka state, India during 2018-2019

BACKGROUND

In this study, we carried out an investigation of Kyasanur Forest Disease (KFD) suspected human cases reported in Karnataka state, India from December 2018 to June 2019.

METHODS

The clinical samples of KFD suspected cases (n = 1955) from 14 districts of Karnataka were tested for KFD using real-time RT-PCR and IgM ELISA. Further, the KFD-negative samples were tested for IgM antibodies against dengue and chikungunya viruses. Monkey samples (n = 276) and tick pools (n = 11582) were also screened using real-time RT-PCR. KFD-positive samples were further analysed using next-generation sequencing along with clinico-epidemiological analysis.

RESULTS

Of all, 173 (8.8%) cases tested positive for KFD either by real-time RT-PCR (n = 124), IgM ELISA (n = 53) or both tests (n = 4) from seven districts. Among KFD-negative cases, IgM antibody positivity was observed for dengue (2.6%), chikungunya (5.8%), dengue and chikungunya coinfection (3.7%). KFD cases peaked in January 2019 with fever, conjunctivitis, and myalgia as the predominant symptoms and a mortality of 4.6%. Among confirmed cases, 41% received a single dose and 20% received two doses of the KFD vaccine. Of the seven districts with KFDV positivity, Shivamogga and Hassan districts reported KFD viral RNA positivity in humans, monkeys, and ticks. Sequencing analysis of 2019 cases demonstrated a difference of less than 1.5% amino acid compared to prototype KFDV.

CONCLUSION

Although the KFD has been endemic in many districts of Karnataka state, our study confirms the presence of KFDV for the first time in two new districts, i.e. Hassan and Mysore. A comparative analysis of KFDV infection among the KFD-vaccinated and non-vaccinated populations demonstrated an insignificant difference.

Knowledge, Attitudes, and Practices Regarding Ticks, Tick-Borne Diseases, and Ethnomedicine Among an at-Risk Population in Kerala

Tick and tick-borne diseases (TBDs) are increasing annually, and the study of ticks has gained importance after the outbreak of Kyasanur Forest disease (KFD) in the South Western Ghats of India. Wayanad district of Kerala, with the highest tribal population in South India, is a KFD endemic state, owing to the lack of knowledge, attitude, and practice studies on TBDs and ethnomedicines against ticks. This study was carried out to assess their baseline knowledge, attitude, and ethnomedicinal practice against ticks. A structured questionnaire was used to conduct a survey of 499 tribal members living in forest fringe areas. Logistic regression analysis was performed to identify the factors that influence the knowledge, attitude, and practice of tribes on TBDs. More than 70% of the population visit the forests on a regular basis, with 65.7% of the population regularly exposed to tick bites; however, only 47.7% were aware of TBDs. About 47.4% of the respondents took precautions like therapeutics and natural remedies to avoid tick bites. Ten species of medicinal plant belonging to eight different families have been identified from the survey. The tribal population use these plants to repel ticks as well as treat tick bites. From the study, we concluded that the limited in-depth knowledge displayed by the tribes can be strengthened by conducting community programs such as awareness classes on TBD and its control measures. The ethnobotanicals identified can be used to formulate novel tick repellents in the future.

Primates and pandemics: A biocultural approach to understanding disease transmission in human and nonhuman primates

Investigations into zoonotic disease outbreaks have been largely epidemiological and microbiological, with the primary focus being one of disease control and management. Increasingly though, the human-animal interface has proven to be an important driver for the acquisition and transmission of pathogens in humans, and this requires syncretic bio-socio-cultural enquiries into the origins of disease emergence, for more efficacious interventions. A biocultural lens is imperative for the examination of primate-related zoonoses, for the human-primate interface is broad and multitudinous, involving both physical and indirect interactions that occur due to shared spaces and ecologies. I use the case example of a viral zoonotic epidemic that is currently endemic to India, the Kysanaur Forest Disease, to show how biocultural anthropology provides a broad and integrative perspective into infectious disease ecology and presents new insights into the determinants of disease outbreaks. Drawing on insights from epidemiology, political ecology, primate behavioral ecology and ethnoprimatology, this paper demonstrates how human-primate interactions and shared ecologies impact infectious disease spread between human and nonhuman primate groups.

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.

Transcriptome Profiling of Rhipicephalus annulatus Reveals Differential Gene Expression of Metabolic Detoxifying Enzymes in Response to Acaricide Treatment

Ticks are hematophagous ectoparasites of economic consequence by virtue of being carriers of infectious diseases that affect livestock and other sectors of the agricultural industry. A widely prevalent tick species, Rhipicephalus (Boophilus) annulatus, has been recognized as a prime vector of tick-borne diseases in South Indian regions. Over time, the use of chemical acaricides for tick control has promoted the evolution of resistance to these widely used compounds through metabolic detoxification. Identifying the genes related to this detoxification is extremely important, as it could help detect valid insecticide targets and develop novel strategies for effective insect control. We performed an RNA-sequencing analysis of acaricide-treated and untreated R. (B.) annulatus and mapped the detoxification genes expressed due to acaricide exposure. Our results provided high-quality RNA-sequenced data of untreated and amitraz-treated R. (B.) annulatus, and then the data were assembled into contigs and clustered into 50,591 and 71,711 uni-gene sequences, respectively. The expression levels of the detoxification genes across different developmental stages of R. (B.) annulatu identified 16,635 transcripts as upregulated and 15,539 transcripts as downregulated. The annotations of the differentially expressed genes (DEGs) revealed the significant expression of 70 detoxification genes in response to the amitraz treatment. The qRT-PCR revealed significant differences in the gene expression levels across different life stages of R. (B.) annulatus.

Using mechanistic models to highlight research priorities for tick-borne zoonotic diseases: Improving our understanding of the ecology and maintenance of Kyasanur Forest Disease in India

The risk of spillover of zoonotic diseases to humans is changing in response to multiple environmental and societal drivers, particularly in tropical regions where the burden of neglected zoonotic diseases is highest and land use change and forest conversion is occurring most rapidly. Neglected zoonotic diseases can have significant impacts on poor and marginalised populations in low-resource settings but ultimately receive less attention and funding for research and interventions. As such, effective control measures and interventions are often hindered by a limited ecological evidence base, which results in a limited understanding of epidemiologically relevant hosts or vectors and the processes that contribute to the maintenance of pathogens and spillover to humans. Here, we develop a generalisable next generation matrix modelling framework to better understand the transmission processes and hosts that have the greatest contribution to the maintenance of tick-borne diseases with the aim of improving the ecological evidence base and framing future research priorities for tick-borne diseases. Using this model we explore the relative contribution of different host groups and transmission routes to the maintenance of a neglected zoonotic tick-borne disease, Kyasanur Forest Disease Virus (KFD), in multiple habitat types. The results highlight the potential importance of transovarial transmission and small mammals and birds in maintaining this disease. This contradicts previous hypotheses that primates play an important role influencing the distribution of infected ticks. There is also a suggestion that risk could vary across different habitat types but currently more research is needed to evaluate this relationship. In light of these results, we outline the key knowledge gaps for this system and future research priorities that could inform effective interventions and control measures.

The role of social vulnerability in improving interventions for neglected zoonotic diseases: The example of Kyasanur Forest Disease in India

Forest-based communities manage many risks to health and socio-economic welfare including the increasing threat of emerging zoonoses that are expected to disproportionately affect poor and marginalised groups, and further impair their precarious livelihoods, particularly in Low-and-Middle Income (LMIC) settings. Yet, there is a relative dearth of empirical research on the vulnerability and adaptation pathways of poor and marginalised groups facing emerging zoonoses. Drawing on a survey of 229 households and a series of key-informant interviews in the Western Ghats, we examine the factors affecting vulnerability of smallholder and tribal households to Kyasanur Forest Disease (KFD), an often-fatal tick-borne viral haemorrhagic fever endemic in south India. Specifically, we investigate how different socio-demographic and institutional factors interact to shape KFD vulnerability and the strategies employed by households to adapt to disease consequences. Although surveyed households generally perceived KFD as an important health issue in the study region, there was variability in concern about contracting the disease. Overall results showed that poor access to land (AOR = 0.373, 95% CI: 0.152-0.916), being at or below the poverty line (AOR = 0.253, 95% CI: 0.094-0.685) and being headed by an older person (AOR = 1.038, 95% CI: 1.006-1.071) were all significant determinants of perceived KFD vulnerability. Furthermore, KFD vulnerability is also modulated by important extra-household factors including proximity to private hospitals (AOR = 3.281, 95% CI: 1.220-8.820), main roads (AOR = 2.144, 95% CI: 1.215-3.783) and study location (AOR = 0.226, 95% CI: 0.690-0.743). Our findings highlight how homogenous characterisation of smallholder and tribal communities and the 'techno-oriented' approach of existing interventions may further marginalise the most vulnerable and exacerbate existing inequalities. These findings are important for designing context-specific and appropriate health interventions (including the prioritisation of awareness raising, knowledge networks, livelihood diversification) that enhances the resilience of at-risk social groups within the KFD context. More broadly, our findings highlight how a focus on social vulnerability can help national and international health planners improve health interventions and prioritise among diseases with respect to neglected endemic zoonoses.

Dry- down probe free qPCR for detection of KFD in resource limited settings

Kyasanur Forest Disease is a tick-borne flavivirus is endemic in the Southern India. The recent expansion and resurgence of sporadic outbreaks in southern parts of country is the most important concern. Although only formalin inactivated vaccine is available for treatment with limited efficacy the early detection and timely identification is a only way to prevent spread of cases. If the disease can be identified prior to infection in humans like in forest areas from ticks and vectors the disease spread supposed to be managed quickly. Here we have standardized a single tube ready to use dry-down probe free real time RT-PCR targeted against virus envelope gene for detection of KFDV infection. The assay was standardized in liquid format first, later it was converted into dry-down format with addition of stabilizers with a similar sensitivity and specificity (10RNA Copies/rxn). The sensitivity was comparable to the most widely used and accepted diagnostic platform i.e. TaqMan qRT-PCR. However as the reported assay here omit the need of probes makes it cost effective and dry-down reagents makes more stability to the developed assay in this study if compare to TaqMan qPCR. The assay was evaluated with KFD positive samples and healthy sample panel which revealed high concordance with TaqMan qRT-PCR. Stability was unaffected by temperature fluctuations during transportation even in cold chain free conditions, thus reduce the maintenance of strict cold storage. These findings demonstrated that the reported assay is convenient with 100% sensitivity and specificity to TaqMan qPCR. Thus this assay has the potential usefulness for diagnosis KFDV for routine surveillance in resource limited laboratory settings omitting the use costly and heat sensitive TaqMan qRT-PCR reagents without compromising the sensitivity and specificity of the diagnosis assay.

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.

Kyasanur forest disease: a state-of-the-art review

Kyasanur forest disease (KFD) virus is a flavivirus that can be transmitted to humans from monkeys or other mammals through hard ticks (Haemaphysalis spinigera). The disease is endemic to 16 districts in 5 states of Southern India and is reported in the dry season, most commonly in humans travelling to the forests in these areas. The aim of this systematic review is to raise awareness of the clinical and laboratory manifestation of KFD among physicians and travel medicine practitioners. A total of 153 articles were screened of which 16 articles that met the inclusion and exclusion criteria were included for qualitative analysis. KFD is an acute haemorrhagic fever with a biphasic component in some individuals. The second phase is usually marked by neurological symptoms. Leucopoenia, thrombocytopenia and elevated transaminases are the hallmarks of the first phase of KFD. The diagnostic modality of choice in the first few days of illness is polymerase chain reaction assay, whereas serology is used in the late phase. In the absence of a specific antiviral treatment, the clinical management of patients is limited to supportive care. Avoidance of exposure and vaccination is recommended to prevent this infection.

Co-production of knowledge as part of a OneHealth approach to better control zoonotic diseases

There is increased global and national attention on the need for effective strategies to control zoonotic diseases. Quick, effective action is, however, hampered by poor evidence-bases and limited coordination between stakeholders from relevant sectors such as public and animal health, wildlife and forestry sectors at different scales, who may not usually work together. The OneHealth approach recognises the value of cross-sectoral evaluation of human, animal and environmental health questions in an integrated, holistic and transdisciplinary manner to reduce disease impacts and/or mitigate risks. Co-production of knowledge is also widely advocated to improve the quality and acceptability of decision-making across sectors and may be particularly important when it comes to zoonoses. This paper brings together OneHealth and knowledge co-production and reflects on lessons learned for future OneHealth co-production processes by describing a process implemented to understand spill-over and identify disease control and mitigation strategies for a zoonotic disease in Southern India (Kyasanur Forest Disease). The co-production process aimed to develop a joint decision-support tool with stakeholders, and we complemented our approach with a simple retrospective theory of change on researcher expectations of the system-level outcomes of the co-production process. Our results highlight that while co-production in OneHealth is a difficult and resource intensive process, requiring regular iterative adjustments and flexibility, the beneficial outcomes justify its adoption. A key future aim should be to improve and evaluate the degree of inter-sectoral collaboration required to achieve the aims of OneHealth. We conclude by providing guidelines based on our experience to help funders and decision-makers support future co-production processes.

Species distribution and ecological suitability analysis for potential tick vectors of Kyasanur forest disease in the Western Ghats of Kerala

Kyasanur forest disease (KFD) is a tick-borne zoonotic viral disease with an estimated case fatality rate of 3% to 5% in humans. The KFD virus is transmitted to both humans and animals by infected ticks, primarily the Haemaphysalis species. Our study was undertaken following reports of five confirmed cases and three deaths due to KFD in Malappuram district of Kerala in 2014 to determine the diversity of Ixodidae ticks on vegetation and their possible infection with the KFD virus. Overall, 3502 hard ticks belonging to three genera and eight species were collected from two forest divisions. Haemaphysalis was the predominant tick species (92.72%). Tick positivity for the KFD virus was 4 (5.33%) of 75 pools of ticks tested. Kyasanur forest disease viral RNA was detected from the genera Haemaphysalis and Amblyomma. The KFD virus was detected in 2 of 35 pools (5.71%) of Haemaphysalis spinigera, 1 of 30 pools (3.33%) of Haemaphysalis turturis, and 1 of 3 pools (3.33%) of Amblyomma integrum from the south forest division. The ticks reached their peak density between December and February and then decreased from the end of May. The temperature in the area ranges from 28°C to 30°C, which is suitable for tick survival.

Clinical and Laboratory Diagnostic Features of Kyasanur Forest Disease: A Study From Wayanad, South India

Background

Kyasanur forest disease (KFD), also known as monkey fever, was first recognized in the Shimoga district of Karnataka, India, in 1957. This study was conceived to address the paucity of medical literature on KFD, to describe the clinical and laboratory features of real-time reverse-transcriptase-polymerase chain reaction (rRT-PCR) confirmed cases of KFD, and to detect any change in the clinical picture and presentation of the disease over the last 30 years.

Aim

The study sought to document the clinical and laboratory features of Kyasanur forest disease (KFD), a tick-borne arboviral disease, now emerging in many parts of southern India.

Material and methods

This was a retrospective study using secondary data of patients with real-time reverse transcription-polymerase chain reaction (rRT-PCR)-confirmed KFD in a secondary care hospital in Wayanad, Kerala, India.

Results

Sixty rRT-PCR-proven KFD patients were included in the study. Commonly noted clinical symptoms were fever (98%), headache (80%), body ache (86%), vomiting (61%), and prostration (83%). Relative bradycardia, hypotension (45%), and oral lesions (23%) were the frequent physical signs. The median total leukocyte count and median platelet count at admission were 2600 per μL and 1.62 per μL, respectively. The median erythrocyte sedimentation rate was 10 mm/hr. Urinary sediments and albuminuria were seen in 66% and 60% respectively. The major complications observed were neurological complications (23%), bleeding manifestations (20%), and persistent shock (20%). The common neurological complications were seizures, altered sensorium, aseptic meningitis, and focal neurological deficits. The case fatality rate in the study was 6.7%.

Conclusions

The clinical picture of a prostrating viral syndrome in an epidemiological setting of KFD with marked leucopenia, moderate thrombocytopenia, low erythrocyte sedimentation rate (ESR), albuminuria, urinary sediments, and moderately elevated transaminases help in making an early diagnosis of KFD. Neurological complications in the initial two weeks are associated with poor outcomes.

Kyasanur Forest Disease, is our surveillance system healthy to prevent a larger outbreak? A mixed-method study, Shivamogga, Karnataka, India: 2019

BACKGROUND

Kyasanur Forest disease (KFD) is a tick-borne zoonosis that is endemic in Karnataka. Against the backdrop of the recent geographical expansion of KFD, indicating the inadequacy of policy and surveillance systems, the present study was performed to evaluate the KFD surveillance system in Shivamogga.

METHODS

US Centers for Disease Control and Prevention guidelines for surveillance system evaluation were followed. Nine attributes of the system towards its objectives were evaluated in a mixed study in Shivamogga.

RESULTS

Two of three medical officers and four of six health staff at the institutions visited were found to be untrained in KFD surveillance. Integrated disease surveillance formats did not capture KFD data. Surveillance (tick, monkey, human) was mostly driven by the Health Department. Some of the critical findings of the evaluations were the absence of an animal and entomological surveillance line list, non-standardized reporting formats for human suspects, varying delays in the time-to-test across laboratories (2-16 days), and a lack of systematic data-sharing practices. Significant issues that emerged in the interview were deforestation with a change in ecosystem dynamics, limited diagnostic capacity, non-availability of point-of-care tests, outdated surveillance guidelines, a confusing surveillance perimeter (5 km), non-existing co-ownership among stakeholders, limited vaccine production capacity, and inadequate operational research.

CONCLUSIONS

The system should consider integrating a One Health approach with defined ownership of activities among stakeholders. Revision of the guidelines is mandatory.

The role of religion in One Health. Lessons from the Hanuman langur (Semnopithecus entellus) and other human-non-human primate interactions

Being revered as deities in some religions of the world, non-human primates (NHPs) often share the same space as humans. Such coexistence and interactions with humans, especially around places of worship, have been known to cause significant changes to the behavior and diet of the NHPs in India. Moreover, the interface may also create an opportunity for zoonotic spillover, similar to the majority of newly emerging or re-emerging infections that are found to originate from animal sources. These include the SARS COV-2 virus responsible for the current COVID-19 pandemic; a catastrophic "One Health" crisis; that has highlighted the interconnections between the health of humans, animals, and the environment. Religious beliefs could potentially influence perceptions, actions, and subsequent One Health outcomes resulting from human-animal interaction, which could impact human and animal welfare. Greater insight in this area could provide a better understanding of the complex relationships between humans and NHPs; that may play an important role in mitigating conflict as well as the spillover of zoonotic disease at the human-NHP interface.

Retrospective Study of Kyasanur Forest Disease and Deaths among Nonhuman Primates, India, 1957-2020

Kyasanur Forest disease (KFD) is a tickborne hemorrhagic disease affecting primates along the Western Ghats mountain range in India. Our retrospective study indicated that >3,314 monkey deaths attributed to KFD were reported in KFD-endemic states in India during 1957–2020. These data can help guide surveillance to protect animal and human health.

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.

Update on prevalence and distribution pattern of tick-borne diseases among humans in India: a review

In the present scenario, tick-borne diseases (TBDs) are well known for their negative impacts on humans as well as animal health in India. The reason lies in their increased incidences due to global warming, environmental and ecological changes, and availability of suitable habitats. On a global basis, they are now considered a serious threat to human as well as livestock health. The major tick-borne diseases in India include Kyasanur forest disease (KFD), Crimean-congo hemorrhagic fever (CCHF), Lyme disease (LD), Q fever (also known as coxiellosis), and Rickettsial infections. In recent years, other tick-borne diseases such as Babesiosis, Ganjam virus (GANV), and Bhanja virus (BHAV) infections have also been reported in India. The purpose of this paper is to review the history and the current state of knowledge of tick-borne diseases in the country. The conclusion of this review is extending the requirement of greater efforts in research and government management for the diagnosis and treatment and as well as prevention of these diseases so that tick-borne disease burden should be minimizing in India.

Reviewing the ecological evidence base for management of emerging tropical zoonoses: Kyasanur Forest Disease in India as a case study

Zoonoses disproportionately affect tropical communities and are associated with human modification and use of ecosystems. Effective management is hampered by poor ecological understanding of disease transmission and often focuses on human vaccination or treatment. Better ecological understanding of multi-vector and multi-host transmission, social and environmental factors altering human exposure, might enable a broader suite of management options. Options may include "ecological interventions" that target vectors or hosts and require good knowledge of underlying transmission processes, which may be more effective, economical, and long lasting than conventional approaches. New frameworks identify the hierarchical series of barriers that a pathogen needs to overcome before human spillover occurs and demonstrate how ecological interventions may strengthen these barriers and complement human-focused disease control. We extend these frameworks for vector-borne zoonoses, focusing on Kyasanur Forest Disease Virus (KFDV), a tick-borne, neglected zoonosis affecting poor forest communities in India, involving complex communities of tick and host species. We identify the hierarchical barriers to pathogen transmission targeted by existing management. We show that existing interventions mainly focus on human barriers (via personal protection and vaccination) or at barriers relating to Kyasanur Forest Disease (KFD) vectors (tick control on cattle and at the sites of host (monkey) deaths). We review the validity of existing management guidance for KFD through literature review and interviews with disease managers. Efficacy of interventions was difficult to quantify due to poor empirical understanding of KFDV-vector-host ecology, particularly the role of cattle and monkeys in the disease transmission cycle. Cattle are hypothesised to amplify tick populations. Monkeys may act as sentinels of human infection or are hypothesised to act as amplifying hosts for KFDV, but the spatial scale of risk arising from ticks infected via monkeys versus small mammal reservoirs is unclear. We identified 19 urgent research priorities for refinement of current management strategies or development of ecological interventions targeting vectors and host barriers to prevent disease spillover in the future.

'None of my ancestors ever discussed this disease before!' How disease information shapes adaptive capacity of marginalised rural populations in India

Smallholder farmer and tribal communities are often characterised as marginalised and highly vulnerable to emerging zoonotic diseases due to their relatively poor access to healthcare, worse-off health outcomes, proximity to sources of disease risks, and their social and livelihood organisation. Yet, access to relevant and timely disease information that could strengthen their adaptive capacity remain challenging and poorly characterised in the empirical literature. This paper addresses this gap by exploring the role of disease information in shaping the adaptive capacity of smallholder farmer and tribal groups to Kyasanur Forest Disease (KFD), a tick-borne viral haemorrhagic fever. We carried out household surveys (n = 229) and in-depth interviews (n = 25) in two affected districts-Shimoga and Wayanad-in the Western Ghats region. Our findings suggest that, despite the generally limited awareness about KFD, access to disease information improved households' propensity to implement adaptation strategies relative to households that had no access to it. Of the variety of adaptation strategies implemented, vaccination, avoiding forest visits, wearing of protective clothing and footwear, application of dimethyl phthalate (DMP) oil and income diversification were identified by respondents as important adaptive measures during the outbreak seasons. Even so, we identified significant differences between individuals in exposure to disease information and its contribution to substantive adaptive action. Households reported several barriers to implement adaptation strategies including, lack of disease information, low efficacy of existing vaccine, distrust, religio-cultural sentiments, and livelihood concerns. We also found that informal information sharing presented a promising avenue from a health extension perspective albeit with trade-offs with potential distortion of the messages through misinformation and/or reporting bias. Altogether, our findings stress the importance of contextualising disease information and implementing interventions in a participatory way that sufficiently addresses the social determinants of health in order to bolster households' adaptive capacity to KFD and other neglected endemic zoonoses.

Development and evaluation of reverse transcription loop-mediated isothermal amplification for rapid and real-time detection of Kyasanur forest disease virus

SIGNIFICANCE

Kyasanur forest disease (KFD), a re-emerging tick-borne viral disease, causes severe hemorrhagic fever in humans and nonhuman primates. KFD virus (KFDV) is a member of the genus Flavivirus. KFD is now increasingly reported outside its endemic zone in India. Rapid and specific detection of the KFDV plays a critical role in containment of the outbreak. The diagnosis of KFD currently relies on real-time RT-PCR, nested RT-PCR, end point RT-PCR, and serodiagnostic assay. These assays are tedious, time-consuming, and cannot be used as a routine screening platform.

OBJECTIVE

The present study was aimed to develop a one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for molecular diagnosis of KFD.

DESIGN

The gene amplification reaction was accomplished by incubation at a constant temperature of 63°C for 60min.

RESULTS

The limit of detection of RT-LAMP assay was 10 copies. KFD RT-LAMP assay was successfully evaluated with diverse host samples including humans, monkeys, and tick. The assay correctly picked up different KFD isolates indicating its applicability for divergent strains. Comparative evaluation of RT-LAMP assay with quantitative TaqMan real-time RT-PCR revealed 100% concordance. No cross-reaction with related flavi and other hemorrhagic fever viruses was observed, indicating its high specificity.

CONCLUSION AND RELEVANCE

The RT-LAMP test developed in this study will serve as a rapid, sensitive alternate detection method for KFDV infection and would be useful for high throughput screening of clinical samples in resource limited areas during outbreaks.

Kyasanur Forest Disease and Alkhurma Hemorrhagic Fever Virus-Two Neglected Zoonotic Pathogens

Kyasanur Forest disease virus (KFDV) and Alkhurma hemorrhagic fever virus (AHFV) are tick-borne flaviviruses that cause life-threatening hemorrhagic fever in humans with case fatality rates of 3-5% for KFDV and 1-20% for AHFV, respectively. Both viruses are biosafety level 4 pathogens due to the severity of disease they cause and the lack of effective countermeasures. KFDV was discovered in India and is restricted to parts of the Indian subcontinent, whereas AHFV has been found in Saudi Arabia and Egypt. In recent years, both viruses have spread beyond their original endemic zones and the potential of AHFV to spread through ticks on migratory birds is a public health concern. While there is a vaccine with limited efficacy for KFDV used in India, there is no vaccine for AHFV nor are there any therapeutic concepts to combat infections with these viruses. In this review, we summarize the current knowledge about pathogenesis, vector distribution, virus spread, and infection control. We aim to bring attention to the potential public health threats posed by KFDV and AHFV and highlight the urgent need for the development of effective countermeasures.

Geospatial clustering, seasonal trend and forecasting of Kyasanur Forest Disease in the state of Goa, India, 2015-2018

Introduction

Five states in India are reporting sporadic outbreaks of Kyasanur Forest Disease (KFD). Goa experienced an outbreak of KFD in 2015. It remains as an important differential diagnosis for tropical fever in the endemic regions. Few studies among neighboring two states (Karnataka and Kerala) have described the epidemiological characteristics of KFD. However, there is no study which describes the same among cases in the state of Goa. Hence, we planned to understand the epidemiology (time, place, and person distribution) of the disease including seasonal pattern with forecasting using zero-inflated negative binomial regression and time series models. We also explored geo-spatial clustering of KFD cases in Goa during 2015–2018 which would help design effective intervention to curb its transmission in Goa.

Results

Blood samples of all suspected cases of KFD during 2015 to 2018 were tested using reverse transcriptase-polymerase chain reaction technique. Reports of these results were periodically shared with the state surveillance unit. Records of 448 confirmed cases of KFD available at the State Integrated Disease Surveillance Programme were analyzed. The mean (SD) age of the patients was 41.6 (14.9) years. Of 143 cases with documented travel history, 135 (94.4%) had history of travel to forest for cashew plucking. Two thirds of cases (66.3%) did not receive KFD vaccine prior to the disease. Case fatality rate of 0.9% was reported. Seasonal peaks were observed during January to April, and forecasting demonstrated a peak in cases in the subsequent year also during January–April persisting till May. Around 40 villages located along the Western Ghats had reported KFD, and affected villages continued to report cases in the subsequent years also. Case density-based geographic maps show clustering of cases around the index village.

Conclusion

Most of the confirmed cases did not receive any vaccination. KFD cases in Goa followed a specific seasonal pattern, and clustering of cases occurred in selected villages located in North Goa. Most of the patients who had suffered from the disease had visited the forest for cashew plucking. Planning for public health interventions such as health education and vaccination campaigns should consider these epidemiological features.

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.

Phylogeography of Kyasanur Forest Disease virus in India (1957-2017) reveals evolution and spread in the Western Ghats region

The Kyasanur Forest Disease (KFD) has become a major public health problem in the State of Karnataka, India where the disease was first identified and in Tamil Nadu, Maharashtra, Kerala, and Goa covering the Western Ghats region of India. The incidence of positive cases and distribution of the Kyasanur Forest Disease virus (KFDV) in different geographical regions raises the need to understand the evolution and spatiotemporal transmission dynamics. Phylogeography analysis based on 48 whole genomes (46 from this study) and additionally 28 E-gene sequences of KFDV isolated from different regions spanning the period 1957-2017 was thus undertaken. The mean evolutionary rates based the E-gene was marginally higher than that based on the whole genomes. A subgroup of KFDV strains (2006-2017) differing from the early Karnataka strains (1957-1972) by ~2.76% in their whole genomes and representing spread to different geographical areas diverged around 1980. Dispersal from Karnataka to Goa and Maharashtra was indicated. Maharashtra represented a new source for transmission of KFDV since ~2013. Significant evidence of adaptive evolution at site 123 A/T located in the vicinity of the envelope protein dimer interface may have functional implications. The findings indicate the need to curtail the spread of KFDV by surveillance measures and improved vaccination strategies.

Kyasanur Forest Disease vaccination coverage and its perceived barriers in Goa, India-A mixed methods operational research

Background

Kyasanur Forest Disease (KFD) is a highly infectious viral illness transmitted by infected ticks through contact with monkeys and other forest animals. Till date there is no definite treatment available for KFD. Hence, vaccination is considered to be an important public health intervention to control KFD. This study aimed at estimating the vaccination coverage for primary and booster doses of KFD vaccine and exploring the perceived barriers to vaccination in the affected villages of Goa, India during 2015–18.

Methodology & principal findings

In this explanatory mixed methods study, vaccine coverage was estimated bydata obtained from the KFD vaccination registers maintained at the health centers catering to the KFD affected villages. To understand the barriers to vaccination,key informant interviews were conducted among implementing health officers, medical officers and nurses involved in vaccination. Perceptions of vaccinees and community members were studied through in-depth interviews and focus group discussions.

Out of the 35,500 targeted population (6–65 years)for KFD vaccination, 32% received one dose and 13.2% received two doses. The coverage for first booster and annual booster was 4.9% and 0.5% respectively. The drop out from first to second and third doses was 57% and 85% respectively. 69% of doses were delivered during community outreach programmes and remaining at health facilities. Inadequate vaccine stock, inappropriate timing of vaccination campaign, lack of awareness and misconceptions related to indications of vaccines, travel distance for follow up doses given at community health centre and pain due to injection were perceived as reasons for poor vaccination coverage.

Conclusions

KFD vaccination coverage was poor in the villages affected by KFD in Goa. Both left-out and drop-out phenomena were observed in KFD vaccination. Vaccine implementation plan has to consider suitable time for the local people, maintain adequate vaccine stock and encourage community-based vaccination campaigns instead of facility-based to achieve optimal vaccine coverage.

Kyasanur Forest Disease in India: innovative options for intervention

Kyasanur Forest Disease (KFD) is a tick-borne hemorrhagic fever of human, caused by Kyasanur forest disease virus (KFDV) in India. The tick, Haemaphysalis spinigera, has been incriminated as the vector of KFDV. In human, KFD clinically presents with high fever, frontal headache, and severe myalgia, followed by bleeding from the nasal cavity, throat, gingivae, and in some cases, gastrointestinal tract. The mortality rate in KFDV infected cases is estimated to be 3-10%. Monkeys infected with the virus also develop the disease and die. Though the incidence of KFD was found to be confined only to the sylvatic area of Shimoga district in Karnataka state in India during 1967, recent reports indicate its expanding potential to the neighboring states such as Kerala, Tamil Nadu, and Goa. The administration of an indigenous, inactivated tissue culture vaccine was found to drastically decrease the percentage of incidence; however, the recurrence of KFD in vaccinated subjects warrants innovative strategies for effective control of the infection. The present communication proposes and discusses innovative intervention strategies for the effective prevention and control of KFD in India.

Durch Zecken übertragbare Erkrankungen

Zecken sind Überträger einer Vielzahl humanpathogener Krankheitserreger mit einer großen Bandbreite klinischer Symptome. Das Verbreitungsgebiet der einzelnen Erreger ist vom Vorkommen der Vektoren und Wirte abhängig. Aufgrund verschiedener Faktoren ist es in den letzten Jahren zum Teil zu einer Ausdehnung der Endemiegebiete gekommen. Am weitesten verbreitet sind Zecken-übertragene Rickettsiosen, welche v.a. in der Reisemedizin eine Rolle spielen. Die häufigsten Zecken-übertragbaren Erkrankungen in Deutschland und Europa sind Lyme-Borreliose und Frühsommer-Meningoenzephalitis (FSME). Meist verlaufen die Infektionen mild oder sind — im Falle bakterieller Infektionen — gut behandelbar. Die wichtigsten präventiven Maßnahmen bei Aufenthalten in einem Risikogebiet sind der Schutz vor Zeckenstichen und im Falle der FSME die sehr gut wirksame Impfung.

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.

Historical Expansion of Kyasanur Forest Disease in India From 1957 to 2017: A Retrospective Analysis

A highly infectious tick-borne virus causes Kyasanur Forest disease (KFD), which has been expanding in recent decades in India. Current studies do not provide an updated understanding of the disease trends and its expansion in India. We address this gap in the literature through a detailed review to reveal the annual historic expansion of KFD cases across the span of years from 1957 to 2017. In addition, we explore the factors that may have led to the geographic expansion of KFD. The annual numbers of cases of KFD among humans are estimated using peer-reviewed journal articles, Pro-MED database, historical and archived newspapers, and government reports, technical reports, publications, and medical websites. From 1957 to 2017, there were an estimated 9,594 cases of KFD within 16 districts in India. The most significant human outbreaks of the disease were in the years 1957-1958 (681 cases), 1983-1984 (2,589 cases), 2002-2003 (1,562 cases), and 2016-2017 (809 cases). In 2015, KFD appeared in Goa. In 2016, new cases emerged in Belgaum, a district in Karnataka state, and in the Sindhudurg district in Maharashtra state. The processes by which KFD persists and spreads are not clear, but demographic, socioeconomic, political, and environmental factors seem to play a role.

Tick-Borne Flaviviruses, with a Focus on Powassan Virus

The tick-borne pathogen Powassan virus is a rare cause of encephalitis in North America and the Russian Far East. The number of documented cases described since the discovery of Powassan virus in 1958 may be <150, although detection of cases has increased over the past decade. In the United States, the incidence of Powassan virus infections expanded from the estimated 1 case per year prior to 2005 to 10 cases per year during the subsequent decade. The increased detection rate may be associated with several factors, including enhanced surveillance, the availability of improved laboratory diagnostic methods, the expansion of the vector population, and, perhaps, altered human activities that lead to more exposure. Nonetheless, it remains unclear whether Powassan virus is indeed an emerging threat or if enzootic cycles in nature remain more-or-less stable with periodic fluctuations of host and vector population sizes. Despite the low disease incidence, the approximately 10% to 15% case fatality rate of neuroinvasive Powassan virus infection and the temporary or prolonged sequelae in >50% of survivors make Powassan virus a medical concern requiring the attention of public health authorities and clinicians. The medical importance of Powassan virus justifies more research on developing specific and effective treatments and prevention and control measures.

Epidemiology, Pathogenesis, and Control of a Tick-Borne Disease- Kyasanur Forest Disease: Current Status and Future Directions

In South Asia, Haemaphysalis spinigera tick transmits Kyasanur Forest Disease Virus (KFDV), a flavivirus that causes severe hemorrhagic fever with neurological manifestations such as mental disturbances, severe headache, tremors, and vision deficits in infected human beings with a fatality rate of 3-10%. The disease was first reported in March 1957 from Kyasanur forest of Karnataka (India) from sick and dying monkeys. Since then, between 400 and 500 humans cases per year have been recorded; monkeys and small mammals are common hosts of this virus. KFDV can cause epizootics with high fatality in primates and is a level-4 virus according to the international biosafety rules. The density of tick vectors in a given year correlates with the incidence of human disease. The virus is a positive strand RNA virus and its genome was discovered to code for one polyprotein that is cleaved post-translationally into 3 structural proteins (Capsid protein, Envelope Glycoprotein M and Envelope Glycoprotein E) and 7 non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5). KFDV has a high degree of sequence homology with most members of the TBEV serocomplex. Alkhurma virus is a KFDV variant sharing a sequence similarity of 97%. KFDV is classified as a NIAID Category C priority pathogen due to its extreme pathogenicity and lack of US FDA approved vaccines and therapeutics; also, the infectious dose is currently unknown for KFD. In India, formalin-inactivated KFDV vaccine produced in chick embryo fibroblast is being used. Nevertheless, further efforts are required to enhance its long-term efficacy. KFDV remains an understudied virus and there remains a lack of insight into its pathogenesis; moreover, specific treatment to the disease is not available to date. Environmental and climatic factors involved in disseminating Kyasanur Forest Disease are required to be fully explored. There should be a mapping of endemic areas and cross-border veterinary surveillance needs to be developed in high-risk regions. The involvement of both animal and health sector is pivotal for circumscribing the spread of this disease to new areas.

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.

Development of single step RT-PCR for detection of Kyasanur forest disease virus from clinical samples

Background

Kyasanur Forest Disease (KFD), a tick borne flavivirus, which was earlier endemic to Karnataka state, India, has been confirmed and detected from neighboring states of Tamil Nadu, Maharashtra, Goa and Kerala states in India. Increased human and vector surveillance therefore becomes essential for the identification of KFD affected regions and control of further spread of the disease. Currently, available KFD detection assays include realtime RT-PCR and nested RT-PCR assays. Here we describe the development of a sensitive single step RT-PCR assay for the detection of KFD viral RNA. This can be easily used in any BSL-2 laboratory for screening of KFD suspected cases or for differential diagnosis of viral hemorrhagic fever panel.

Method

Three primer sets were designed and checked for sensitivity using known dilutions of KFD viral RNA (Ranging from 10⁶ copies to 10 copies). The primer set (2) was found to be most sensitive was selected and tested for specificity for Kyasanur forest disease virus (KFDV) by testing against zika, dengue, chikungunya, crimean congo hemorrhagic fever (CCHF), yellow fever, japanese encephalitis (JE) and west nile viruses. A total of 104 samples (human, monkey and tick positive and negative samples) were tested using this assay.

Result

No false positive or false negative results were seen for human, monkey or tick samples. The assay was specific for KFD and could detect upto 100 copies of KFD viral RNA.

Discussion and conclusion

The previously published sensitive real time RT-PCR assay requires higher cost in terms of reagents and machine setup and technical expertise has been the primary reason for development of this assay. A single step RT-PCR is relatively easy to perform and more cost effective than real time RT-PCR in smaller setups in the absence of Biosafety Level-3 facility. This study reports the development and optimization of single step RT-PCR assay which is more sensitive and less time-consuming than nested RT-PCR and cost effective for rapid diagnosis of KFD viral RNA.

Emerging Tick-Borne Viruses in the Twenty-First Century

Ticks, as a group, are second only to mosquitoes as vectors of pathogens to humans and are the primary vector for pathogens of livestock, companion animals, and wildlife. The role of ticks in the transmission of viruses has been known for over 100 years and yet new pathogenic viruses are still being detected and known viruses are continually spreading to new geographic locations. Partly as a result of their novelty, tick-virus interactions are at an early stage in understanding. For some viruses, even the principal tick-vector is not known. It is likely that tick-borne viruses will continue to emerge and challenge public and veterinary health long into the twenty-first century. However, studies focusing on tick saliva, a critical component of tick feeding, virus transmission, and a target for control of ticks and tick-borne diseases, point toward solutions to emerging viruses. The aim of this review is to describe some currently emerging tick-borne diseases, their causative viruses, and to discuss research on virus-tick interactions. Through focus on this area, future protein targets for intervention and vaccine development may be identified.

The Geographic Distribution of Ixodes scapularis (Acari: Ixodidae) Revisited: The Importance of Assumptions About Error Balance

The black-legged tick, Ixodes scapularis Say, is the primary vector of Borrelia burgdorferi, a spirochete that causes Lyme disease, in eastern North America. Lyme disease risk has generally been considered to be focused in the Northeast and the northern Midwest in the United States, yet the distribution of the vector extends considerably more broadly. A recent analysis of the distribution of the species using ecological niche modeling approaches painted an odd biogeographic picture, in which the species is distributed in a "rimming" distribution across the northern Midwest and Northeast, and along the Atlantic and Gulf coasts of the eastern United States, but not broadly in the interior of eastern North America. Here, we reanalyze the situation for this species, and demonstrate that the distribution estimated in the previous study was a consequence of assumptions about relative weights applied to different error types. A more appropriate error weighting scheme for niche modeling analyses, in which omission error is prioritized over commission error, shows a simpler distribution, in which the species ranges continuously across eastern North America; this distributional pattern is supported by independent occurrence data from the eastern Great Plains, in Kansas. We discuss implications for public health planning and intervention across the region, as well as for developing effective and predictive maps of vector distributions and pathogen transmission 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.

Limited Effects of Type I Interferons on Kyasanur Forest Disease Virus in Cell Culture

BACKGROUND

The tick-borne flavivirus, Kyasanur Forest disease virus (KFDV) causes seasonal infections and periodic outbreaks in south-west India. The current vaccine offers poor protection with reported issues of coverage and immunogenicity. Since there are no approved prophylactic therapeutics for KFDV, type I IFN-α/β subtypes were assessed for antiviral potency against KFDV in cell culture.

METHODOLOGY/PRINCIPAL FINDINGS

The continued passage of KFDV-infected cells with re-administered IFN-α2a treatment did not eliminate KFDV and had little effect on infectious particle production whereas the IFN-sensitive, green fluorescent protein-expressing vesicular stomatitis virus (VSV-GFP) infection was controlled. Further evaluation of the other IFN-α/β subtypes versus KFDV infection indicated that single treatments of either IFN-αWA and IFN-αΚ appeared to be more effective than IFN-α2a at reducing KFDV titres. Concentration-dependent analysis of these IFN-α/β subtypes revealed that regardless of subtype, low concentrations of IFN were able to limit cytopathic effects (CPE), while significantly higher concentrations were needed for inhibition of virion release. Furthermore, expression of the KFDV NS5 in cell culture before IFN addition enabled VSV-GFP to overcome the effects of IFN-α/β signalling, producing a robust infection.

CONCLUSIONS/SIGNIFICANCE

Treatment of cell culture with IFN does not appear to be suitable for KFDV eradication and the assay used for such studies should be carefully considered. Further, it appears that the NS5 protein is sufficient to permit KFDV to bypass the antiviral properties of IFN. We suggest that other prophylactic therapeutics should be evaluated in place of IFN for treatment of individuals with KFDV disease.

Development of a subgenomic clone system for Kyasanur Forest disease virus

Emerging tropical viruses pose an increasing threat to public health because social, economic and environmental factors such as global trade and deforestation allow for their migration into previously unexposed populations and ecological niches. Among such viruses, Kyasanur Forest disease virus (KFDV) deserves particular recognition because it causes hemorrhagic fever. This work describes the completion of an antiviral testing platform (subgenomic system) for KFDV that could be used to quickly and safely screen compounds capable of inhibiting KFDV replication without the requirement for high containment, as the structural genes have been replaced with a luciferase reporter gene precluding the generation of infectious particles. The coordination of KFDV kinetics with the replication characteristics of the subgenomic system has provided additional insight into the timing of flavivirus replication events, as the genetically engineered KFDV genome began replication as early as 2h post cellular entry. Possession of such antiviral testing platforms by public health agencies should accelerate the testing of antiviral drugs against emerging or recently emerged viruses mitigating the effects of their disease and transmission.