The viral tick talks: how vectors and wildlife shape Kyasanur forest disease ecology.

A preliminary ecological profile of Kyasanur Forest disease virus hosts among the mammalian wildlife of the Western Ghats, India

Kyasanur Forest Disease Virus (KFDV), discovered in 1957, is a member of the tick-borne encephalitis virus (TBEV) complex. Diseases caused by members of the TBEV complex occur in many parts of the world. KFDV produces a hemorrhagic fever in humans in South India and fatal illnesses in both species of monkeys in the area, the black faced langur (Presbytis entellus) and the bonnet macaque (Macaca radiata). Experimental infection of the langur and the bonnet macaque with early mouse passage KFDV strain P9605 resulted in a viremia of up to 11 days duration, peak viremia titers as high as 10 9, and death in 82 = 100% of the animals. Prolonged passage of the KFDV strain P9605 in monkey kidney tissue culture resulted in a markedly reduced virulence of the virus for both species; peak viremia titers in monkeys decreased by 2.5 to 4.0 log LD 50 (p= 0.001), and the mortality decreased to 10% (p= 0.001). In challenge experiments, monkeys previously infected with tissue-culture-adapted KFDV, or with the related Langat virus from Malaysia, were fully protected against virulent KFDV. These studies in non-human primates lend support to the idea that a live virus vaccine from a member of the TBEV complex may be broadly protective against infections by other members of the TBEV complex.

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.

Several viral hemorrhagic fever (VHF) diseases affect large populations in India. Among these, Dengue is the most common endemic mosquito-borne VHF disease. Two other common VHF diseases are tick-borne: Kyasanur Forest disease (KFD) and Crimean Congo hemorrhagic fever (CCHF). CCHF was detected in India recently. KFD virus has a wide range of tick vector species and involves several mammalian hosts. Until 2011, KFD was seen only in southern India, but recently its presence was confirmed in the Western Ghats region, including Karnataka, Tamil Nadu, Kerala, Goa and Maharashtra states. This discovery has raised suspicion whether it existed earlier in these areas. Although, the risk of human-to-human transmission of this disease is very low, it is important to consider the high prevalence of the vectors namely ticks; small mammals, monkeys, and domestic animals that are carriers of infected ticks as well as deforestation. Knowledge of KFD pathogenicity, improved and cost-effective diagnostics, laboratory networks, increased awareness of travelers to forested areas, and surveillance are needed to reduce fatality. The use of standard biosafety practices in handling the virus in the laboratory and in associated field work reduces the risk associated with infection.

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

Kyasanur Forest Disease (KFD) is a viral haemorrhagic fever, transmitted to humans and other hosts by a tick vector of genus Haemaphysalis. It affects 400-500 people annually in the Western Ghats region of India through spring to summer season. To understand the species composition, distribution, and abundance of Haemaphysalis ticks in endemic taluks (sub-districts) of India, a surveillance for ticks was conducted between October 2017 and January 2018. In total 105 sites were selected based on grid sampling from five taluks representing five KFD endemic states in south India. A sum of 8373 ticks were collected by using standard flagging method. The study showed a wide distribution of host seeking tick species among the selected taluks, wherein Haemaphysalis spinigera was predominant in 3/5 taluks, Haemaphysalis bispinosa in 1/5 taluks, and both the species in 1/5 taluks. Further, the H. spinigera abundance was categorised and compared with the incidence of human cases during the same season. The grids with very high and high H. spinigera abundance had 70% of the 205 human cases reported. This method of tick surveillance could be efficiently used as a standard model for KFD transmission risk assessment and prediction of impending outbreaks.

The limitations of the current vaccination strategy for the Kyasanur Forest Disease virus (KFDV) underscore the critical need for effective antiviral treatments, highlighting the crucial importance of exploring novel therapeutic approaches through in silico drug design. Kyasanur Forest Disease, caused by KFDV, is a tick-borne disease with a mortality of 3-5% and an annual incidence of 400 to 500 cases. In the early stage of infection, the envelope protein plays a crucial role by facilitating host-virus interactions. The objective of this research is to develop effective antivirals targeting the envelope protein to disrupt the virus-host interaction. In line with this, the 3D structure of the envelope protein was modeled and refined through molecular modeling techniques, and subsequently, ligands were designed via de novo design and pharmacophore screening, yielding 12 potential hits followed by ADMET analysis. The top five candidates underwent geometry optimization and molecular docking. Notably, compounds L4 (SA28) and L3 (CNP0247967) are predicted to have significant binding affinities of -8.91 and -7.58 kcal/mol, respectively, toward the envelope protein, based on computational models. Both compounds demonstrated stability during 200 ns molecular dynamics simulations, and the MM-GBSA binding free-energy values were -85.26 ± 4.63 kcal/mol and -66.60 ± 2.92 kcal/mol for the envelope protein L3 and L4 complexes, respectively. Based on the computational prediction, it is suggested that both compounds have potential as drug candidates for controlling host-virus interactions by targeting the envelope protein. Further validation through in-vitro assays would complement the findings of the present in silico investigations.

Emerging zoonotic viral diseases pose significant public health challenges due to their high fatality rates, potential for widespread outbreaks, and profound socioeconomic impact. Human, animal, and environmental health interconnectedness highlights the need for a collaborative One Health (OH) approach to control and prevent these diseases. With its diverse ecosystems and rapid urbanization, India has witnessed several major zoonotic outbreaks over the past two decades, including Nipah virus, Kyasanur Forest Disease (KFD), H1N1 influenza, and the global COVID-19 pandemic. These outbreaks underscore the urgent need for integrated surveillance systems, early detection strategies, and sustainable interventions to mitigate future risks. Contributing factors such as deforestation, climate change, unregulated wildlife trade, and intensive farming practices exacerbate the spread of zoonotic diseases. This manuscript emphasizes the importance of a multidisciplinary OH approach, drawing on evidence-based strategies for disease surveillance, vaccination, vector control, and community engagement. By addressing these challenges through coordinated efforts, India can strengthen its preparedness and response to emerging zoonotic viral diseases while promoting public and ecological health.

Oropouche virus (OROV) is an emerging arbovirus primarily transmitted by biting midges and is increasingly recognized as a public health threat in Central and South America. With over 11,000 confirmed cases reported in 2024, a ten-fold increase from the previous year, its transmission dynamics and true burden remain poorly understood due to diagnostic challenges and fragmented surveillance systems. This systematic review and meta-analysis (SRMA) synthesizes OROV prevalence data in humans and summarizes the available data for vectors and animal hosts sampled between 2000 and 2024 to provide updated estimates and identify key surveillance gaps. We systematically searched Web of Science, PubMed, Embase, Medline, and LILACS for OROV seroprevalence and viral prevalence studies in human, insect, and animal populations, published up to September 12, 2024. The review protocol was registered with PROSPERO (CRD42024551000). Studies were extracted in duplicate, and data were meta-analyzed using generalized linear mixed-effects models. Risk of bias was appraised using a modified Joanna Briggs Institute checklist. We included 71 articles reporting serological or viral prevalence of OROV across nine countries. Between 2000-2024, pooled human seroprevalence among individuals with febrile illness or suspected of Oropouche infection was 12.6% [95% CI 5.3-26.9%] across four South American countries and seroprevalence of 1.1% [95% CI 0.5-2.3%] was observed in asymptomatic groups. Viral prevalence among individuals with febrile illness or suspected of Oropouche infection was 1.5% [0.8-3.0%] across seven South American countries and Haiti. Most studies used convenience sampling and RT-PCR or hemagglutination assays. In vector populations, positive OROV prevalence in Aedes aegypti and Culex quinquefasciatus was reported in two of 18 sources, while 10.0% and 7.5% animal host prevalence was reported in dogs and cattle, respectively. We found high risk of bias in 11.3% of studies in our critical appraisal, with most animal, human, and vector studies falling in the moderate risk of bias range. Despite rising numbers of OROV reported cases, prevalence estimates remain limited by sparse surveillance and variable methodology. This review highlights the urgent need for standardized serological assays, community-based studies, and expanded surveillance in animal and vector reservoirs. A One Health approach is essential to monitor OROV transmission and inform regional preparedness efforts.

Copyright: © 2013 Shahein YE. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Over the past few years, the science of developing vaccines have had, and continue to prevent diseases. Veterinary vaccines have a major role in reducing animal suffering, protection of animal health and enhance efficient animal productivity. Ticks are considered among the most important disease transmitting vectors second to mosquitoes. Tick borne diseases affect both human and livestock animals in many tropical and subtropical areas [1,2]. Ticks transmit several viral infections, bacterial and protozoan diseases causing Encephalitis, Crimean-Congo Hemorrhagic fever, Kyasanur forest disease, Lyme disease, Rocky Mountain spotted fever, monocytic and granulocytic ehrlichiosis, and bebesiosis.

The present study is the first report on ticks infesting domestic animals of the tribal communities and wildlife in Aralam Wildlife Sanctuary, Kerala, India. Questing ticks in the sanctuary were collected through dragging methods and hand collection from domestic animals was used to collect feeding ticks. Among the total 3,081 ticks collected, 2,350 questing ticks were obtained from the forest floor, and 731 ticks were recorded from 40 different domestic animals belonging to four species. The present collection recorded eight Haemaphysalis species: Ha. spinigera, Ha. leachii, Ha. shimoga, Ha. kinneari, Ha. kyasanurensis, Ha. turturis, Ha. bispinosa, Ha. intermedia and one Amblyomma species: Am. integrum from the sanctuary. Whereas five Haemaphysalis species: Ha. bispinosa, Ha. intermedia, Ha. shimoga, Ha. spinigera, Ha. turturis and four Rhipicephalus species: Rh. sanguineus, Rh. haemaphysaloides, Rh. microplus and Rh. annulatus were reported from domestic animals. High abundance of Kyasanur Forest Disease (KFD) vectors, Ha. spinigera and Ha. turturis have been documented from the sanctuary. Relative abundance of Ha. bispinosa was significantly higher in all the domestic animals examined. Tick infestation rate was higher in goats followed by cows, dogs, and cats. Whereas the species richness of ticks was highest in cows and lowest in cats.

The present study was carried out to determine the diversity, distribution and vegetative structure of mangroves of the Andaman and Nicobar Islands (ANI). The results suggest that mangroves of the ANI consist of 38 mangrove species belonging to 12 families and 19 genera, which includes 4 hybrids and 34 species. In other words, about 50% of the global mangrove species are present in ANI. Andaman Islands have 35 species and Nicobar Islands have 21 mangrove species. The average tree density in ANI is 1746/per hectare and varies from 487 to 2383 per hectare. The Shannon diversity index for the whole ANI is 2.94 and Simpson index is 0.07. Family Rhizophoraceae constitutes an important vegetative component in the mangroves of the ANI followed by Acanthaceae, Lythraceae and Malvaceae. Rhizophora spp. constitutes 19% of the Important Value Index (IVI) and R. apiculata is dominant in ANI. Among the eight forest divisions, mangrove diversity is high in South Andaman (30 species) followed by Middle Andaman (28), Mayabunder (25), Diglipur (25), Nicobar (21), Little Andaman (20), Havelock (20) and Baratang (20). The average mangrove plant density and Shannon diversity index (H’) is high in Middle Andaman (2101/hectare; H’ = 2.93). Species richness index (d’) is high in South Andaman (3.32). Evenness index (J’) is high in Little Andaman (0.92). Simpson dominance index (D) ranged between 0.07–0.1, and this agrees with the high diversity in mangroves of ANI. In all the divisions Rhizophora spp. constitutes a major vegetative component except, Diglipur and Nicobar. In Diglipur Bruguiera spp. are dominant, while in Nicobar Sonneratia spp. are dominant. The low similarity value of the Nicobar division with other divisions indicates the difference in floristic structure of mangroves of the Andaman Islands and Nicobar Islands. The present study also indicates that mangrove of ANI are more diverse in its species composition than the other mangrove habitats in India.

In this study, we aimed to document the run-up and inundation of recent tsunamis and loss of life in the December 26, 2004, tsunami in the Andaman and Nicobar Islands. An estimated 1925 people lost their lives and 5555 were reported missing in the Andaman and Nicobar Islands because of the tsunami. The Nicobar group of Islands—namely Great Nicobar, Katchall, Teressa, Nancowry, Trinkat, Car Nicobar, and others—were severely affected by tsunami because they were close to the epicentre. The effect on the Andaman Islands was less severe because of the island's geometry and topography. Because the settlements in the South Andaman Islands are largely confined to sheltered areas like bays that are far from the coast, and more importantly, in elevated areas (except for certain low-elevation, far inland locations like the Sippighat area) there was almost no loss of life. However, damage to property, especially fishing vessels, was high in most of the area, where seawater inundated the land completely. This field survey was conducted at 26 sites; the Little Andaman passenger jetty area recorded the highest run-up of 17.26 m, and the Chidiyatopu area had the highest inundation at 500 m. Furthermore, this survey also supports the assertion that the low-lying areas of Little Andaman were severely affected by the tsunami waves because of their gradual elevation increase.

The mangroves of the Andaman and Nicobar Islands (ANI) are recognized as the best in the country in terms of density and growth. However, considerable disparities still exist in the species composition and classification of mangrove species in the ANI. Further, taxonomical identity and occurrence of certain mangrove species in the ANI remain imprecise. Considering these facts, the present study was carried out to provide an updated checklist of true mangrove species of the ANI based on the extensive field surveys and perusal of the existing literature. Surveys were carried out in eight regions of the ANI and in each region, specific sites were selected based on representativeness, importance, and accessibility. Altogether, 51 sites were surveyed during 2009–2014. The results show that the mangroves of the ANI consist of 38 true mangrove species belonging to 13 families and 19 genera, which account for about 50 % of the global true mangrove species. The Andaman Islands have 35 and the Nicobar Islands have 21 true mangrove species. Among the eight regions, the mangrove diversity is high in South Andaman, followed by Middle Andaman, Mayabunder, Diglipur, Nicobar, Little Andaman, Havelock, and Baratang. Given their limited geographical area, the high similarity index values between the regions (>0.6) indicate the homogenous nature of mangrove diversity in the ANI and absence of impassable dispersal barriers. The Nicobar region exhibited low similarity with other regions (0.61–0.69). The changes in species numbers compared to earlier studies could mainly be attributed to the lack of extensive field survey in the past. Thus, periodical information on the extent and status of mangroves in the islands is imperative not only to improve our understanding of phytogeography, but also for better management and conservation.

Among the myxozoan parasites, the genus Myxobolus is considered as the emerging parasite in freshwater aquaculture. In the present study, a disease outbreak associated with mass mortality was investigated in a carp farm located at North and Middle Andaman district of Andaman and Nicobar Islands. The affected rohu fry exhibited the clinical signs such as lethargic movement, dark body colouration, loss of appetite, excess mucus secretion, 1-2 mm multifocal white nodules on the body surface and skeletal deformities including spinal curvatures. Molecular characterization using 18S rRNA along with clinical signs identified the causative agent as muscle infecting Myxobolus sp. (GenBank accession number MK128509) which showed 95.45% identity with Myxobolus musculi and 95.23% identity with Myxobolus pseudodispar. Genetic distance and phylogenetic tree analysis were performed to elucidate the relationship between the Myxobolus sp. obtained in the present study and the members of other congeners. This investigation serves as the first report of Myxobolus sp. outbreak from Andaman and Nicobar Islands and also reiterates the need for implementation of strict biosecurity measures to preserve the freshwater aquatic fauna of these Islands.