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The distribution of Daboia russelii. The Indian subcontinent distribution is not as continuous as the stylized diagram suggests (particularly in the Ganges delta). In the inset of the Lesser Sundas, there are records from East Java (EJ), Komodo (K), Flores (F), Solor (S), Adonara (A) and Lembata (L).
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The Russell's viper complex has a patchy (relict) distribution over large areas of Asia from Pakistan to Taiwan and the Lesser Sunda islands. In many areas it is the primary cause of snakebite mortality, and hence a serious medical problem. A multigene mitochondrial gene tree, supported by multivariate morphometry and basic colour pattern, suggests...
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Citations
... Epidemiological studies have identified Russell's viper (Daboia russelii) as being the main perpetrator responsible for most bites (Vaiyapuri et al., 2013;Samuel et al., 2020). The clinical manifestations of Russell's viper envenomations display significant variations (Thorpe et al., 2007;Adhikari et al., 2019), while most patients manifest typical features, predominantly composed of local tissue damage, coagulopathies, nephrotoxicity and neurotoxicity, other victims also present various rare pathological complications such as Wunderlich syndrome (spontaneous non-traumatic renal haemorrhage) (Senthilkumaran et al., 2022a), priapism (prolonged penile erection) (Senthilkumaran et al., 2021b), salivary calculus development in the salivary glands (Arathisenthil et al., 2022) and splenic rupture (Senthilkumaran et al., 2021a). A better understanding and broader knowledge surrounding the clinical manifestations of SBE in patients is crucial for medical practitioners to identify such rare complications and mitigate unfavourable outcomes. ...
The clinical management of snakebite envenomation (SBE) is challenging in many tropical and subtropical regions of developing countries due to the complex clinical manifestations and inadequate medical infrastructure. Some venomous snakes, such as the Indian Russell's viper (Daboia russelii) cause a wide range of rare complications in addition to their classical envenomation effects. In general, these uncommon complications are often misdiagnosed or not treated promptly due to a lack of awareness about these conditions. Thus, it is critical to report such complications to draw the attention of the healthcare and research communities to improve the clinical management and scientific research of SBE, respectively. Here, we report bilateral adrenal and pituitary haemorrhages in an SBE patient following a bite by Russell's viper in India. The initial symptoms included gum bleeding, swelling, axillary lymphadenopathy and clotting abnormality. Despite the administration of antivenom, the patient presented palpitation, nausea, and abdominal pain, which were not recovered by combinational therapy with epinephrine and dexamethasone. Further infusion of antivenom did not address these issues and the patient displayed persistent hypotension, hypoglycaemia and hyperkalaemia suggesting an adrenal crisis. Inadequate secretion of corticosteroids was confirmed by laboratory tests, and imaging investigations revealed haemorrhages in both the adrenal and pituitary glands. The patient made a full recovery after treatment with hydrocortisone and thyroxine. This report adds to the growing evidence of rare complications induced by Russell's viper envenomations and it provides relevant guidance to diagnose and treat such complications in SBE victims.
... Moreover, recent phylogeographical and molecular studies have refined our understanding of cryptic speciation across biogeographic boundaries or within biogeographic regions 15,16 , and even propounded the suitability of reptiles in particular as biogeographic indicators 17,18 . Recent studies focussing on widespread reptilian species have also established the existence of previously unnoticed cryptic diversity, including in lizards 19-22 and snakes [23][24][25][26][27][28][29][30] . ...
The banded krait, Bungarusfasciatus is a widespread elapid snake, likely to comprise several distinct species in different geographic regions of Asia. Therefore, based on molecular phylogenetics and comparative morphology data, we present an overview of the systematic composition of the species to delimit potential biogeographic boundaries. Our phylogenetic analyses, based on four mitochondrial genes, reveal the existence of at least three evolutionary lineages within B.fasciatus, corresponding to Indo-Myanmar, Sundaic and eastern Asian lineages. We are convinced that there are at least three taxonomic entities within the nomen B.fasciatus and restrict the distribution of B.fasciatus sensu stricto to the Indo-Myanmar region. We also provide additional natural history data of the taxon from eastern India. Finally, we advocate further studies to establish the degree of reproductive isolation among these diverging evolutionary lineages and to reassess the systematic status of this species complex especially the Sundaic and eastern Asian lineages.
... The Russell's viper (Daboia siamensis) has a vast but disjointed distribution across many regions of South and South-East Asia. It is found in parts of Pakistan, India, Bangladesh and Sri Lanka and, further east, in Taiwan, Thailand, Indonesia and Mainland China [1,2]. Across this distribution, D. siamensis is responsible for a large number of envenomings, which can result in marked local and systemic injuries in envenomed humans [3][4][5][6][7]. ...
The venom of the Russell’s viper (Daboia siamensis) contains neurotoxic and myotoxic phospholipase A2 toxins which can cause irreversible damage to motor nerve terminals. Due to the time delay between envenoming and antivenom administration, antivenoms may have limited efficacy against some of these venom components. Hence, there is a need for adjunct treatments to circumvent these limitations. In this study, we examined the efficacy of Chinese D. siamensis antivenom alone, and in combination with a PLA2 inhibitor, Varespladib, in reversing the in vitro neuromuscular blockade in the chick biventer cervicis nerve-muscle preparation. Pre-synaptic neurotoxicity and myotoxicity were not reversed by the addition of Chinese D. siamensis antivenom 30 or 60 min after venom (10 µg/mL). The prior addition of Varespladib prevented the neurotoxic and myotoxic activity of venom (10 µg/mL) and was also able to prevent further reductions in neuromuscular block and muscle twitches when added 60 min after venom. The addition of the combination of Varespladib and antivenom 60 min after venom failed to produce further improvements than Varespladib alone. This demonstrates that the window of time in which antivenom remains effective is relatively short compared to Varespladib and small-molecule inhibitors may be effective in abrogating some activities of Chinese D. siamensis venom.
... Genus Vipera is widespread throughout Western and Central Asia. It is a genus in constant revision and recognizes some two dozen species and a number of subspecies (Barbanera et al., 2009;David and Ineich, 1999;Garrigues et al., 2005;Joger et al., 2007;Stümpel and Joger, 2009; Thorpe et al., 2007;Ursenbacher et al., 2008;Wüster, 1998;Wüster et al., 2008). The genus Macrovipera extends from Eastern Europe to Western and Central Asia, as well as Mediterranean Africa (David and Ineich, 1999). ...
As the death rate due to snake bites was differ enormously between different countries, the
study conducted was an extensive of neutralization of lethality of two species of genus Naja,
seven species of genus Vipera, and two species of Macrovipera by using VACSERA equine
antisera. The results showed that polyvalent snake venom antisera from VACSERA (which
was prepared by injection of horses by Cerrastes cerastes, and Echis carinatus) was highly
effective in neutralizing specifically to venom used for immunization and para-specifically to
other species including Naja haje, Naja nigricollis, Vipera palastinae, Vipera xanthina, Vipera
ammodytes, Echis coloratus, Cerastes vipera and Pseudoechis beside Macrovipera species
including Macrovipera lebetina obtuse, Macrovipera lebetina turanica. The present
study was established for whether specific or para-specific neutralization exists, its extent
and the potency of para-specific versus specific neutralization within and between each
genus, leading to wide spread of VACSERA Viper antivenom within the different countries.
... In a similar fashion but in Southeast Asia, Daboia siamensis (Smith, 1917) seems to have experienced phases of range expansion and contraction in response to the complex biogeographical and climatic history of the area, particularly related to variations in aridity and seasonality, in addition to forest isolation and reconnection (Sanders et al., 2006). Currently, Daboia siamensis has a broad but patchy distribution that potentially reflects relicts of a once continuous distribution, with subsequent colonization of continental and oceanic islands (Thorpe et al., 2007). Likewise, in Crotalinae, the Trimeresurus lineage experienced multiple glacial-interglacial cycles and was distributed in forest refuges in the Pliocene, with a later colonization from continental areas to islands in the Pleistocene (Sanders et al., 2006;Woodruff et al., 2010). ...
An understanding of patterns of climatic niche evolution has important implications for ecological and evolutionary theory and conservation planning. However, despite considerable testing, niche evolution studies continue to focus on clade-wide, homogeneous patterns, without considering the potentially complex dynamics (i.e. phylogenetic non-stationarity) along the evolutionary history of a clade. Here, we examine the dynamics of climatic niche evolution in vipers and discuss its implication for their current patterns of diversity and distribution. We use comparative phylogenetic methods and global-scale datasets, including 210 viper species with phylogenetic and climatic data. We find that climatic niche evolution in Viperidae shows an overall pattern of phylogenetic conservatism, but with different dynamics depending on the niche feature (niche breadth or niche position) and the evolutionary history of particular lineages within the family, thus resulting in phylogenetic non-stationarity. Indeed, we find several shifts in niche breadth evolution that were probably influenced by the main geological and environmental changes experienced during the evolutionary history of the family. These results highlight the importance of considering complex patterns of climatic niche evolution and their role in shaping patterns of diversity and distribution.
... Disruption of haemostasis is a ubiquitous and often fatal outcome of D. russelii and D. siamensis envenomings [6][7][8]. Despite this shared pathophysiology, Russell's viper venoms differ extensively between populations, manifesting distinct additional pathologies that respond variably to antivenoms and impact upon therapeutic success [9][10][11]. ...
The snake genus Daboia (Viperidae: Viperinae; Oppel, 1811) contains five species: D. deserti, D. mauritanica, and D. palaestinae, found in Afro-Arabia, and the Russell’s vipers D. russelii and D. siamensis, found in Asia. Russell’s vipers are responsible for a major proportion of the medically important snakebites that occur in the regions they inhabit, and their venoms are notorious for their coagulopathic effects. While widely documented, the extent of venom variation within the Russell’s vipers is poorly characterised, as is the venom activity of other species within the genus. In this study we investigated variation in the haemotoxic activity of Daboia using twelve venoms from all five species, including multiple variants of D. russelii, D. siamensis, and D. palaestinae. We tested the venoms on human plasma using thromboelastography, dose-response coagulometry analyses, and calibrated automated thrombography, and on human fibrinogen by thromboelastography and fibrinogen gels. We assessed activation of blood factors X and prothrombin by the venoms using fluorometry. Variation in venom activity was evident in all experiments. The Asian species D. russelii and D. siamensis and the African species D. mauritanica possessed procoagulant venom, while D. deserti and D. palaestinae were net-anticoagulant. Of the Russell’s vipers, the venom of D. siamensis from Myanmar was most toxic and D. russelli of Sri Lanka the least. Activation of both factor X and prothrombin was evident by all venoms, though at differential levels. Fibrinogenolytic activity varied extensively throughout the genus and followed no phylogenetic trends. This venom variability underpins one of the many challenges facing treatment of Daboia snakebite envenoming. Comprehensive analyses of available antivenoms in neutralising these variable venom activities are therefore of utmost importance.
... In some instances, phylogenetic relationships can successfully predict clinical syndromes (e.g., Lesser Antillean Bothrops; Wüster et al., [2002]). In other cases, clinically relevant geographic variation in venom composition exists within species, independent of phylogeny (e.g., Thorpe et al., 2007;Oh et al., 2021) and even in the face of continuing gene flow (e.g., Zancolli et al., 2019). As a result, the ability of antivenoms to neutralise different venoms can vary in unpredictable ways at all taxonomic levels (Williams et al., 2011). ...
Snakebite incidence at least partly depends on the biology of the snakes involved. However, studies of snake biology have been largely neglected in favour of anthropic factors, with the exception of taxonomy, which has been recognised for some decades to affect the design of antivenoms. Despite this, within-species venom variation and the unpredictability of the correlation with antivenom cross-reactivity has continued to be problematic. Meanwhile, other aspects of snake biology, including behaviour, spatial ecology and activity patterns, distribution, and population demography, which can contribute to snakebite mitigation and prevention, remain underfunded and understudied. Here, we review the literature relevant to these aspects of snakebite and illustrate how demographic, spatial, and behavioural studies can improve our understanding of why snakebites occur and provide evidence for prevention strategies. We identify the large gaps that remain to be filled and urge that, in the future, data and relevant metadata be shared openly via public data repositories so that studies can be properly replicated and data used in future meta-analyses.
... It was previously a species complex of Daboia russelii (synonym: Vipera russelii), comprising at least seven subspecies recognized by their geographical distributions as D. r. russelii (India), D. r. pulchella (Sri Lanka), D. r. nordicus (North India), D. r. siamensis (Indochina, southern China), D. r. formosensis (Taiwan), D. r. limitis and D. r. sublimitis (Indonesia) (Wüster, 1998). Recent taxonomy revision based on morphological and mitochondrial DNA data classified Russell's viper into two distinct clades (Thorpe et al., 2007): (1) Daboia russelii or the Western Russell's Viper that is found in the Indian subcontinent and neighboring countries in South Asia, including the island of Sri Lanka, and (2) Daboia siamensis or the Eastern Russell's Viper that is distributed east to the Bay of Bengal, covering areas in Myanmar, Thailand, Cambodia, China (Guangxi, Guangdong), Taiwan, and rather disjunctly, in Endeh, Flores, eastern Java, Komodo, Lombok Islands of Indonesia (Uetz et al., 2020). Both Western and Eastern Russell's Vipers are common causes of snakebite in the respective regions, contributing to significant global mortality and morbidity of snakebite envenomation (Adiwinata and Nelwan, 2015;Alirol et al., 2010;WHO, 2016). ...
Snakebite envenomation caused by the Western and Eastern Russell's Vipers (Daboia russelii and Daboia siamensis) may potentially induce capillary leak syndrome (CLS), while the use of antivenom in treating this has not been well examined. This study investigated the CLS-inducing toxicity of Russell's Viper venoms from various sources and examined the neutralization activity of regionally available antivenoms, using a newly devised mouse model. D. russelii venoms demonstrated a more consistent vascular leakage activity (76,000–86,000 CLS unit of vascular leak index, a function of the diameter and intensity of Evans Blue dye extravasation into dermis) than D. siamensis venoms (33,000–88,000 CLS unit). Both species venoms increased hematocrits markedly (53–67%), indicating hemoconcentration. Regional antivenoms (DsMAV-Thai, DsMAV-Taiwan, VPAV-India) preincubated with the venoms effectively neutralized the CLS effect to different extents. When the antivenoms were administered intravenously post-envenomation (challenge-rescue model), the neutralization was less effective, implying that CLS has a rapid onset that preceded the neutralizing activity of antivenom, and/or the antivenom has limited biodistribution to the venom's inoculation site. In conclusion, Russell's Viper venoms of both species from various locales induced CLS in mice. Antivenoms generally had limited efficacy in neutralizing the CLS effect. Innovative treatment for venom-induced CLS is needed.
... Cryptic diversity in the Oriental tropics has been well established across many taxa including plants (Clark et al., 2009;Okuyama & Kato, 2009), invertebrates (Huelsken et al., 2013;Adler et al., 2016;), vertebrates such as fishes (Matsumoto et al., 2010;Jaafar et al., 2012), amphibians (Stuart et al., 2006;McLeod, 2010;Nishikawa et al., 2012;Liu et al., 2018), reptiles Grismer et al., 2013;Guo et al., 2015;Luu et al., 2016;Klabacka et al., 2020), birds (Olsson et al., 2005;Outlaw & Voelker, 2008), and mammals (O'Brien et al., 2005;Thabah et al., 2006;Burton & Nietsch, 2010;Nater et al., 2017;Braulik et al., 2021). Within snakes, the elucidation of several 'well-known' taxa as species complexes, including Daboia russelii (Wüster et al., 1992;Thorpe et al., 2007), Naja naja (see Wüster, 1996), Ovophis monticola (Malhotra et al., 2011), Ahaetulla nasuta (Mallik et al., 2020), and Cerberus rynchops (Alfaro et al., 2004;Murphy et al., 2012) has demonstrated the need for such multi-criteria approaches. ...
... The refining of the species limits in the Ophiophagus complex provides a basis for the study of its venom variation, as shown in Russell's viper (Daboia Gray, 1842), which has similar biogeographic patterns (Thorpe et al., 2007). There is considerable evidence supporting a reduction in antivenom efficacy because of genetic and venom variation across distributions, especially where there is evidence of isolation (Wüster, 1996;Gutiérrez et al., 2006;Casewell et al., 2014;Tan et al.,2020;Senji Laxme et al., 2019;Senji Laxme et al., 2021a,b). ...
In widespread species, the diverse ecological conditions in which the populations occur, and the presence of many potential geographical barriers through their range are expected to have created ample opportunities for the evolution of distinct, often cryptic lineages. In this work, we tested for species boundaries in one such widespread species, the king cobra, Ophiophagus hannah (Cantor, 1836), a tropical elapid snake distributed across the Oriental realm. Based on extensive geographical sampling across most of the range of the species, we initially tested for candidate species (CS) using Maximum-Likelihood analysis of mitochondrial genes. We then tested the resulting CS using both morphological data and sequences of three single-copy nuclear genes. We used snapclust to determine the optimal number of clusters in the nuclear dataset, and Bayesian Phylogenetics and Phylogeography (BPP) to test for likely species status. We used non-metric multidimensional scaling (nMDS) analysis for discerning morphological separation. We recovered four independently evolving, geographically separated lineages that we consider Confirmed Candidate Species: 1) Western Ghats lineage; 2) Indo-Chinese lineage 3) Indo-Malayan lineage; 4) Luzon Island lineage, in the Philippine Archipelago. We discuss patterns of lineage divergence, particularly in the context of low morphological divergence, and the conservation implications of recognizing several endemic king cobra lineages.
... The hemotoxic activity is comparable to that reported for several other related Trimeresurus species, and presumably, the toxicity is mediated through convergently evolved hemotoxic toxins in the venoms of pit vipers (Tan et al., 2017;Tan et al., 2019;Lee et al., 2020;Liew et al., 2020;Yee et al., 2020). Variation in the snake venom composition, however, is common between and within species, irrespective of phylogenetic relatedness and biogeographical proximity (Thorpe et al., 2007;Mackessy, 2010a;Casewell et al., 2013;Sousa et al., 2013). The phenomenon has important clinical implications on the management of snakebite envenomation, as the toxic syndrome may vary due to different composition of toxins, and treatment with antivenom may not be effective because of variable antigenicity of the toxins in the venom (Lomonte et al., 2014;Kalita et al., 2018;Tan et al., 2018b;Hia et al., 2020;Tan et al., 2020a) Presently, antivenom remains the definitive treatment for snakebite envenomation. ...
Envenomation by two medically important Sundaic pit vipers, Trimeresurus wiroti (Malaysia) and Trimeresurus puniceus (Indonesia), causes hemotoxic syndrome with a potentially fatal outcome. Research on the compositions and antigenicity of these pit viper venoms is however lacking, limiting our understanding of the pathophysiology and treatment of envenomation. This study investigated the venom proteomes of both species through a protein decomplexation strategy, applying C18 reverse-phase high-performance liquid chromatography followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and protein identification through nano-electrospray ionization liquid chromatography-tandem mass spectrometry (nano-ESI-LCMS/MS) of trypsin-digested peptides. The venom antigenicity was profiled against the Thai Green Pit Viper Antivenom (GPVAV, a hetero-specific antivenom), using indirect enzyme-linked immunosorbent assay (ELISA). The venom proteomes of T. wiroti and T. puniceus consisted of 10 and 12 toxin families, respectively. The major proteins were of diverse snake venom serine proteases (19–30% of total venom proteins), snake venom metalloproteinases (17–26%), disintegrins.
(9–16%), phospholipases A2 (8–28%) and C-type lectins (~8%). These were putative snake toxins implicated in hemorrhage and coagulopathy, consistent with clinical hemotoxicity. GPVAV showed strong immunorecognition toward high and medium molecular weight proteins (e.g., SVMP and PLA2) in both venoms, while a lower binding activity was observed toward small proteins such as disintegrins. Conserved antigenicity in the major hemotoxins supported toxicity cross-neutralization by GPVAV and indicated that the immunorecognition of low molecular weight toxins may be optimized for improved binding efficacy. Taken together, the study provides insights into the pathophysiology and antivenom treatment of envenomation caused by T. wiroti and T. puniceus in the region.
