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A comprehensive investigation, incorporating both morphological and molecular analyses, has unveiled the existence of a hitherto unknown nematode species, Paracapillaria (Ophidiocapillaria) siamensis sp. nov., residing in the intestine of the monocled cobra, Naja kaouthia, in the central region of Thailand. This study integrates morphological characteristics, morphometric examination, scanning electron microscopy and molecular phylogenetic analysis (COI, 18S rRNA and ITS1 genes). The findings place the newly described species within the subgenus Ophidiocapillaria, elucidating its distinctive characteristics, including a frame-like proximal spicule shape, approximate lengths of 19 000 and 22 500 μm with approximate widths of 90 and 130 μm for males and females, 39‒45 stichocytes, elevated lips without protrusion, a dorsal bacillary band stripe with an irregular pattern of bacillary cells and evidence of intestinal infection. These features serve to differentiate it from other species within the same subgenus, notably Paracapillaria (Ophidiocapillaria) najae De, 1998, a species coexisting P. siamensis sp. nov. in the monocled cobra from the same locality. This study addresses the co-infection of the novel species and P. najae within the same snake host, marking the second documented instance of a paracapillariid species in the monocled cobra within the family Elapidae. The genetic characterization supports the formal recognition of P. siamensis sp. nov. as a distinct species, thereby underscoring its taxonomic differentiation within the Capillariidae family. This research identifies and characterizes the new nematode species, contributing valuable insights into the taxonomy of this nematode.

Antivenom is an essential treatment for snake envenomation; however, early adverse reactions (EARs) are major limitations to its use. We performed a retrospective cross-sectional study using Ramathibodi Poison Center data (January 2016 to December 2017) to clarify the incidence and severity of EARs following different F(ab’)2 antivenoms. Among 1006 envenomed patients, 684 (68%) received antivenom therapy with a total of 1157 doses, mostly green pit viper antivenom. The overall EAR incidence and rate were 22. 5% (154/684) and 15% (173/1157), respectively. The EAR rate following each type of antivenom was >10%, except for Russell’s viper antivenom (2.9%); the severe reaction rate was 2.6% (30/1157). Malayan pit viper bites caused a high incidence of EARs (37.8%) and the highest EAR rate (22.3%). Fifty-two cases developed anaphylaxis. All EARs occurred within 2 h after treatment initiation. No deaths were attributed to EARs. The duration of administration was significantly different between doses of antivenom that induced EARs and those that did not. In conclusion, all types and every dose of antivenom should be infused for 30–60 min. Preparation of resuscitation equipment and continuous clinical observation are crucial for at least 2 h after administration, and prompt treatment should be provided when EARs occur.

Understanding the burden of snakebite is crucial for developing evidence-informed strategies to pursue the goal set by the World Health Organization to halve morbidity and mortality of snakebite by 2030. However, there was no such information in the Association of Southeast Asian Nations (ASEAN) countries. A decision analytic model was developed to estimate annual burden of snakebite in seven countries, including Malaysia, Thailand, Indonesia, Philippines, Vietnam, Lao PDR, and Myanmar. Country-specific input parameters were sought from published literature, country's Ministry of Health, local data, and expert opinion. Economic burden was estimated from the societal perspective. Costs were expressed in 2019 US Dollars (USD). Disease burden was estimated as disability-adjusted life years (DALYs). Probabilistic sensitivity analysis was performed to estimate a 95% credible interval (CrI). We estimated that annually there were 242,648 snakebite victims (95%CrI 209,810-291,023) of which 15,909 (95%CrI 7,592-33,949) were dead and 954 (95%CrI 383-1,797) were amputated. We estimated that 161,835 snakebite victims (69% of victims who were indicated for antivenom treatment) were not treated with antivenom. Annual disease burden of snakebite was estimated at 391,979 DALYs (95%CrI 187,261-836,559 DALYs) with total costs of 2.5 billion USD (95%CrI 1.2-5.4 billion USD) that were equivalent to 0.09% (95%CrI 0.04-0.20%) of the region's gross domestic product. >95% of the estimated burdens were attributed to premature deaths. The estimated high burden of snakebite in ASEAN was demonstrated despite the availability of domestically produced antivenoms. Most burdens were attributed to premature deaths from snakebite envenoming which suggested that the remarkably high burden of snakebite could be averted. We emphasized the importance of funding research to perform a comprehensive data collection on epidemiological and economic burden of snakebite to eventually reveal the true burden of snakebite in ASEAN and inform development of strategies to tackle the problem of snakebite.

The parasitic nematode Paracapillaria (Ophidiocapillaria) najae De, 1998, found in the Indian cobra Naja naja is redescribed and re-illustrated in the present study. The monocled cobra Naja kaouthia was discovered to be a new host for this parasite in central Thailand. A comprehensive description extending the morphological and molecular characteristics of the parasites is provided to aid species recognition in future studies. The morphometric characters of 41 parasites collected from 5 cobra specimens are compared with those described in the original studies. Phylogenetic analyses using mitochondrial cytochrome c oxidase subunit 1 and nuclear 18S ribosomal RNA genes were performed to provide novel information on the systematics of P. najae. Similar characteristics were observed in the examined nematode samples, despite being found in different hosts, confirming their identity as P. najae. The molecular genetic results support the species status of P. najae, indicating P. najae is well defined and separated from other related nematode species in the family Capillariidae. Morphological descriptions, genetic sequences, evolutionary relationships among capillariids and new host and distribution records of P. najae are discussed. Paracapillaria najae specimens found in the Thai cobra had some morphological variation, and sexual size dimorphism was also indicated. Paracapillaria najae was found to infect various cobra host species and appeared to be common throughout the Oriental regions, consistent with its hosts' distribution.

Snakebite envenomation remains a significant global health concern, with antivenoms being the primary treatment. However, variations in venom composition can affect antivenom efficacy, leading to differences in immunoreactivity. This study aimed to evaluate and compare the immunological reactivity of venom components in Trimeresurus albolabris and Tropidolaemus wagleri venoms and further investigate the differences in antigenic properties of a key protein between two species that may influence antivenom recognition. The levels of immunological reactivity of monovalent (homospecific) antivenom and hemato polyvalent antivenom to Trimeresurus albolabris and Tropidolaemus wagleri venoms were evaluated using indirect ELISA. The immunoreactive levels of both antivenoms to antigenic proteins in Trimeresurus albolabris venom were comparable. In addition, both antivenoms reacted immunologically with antigens in Tropidolaemus wagleri venom. However, the hemato polyvalent antivenom showed greater reactivity to Tropidolaemus wagleri venom than the monovalent antivenom. The overall reactivity of the antivenoms to Trimeresurus albolabris venom was higher than that to Tropidolaemus wagleri venom. Using two-dimensional (2DE) immunoblotting and liquid chromatography mass-spectrometry-based proteomic technology (LC-MS/MS), immunoreactive and non-reactive proteins in both pit viper venoms were characterized and identified. Trimeresurus albolabris venom comprised a total of 235 spots, while Tropidolaemus wagleri venom contained 72 spots. Immunorecognition between the polyvalent antivenom and specific proteins in both venoms was mostly detected in proteins with a size over 30 kDa. Among the nine protein families identified in both venoms, the most frequently reactive proteins found in Trimeresurus albolabris venom were snake venom metalloproteinases (SVMP) and snake venom serine proteases (SVSP), while in Tropidolaemus wagleri venom, the most frequent were members of the L-amino acid oxidase (LAAO) family. For the non-immunoreactive proteins, we detected the highest identity numbers of phospholipase A 2 (PLA 2 ) in Trimeresurus albolabris venom and SVSP in Tropidolaemus wagleri venom. The distinctive characteristics between the non-reactive SVSP in Tropidolaemus wagleri venom and the reactive SVSP in Trimeresurus albolabris venom were investigated. The antigenic properties and predicted B cell epitopes were further analyzed using a computational approach. Structural and physicochemical analyses indicated that Loop 2 (residues 100–110) in the immunoreactive SVSP from Trimeresurus albolabris venom exhibited higher hydrophilicity and surface accessibility compared to the non-immunoreactive SVSP from Tropidolaemus wagleri venom. These findings provide important insights into the differences in antivenom reactivity to specific proteins across different snake venoms and may contribute to future research aimed at optimizing antivenom formulations.

The venomic profile of Asian mountain pit viper Ovophis monticola is clarified in the present study. Using mass spectrometry-based proteomics, 247 different proteins were identified in crude venom of O . monticola found in Thailand. The most abundant proteins were snake venom metalloproteases (SVMP) (36.8%), snake venom serine proteases (SVSP) (31.1%), and phospholipases A 2 (PLA 2 ) (12.1%). Less abundant proteins included L-amino acid oxidase (LAAO) (5.7%), venom nerve growth factor (3.6%), nucleic acid degrading enzymes (3.2%), C-type lectins (CTL) (1.6%), cysteine-rich secretory proteins (CRISP) (1.2%) and disintegrin (1.2%). The immunoreactivity of this viper’s venom to a monovalent antivenom against green pit viper Trimeresurus albolabris , or to a polyvalent antivenom against hemotoxic venom was investigated by indirect ELISA and two-dimensional (2D) immunoblotting. Polyvalent antivenom showed substantially greater reactivity levels than monovalent antivenom. A titer for the monovalent antivenom was over 1:1.28x10 7 dilution while that of polyvalent antivenom was 1:5.12x10 7 . Of a total of 89 spots comprising 173 proteins, 40 spots of predominantly SVMP, SVSP and PLA 2 were specific antigens for antivenoms. The 49 unrecognized spots containing 72 proteins were characterized as non-reactive proteins, and included certain types of CTLs and CRISPs. These neglected venom constituents could limit the effectiveness of antivenom-based therapy currently available for victims of pit viper envenomation.

Reptilian ferlavirus, a pathogen of serious concern in snakes, has been reported in Western countries, but little is known about its prevalence in Thailand, where many snake breeding farms are located. In this study, we investigated the reptilian ferlavirus via swab samples derived from 49 diseased snakes and 77 healthy snakes as well as tissue samples taken from nine dead snakes from five independent snake farms. Using molecular detection, we found the ferlavirus in 8.16% of diseased snakes, but not in healthy snakes. Out of nine farmed snakes, eight snakes derived from four farms were found to be positive. Four complete genome sequences of the ferlavirus were successfully obtained and phylogenetically clustered to the highly pathogenic ferlavirus. Tissue tropism of the ferlavirus was identified in various epithelial cell types using the in situ hybridization technique. Interestingly, the hybridization signals were strongly labeled in the male genital tract. Transmission electron microscopy was used to support the ferlaviral localization in the male genital tract. This study provides the first evidence of ferlavirus localization in the male genital tract and contributes to the knowledge about ferlavirus epidemiology, indicating that there needs to be further awareness and elucidation regarding vertical transmission of reptilian ferlavirus.

Malayan krait (Bungarus candidus) envenoming is a cause of significant morbidity and mortality in many Southeast Asian countries. If intubation and specific antivenom administration are delayed, the most significant life-threatening outcome may be the inhibition of neuromuscular transmission and subsequent respiratory failure. It is recommended that krait-envenomed victims without indications of neurotoxicity, e.g., skeletal muscle weakness or ptosis, immediately receive 10 vials of antivenom. However, the administration of excess antivenom may lead to hypersensitivity or serum sickness. Therefore, monitoring venom concentrations in patients could be used as an indicator for snake antivenom treatment. In this study, we aimed to develop a screen-printed gold electrode (SPGE) biosensor to detect B. candidus venom in experimentally envenomed rats. The gold electrodes were coated with monovalent Malayan krait IgG antivenom and used as venom detection biosensors. Electrochemical impedance spectrometry (EIS) and square wave voltammetry (SWV) measurements were performed to detect the electrical characterization between B. candidus venom and monovalent IgG antivenom in the biosensor. The EIS measurements showed increases in charge transfer resistance (Rct) following IgG immobilization and incubation with B. candidus venom solution (0.1–0.4 mg/mL); thus, the antibody was immobilized on the electrode surface and venom was successfully detected. The lowest current signal was detected by SWV measurement in rat plasma collected 30 min following B. candidus experimental envenoming, indicating the highest level of venom concentration in blood circulation (4.3 ± 0.7 µg/mL). The present study demonstrates the ability of the SPGE biosensor to detect B. candidus venom in plasma from experimentally envenomed rats. The technology obtained in this work may be developed as a detection tool for use along with the standard treatment of Malayan krait envenoming.

Background Understanding the burden of snakebite is crucial for developing evidence-informed strategies to pursue the goal set by the World Health Organization to halve morbidity and mortality of snakebite by 2030. However, there was no such information in the Association of Southeast Asian Nations (ASEAN) countries. Methodology A decision analytic model was developed to estimate annual burden of snakebite in seven countries, including Malaysia, Thailand, Indonesia, Philippines, Vietnam, Lao PDR, and Myanmar. Country-specific input parameters were sought from published literature, country’s Ministry of Health, local data, and expert opinion. Economic burden was estimated from the societal perspective. Costs were expressed in 2019 US Dollars (USD). Disease burden was estimated as disability-adjusted life years (DALYs). Probabilistic sensitivity analysis was performed to estimate a 95% credible interval (CrI). Principal findings We estimated that annually there were 242,648 snakebite victims (95%CrI 209,810–291,023) of which 15,909 (95%CrI 7,592–33,949) were dead and 954 (95%CrI 383–1,797) were amputated. We estimated that 161,835 snakebite victims (69% of victims who were indicated for antivenom treatment) were not treated with antivenom. Annual disease burden of snakebite was estimated at 391,979 DALYs (95%CrI 187,261–836,559 DALYs) with total costs of 2.5 billion USD (95%CrI 1.2–5.4 billion USD) that were equivalent to 0.09% (95%CrI 0.04–0.20%) of the region’s gross domestic product. >95% of the estimated burdens were attributed to premature deaths. Conclusion/Significance The estimated high burden of snakebite in ASEAN was demonstrated despite the availability of domestically produced antivenoms. Most burdens were attributed to premature deaths from snakebite envenoming which suggested that the remarkably high burden of snakebite could be averted. We emphasized the importance of funding research to perform a comprehensive data collection on epidemiological and economic burden of snakebite to eventually reveal the true burden of snakebite in ASEAN and inform development of strategies to tackle the problem of snakebite. Author summary In the Association of Southeast Asian Nations (ASEAN) countries, we estimated that annually there were 242,648 snakebite victims of which 15,909 victims were dead and 954 victims were amputated. We estimated that 69% of victims indicated for antivenom treatment were not treated with antivenom. Annual disease burden of snakebite was estimated at 391,979 disability-adjusted life years (DALYs) with estimated total costs of snakebite of 2.5 billion US Dollars which were equivalent to 0.09% of the region’s gross domestic product. Almost all of the estimated economic and disease burdens were related to deaths from snakebite envenoming which suggested that the remarkably high burden of snakebite could actually be averted. We emphasized the importance of funding research to perform a comprehensive data collection on epidemiological and economic burden of snakebite to eventually reveal the true burden of snakebite in ASEAN and inform development of strategies to tackle the problem of snakebite.

The two venomous pit vipers, Trimeresurus macrops and T. hageni, are distributed throughout Thailand, although their abundance varies among different areas. No species-specific antivenom is available for their bite victims, and the only recorded treatment method is a horse antivenom raised against T. albolabris crude venom. To facilitate assessment of the cross-reactivity of heterologous antivenoms, protein profiles of T. macrops and T. hageni venoms were explored using mass-spectrometry-based proteomics. The results show that 185 and 216 proteins were identified from T. macrops and T. hageni venoms, respectively. Two major protein components in T. macrops and T. hageni venoms were snake venom serine protease and metalloproteinase. The toxicity of the venoms on human monocytes and skin fibroblasts was analyzed, and both showed a greater cytotoxic effect on fibroblasts than monocytic cells, with toxicity occurring in a dose-dependent rather than a time-dependent manner. Exploring the protein composition of snake venom leads to a better understanding of the envenoming of prey. Moreover, knowledge of pit viper venomics facilitates the selection of the optimum heterologous antivenoms for treating bite victims.