Non-venomous Snakes Research Articles

Utility of Three Serum Biomarkers for Early Detection of Systemic Envenoming Following Viper Bites in Sri Lanka

BackgroundEarly detection of systemic envenoming is critical for early antivenom therapy to minimise morbidity and mortality from snakebite. We assessed the diagnostic utility of three serum biomarkers in the early detection of systemic envenoming in viper bites in rural Sri Lanka. MethodsAll confirmed snakebite patients admitted to Teaching Hospital Anuradhapura from July 2020 to June 2021 were included. On admission, blood was collected for venom concentrations, prothrombin time (PT)/international normalised ratio (INR), fibrinogen, serum creatinine (sCr), and three serum biomarkers - secretory phospholipase A2 (sPLA2), neutrophil gelatinase-associated lipocalin (sNGAL) and clusterin (sClu). Systemic envenoming was defined by the presence of venom-induced consumption coagulopathy, neurotoxicity, acute kidney injury or the presence of non-specific clinical effects. ResultsA total of 237 confirmed snakebite patients (Russell’s viper,72; Hump-nosed viper,80; non-venomous snakes,31; and unidentified bites,54) with sufficient pre-antivenom serum samples were recruited [median age: 42y (interquartile range: 29-53y); males: 173 (73%)]. Systemic envenoming occurred in 68 (94%) Russell’s viper bites, 48 (60%) hump-nosed viper bites and 45 (83%) unidentified bites. The median sPLA2 activity was 72nmol/ml/min (IQR: 30–164) for Russell’s viper envenoming, 12nmol/ml/min (IQR:9–16) for hump-nosed viper envenoming and 11nmol/ml/min (IQR:9-14) for non-venomous bites. There was no difference in sNGAL and sCLu between the three groups. The median sPLA2 activity of patients with systemic envenoming was 16nmol/min/mL (IQR:11–59nmol/min/mL) compared to 11 nmol/min/mL(IQR:9–14nmol/min/mL) in patients without systemic envenoming; difference between medians of 5nmol/min/mL (95% CI:4–12nmol/min/mL). The AUC-ROC of admission sPLA2 was the best predictor of systemic envenoming in all snakebites (AUC-ROC 0.72, 95% CI: 0.66 to 0.79), whereas sNGAL and sClu were poor predictors. sPLA2 was a better predictor of systemic envenoming in Russell’s viper bites (AUC-ROC 0.90, 95% CI:0.76-1.00) and in those presenting within 2h of bite. A sPLA2 activity >23.5nmol/min/ml had a sensitivity of 97% (95% CI:91-99.5%), but a low specificity of 41% (95% CI:34%-49%) in predicting systemic envenoming. A sPLA2 concentration of >46 nmol/min/ml on admission had a sensitivity of 100% (95% CI:51%-100%) and a specificity of 67% (95% CI:55%-77%) in predicting systemic envenoming in Russell’s viper bites. ConclusionsPLA2 is an early predictor of systemic envenoming following snakebite, particularly in Russell’s viper bites and in those who present early.

An efficient densenet-based deep learning model for Big-4 snake species classification

Snakebite poses a significant health threat in numerous tropical and subtropical nations, with around 5.4 million cases reported annually, which results in 1.8–2.7 million instances of envenomation, underscoring its critical impact on public health. The 'BIG FOUR' group comprises the primary committers responsible for most snake bites in India. Effective management of snakebite victims is essential for prognosis, emphasizing the need for preventive measures to limit snakebite-related deaths.The proposed initiative seeks to develop a transfer learning-based image classification algorithm using DenseNet to identify venomous and non-venomous snakes automatically. The study comprehensively evaluates the image classification results, employing accuracy, F1-score, Recall, and Precision metrics. DenseNet emerges as a potent tool for multiclass snake image classification, achieving a notable accuracy rate of 86%. The proposed algorithm intends to be incorporated into an AI-based snake-trapping device with artificial prey made with tungsten wire and vibration motors to mimic heat and vibration signatures, enhancing its appeal to snakes.The proposed algorithm in this research holds promise as a primary tool for preventing snake bites globally, offering a path toward automated snake capture without human intervention. These findings are significant in preventing snake bites and advancing snakebite mitigation strategies.

Genomic analysis reveals deep population divergence in the water snake Trimerodytes percarinatus (Serpentes, Natricidae).

Although several phylogeographic studies of Asian snakes have been conducted, most have focused on pitvipers, with non-venomous snakes, such as colubrids or natricids, remaining poorly studied. The Chinese keelback water snake (Trimerodytes percarinatus Boulenger) is a widespread, semiaquatic, non-venomous species occurring in China and southeastern Asia. Based on mitochondrial DNA (mtDNA) and single nucleotide polymorphism (SNP) data, we explored the population genetic structure, genetic diversity, and evolutionary history of this species. MtDNA-based phylogenetic analysis showed that T. percarinatus was composed of five highly supported and geographically structured lineages. SNP-based phylogenetic analysis, principal component analysis, and population structure analysis consistently revealed four distinct, geographically non-overlapping lineages, which was different from the mtDNA-based analysis in topology. Estimation of divergence dates and ancestral area of origin suggest that T. percarinatus originated ~12.68 million years ago (95% highest posterior density: 10.36-15.96 Mya) in a region covering southwestern China and Vietnam. Intraspecific divergence may have been triggered by the Qinghai-Xizang Plateau uplift. Population demographics and ecological niche modeling indicated that the effective population size fluctuated during 0.5 Mya and 0.002 Mya. Based on the data collected here, we also comment on the intraspecific taxonomy of T. percarinatus and question the validity of the subspecies T. p. suriki.

A study of clinical profile of snake bite at a tertiary care centre

Because India has long been a land of exotic snakes, snakebite is a serious occupational and rural hazard. Physicians pay very little attention to this occupational hazard despite the high morbidity and death. To study the various clinical profiles and the time interval between bite and start of treatment. Patients were categorized based on the envenomation centred by patient history and definitive bite evidence and graded (I-IV) grounded on a series of manifestations observed in association with the onset of treatment time that distinguishes a venomous from a non-venomous snake attack. Patients were obligating local inflammation owing to tourniquet use besides local innate therapies. Of the 100 patients deliberated, it was evident that there existed a minimal difference between the bites instigated by the snake type. Higher abnormal clotting was perceived on the arrival of patients (78%). While envenomation was predominantly reported to prompt primary coagulation abnormalities (84.32 %), neurotoxin manifestation was also found to occur at a lower rate (11.76 %). Both symptoms were also observed at a minimal level (3.92 %). Higher rates of renal failure were also reported and the clotting time normalization depended largely on patient admission time post-attack. In this investigation, the time gap between the bite and the commencement of therapy was not associated with the time required to normalize the coagulation abnormalities or develop a complication. The study also proposes appropriate protective and awareness measures that could save humankind and these reptiles together.

Parasites and microorganisms associated with the snakes collected for the "festa Dei serpari" in Cocullo, Italy.

While in much of the Western world snakes are feared, in the small, rural, mountainous town of Cocullo, in the middle of central Italy, snakes are annually collected and celebrated in a sacro-profane ritual. Every 1st of May, Serpari (snake catchers) capture and showcase dozens of non-venomous snakes to celebrate the ritual of San Domenico. In order to detect potential zoonotic pathogens within this unique epidemiological context, parasites and microorganisms of snakes harvested for the "festa dei serpari" ritual were investigated. Snakes (n = 112) were examined and ectoparasites collected, as well as blood and feces sampled. Ectoparasites were identified morpho-molecularly, and coprological examination conducted through direct smear and flotation. Molecular screenings were performed to identify parasites and microorganisms in collected samples (i.e., Mesostigmata mites, Anaplasma/Ehrlichia spp., Rickettsia spp., Borrelia burgdorferi sensu lato, Coxiella burnetii, Babesia/Theileria spp., Cryptosporidium spp., Giardia spp., Leishmania spp. and helminths). Overall, 28.5% (32/112) of snakes were molecularly positive for at least one parasite and/or microorganism. Endosymbiont Wolbachia bacteria were identified from Macronyssidae mites and zoonotic vector-borne pathogens (e.g., Rickettsia, Leishmania), as well as orally transmitted pathogens (i.e., Cryptosporidium, Giardia, Proteus vulgaris, Pseudomonas), were detected from blood and feces. Thus, given the central role of the snakes in the tradition of Cocullo, surveys of their parasitic fauna and associated zoonotic pathogens may aid to generate conservation policies to benefit the human-snake interactions, whilst preserving the cultural patrimony of this event.

Effect of Envenomation on Serum Hepatic Biomarkers in Snake (Echis Ocellatus) Bitten Individuals in Zamko Comprehensive Health Centre of the Jos University Teaching Hospital, North Central Nigeria.

Snake bite is a neglected public health issue in many tropical and subtropical countries of the world. About 5.4 million snakebites occur each year, resulting in 1.8 to 2.7 million cases of envenomation yearly. Hepatic markers have been reported to rise 3-6 hours after injection of venom in experimental animals. This study aims to biochemically assess ALT, AST and GGT levels as biomarkers of Echis ocellatus envenomation in victims of snake bite presenting at JUTH Comprehensive Health Centre Zamko 6hours post-bite and compare with values in those bitten by non-venomous snakes. The study was a comparative cross-sectional study where serum levels of AST, ALT and GGT were compared between the study group and the control group. Of the 150 respondents, 75 from each study group, 90(60.0%) were Male while 60(40.0%) were Female, with a Male to Female ratio of 1.5:1. The most predominant age group was 20-29 years 57(38.0%), the mean age was 39 years. The most predominant occupation was farming 82(54.7%). The majority 82(54.7%) had a secondary level of education. 91(60.7%) were married. A large majority of 123(82.0) had Christianity as their religion. We found a significant increase in the levels of AST (47.45IU/L) and GGT (61.62 IU/L) in the study group compared to AST (25.88IU/L), GGT (29.61IU/L) in the control group at p<0.05, while the level of ALT was similar in both groups at p>0.05. This implies that serum levels of AST and GGT can be used to diagnose envenomation in snakebite patients.

Role of Plastic Surgery in a Venomous Snake Bite: A Case Report

Snake bite is one of the major cause of accidental morbidity &amp; mortality worldwide. In riverine Bangladesh people of rural areas are mostly affected by snake bite. Majority of bites are caused by non-venomous snake and usually no casualty occurs but in case of venomous snake bite it can cause physical disability even death. Venom can cause local and systemic effect. Acute management is done by medical specialist but some patient develop surgical complication that need to be addressed by a plastic surgeon. A 43 years old male presented with a wound over dorsum of right hand and right middle finger with exposed MP joint (Metacarpophalangeal). He had history of snake bite 25 days back. Reconstruction done with flap and skin graft. Patient of venomous snake bite need a multidisciplinary team approach including plastic surgeon who take responsibility to restore both form and function.

Genome assembly and annotation of the king ratsnake, Elaphe carinata

The king ratsnake (Elaphe carinata) of the genus Elaphe is a common large, non-venomous snake widely distributed in Southeast and East Asia. It is an economically important farmed species. As a non-venomous snake, the king ratsnake predates venomous snakes, such as cobras and pit vipers. However, the immune and digestive mechanisms of the king ratsnake remain unclear. Despite their economic and research importance, we lack genomic resources that would benefit toxicology, phylogeography, and immunogenetics studies. Here, we used single-tube long fragment read sequencing to generate the first contiguous genome of a king ratsnake from Huangshan City, Anhui province, China. The genome size is 1.56 GB with a scaffold N50 of 6.53M. The total length of the genome is approximately 621 Mb, while the repeat content is 42.26%. Additionally, we predicted 22,339 protein-coding genes, including 22,065 with functional annotations. Our genome is a potentially useful addition to those available for snakes.

Unveiling the secrets of snakes: Analysis of environmental, socioeconomic, and spatial factors associated with snakebite risk in Paraná, Southern Brazil

The state of Paraná is home to three out of the five medically significant snake genera in Brazil and lacks of snakebite epidemiology studies. This study aimed to ascertain the spatial, environmental, and socioeconomic factors associated with snakebite risk by analyzing notification data of cases in the state of Paraná. Notification and socioeconomic data were gathered from the online platforms of the National System of Notifiable Diseases (SINAN) and the Brazilian Institute of Geography and Statistics (IBGE). Land cover and land use maps were obtained from the Mapbiomas platform in raster format and subsequently converted into vectors using QGis software. The proportions of land use and land cover in square kilometers (km2) were then calculated. All acquired data were tabulated using Microsoft Excel 365 software. For spatial analysis, GeoDa software version 1.20 was utilized to calculate the Global and Local Moran indices, assessing spatial correlations. Between 2007 and 2021, 12,877 notifications were recorded, with an average incidence of 8.22/100,000 inhabitants in the state, 8166 (63.41%) caused by Bothrops, 1534 (11.91%) caused by Crotalus, 56 (0.43%) caused by Micrurus. 1703 (13.22%) caused by non-venomous snake species, and the remaining cases did not have the identified causative species. The incidents caused by Bothrops and Crotalus showed different distribution patterns. Spatial analysis revealed that key factors contributing to snakebite risk included the presence of native forests, mangroves, apicuns, and monospecific planted forests. The population group at the highest risk comprised rural residents and workers. Furthermore, the absence of basic sanitation and proper garbage collection and disposal exhibited positive correlations with snakebites. Conversely, intensive farming practices with substantial mechanization and pastures demonstrated negative spatial correlations. This study has enabled the identification of the primary factors associated with snakebite risk, facilitating more targeted efforts to prevent snakebite accidents among vulnerable populations.

Ultrasonographic evaluation of the liver and gallbladder and hepatic histogram of non-venomous snakes.

This study aimed to describe sonographic features of the liver, gallbladder and hepatic histogram from grey-scale ultrasound in three species of healthy non-venomous snakes. Twenty-eight adult snakes were enrolled in the study, including 10 common boas (Boa constrictor), eight black-tailed pythons (Python molurus) and 10 rainbow boas (Epicrates crassus). The snakes fasted for 30 days and were manually restrained while conscious. For B. constrictor and P. molurus the liver and gallbladder were best visualized in ventral recumbency, and E. crassus in dorsal recumbency. A single elongated hepatic lobe was identified in all snakes. The gallbladder was positioned caudal and separated from the liver, with an oval shape and homogeneous anechoic content in the lumen, and thin and regular walls. A region of interest by pixel number was chosen for the liver, fat bodies, left kidney, and splenopancreas. The mean grey level (G) of the organs had significant differences within each species. Standard deviation of grey levels (SG ) had significant differences within B. constrictor and E. crassus. P. molurus had no significant difference among organs. The comparison among snakes showed that E. crassus had G of liver and splenopancreas lower than B. constrictor and P. molurus. The SG of the liver in E. crassus was lowest compared to B. constrictor and P. molurus. P. molurus showed the highest values in mean of G and SG . In conclusion, despite the liver and gallbladder having similar sonographic features, the grey-level histogram showed that liver echotexture and echogenicity differ among species.

Morganella sp. infection in scent gland of corn snake (Pantherophis guttatus) - case report

The corn snake (Pantherophis guttatus) is a non-venomous snake from the Colubridae family. The pair of scent glands is indispensable in the physiology of reproduction and defense of the species. This structure is located caudal to the cloaca. It is responsible for releasing a thick material based on lipids containing pheromones that perform functions associated with animal behavior and survival. This work aims to report infection by Morganella sp. in a scent gland in a female corn snake, evidencing the diagnosis and treatment. An increase in volume was seen in the final third, proximal to the cloaca, firm consistency, immobile, and approximately 4 cm long and painful to touch. Samples of the material were collected for bacterial culture and antibiogram examination, being positive for bacteria of the genus Morganella. Based on the result of the antibiogram, it was possible to determine the most appropriate therapeutic protocol, with the referral to perform the surgical procedure to remove the tissue compromised by the infection, remaining stable until the removal of the stitches 40 days after the procedure, with total surgical wound healing.

The anti-myotoxic effects and mechanisms of Sinonatrix annularis serum and a novel plasma metalloproteinase inhibitor towards Deinagkistrodon acutus envenomation

Non-venomous snakes commonly evolve natural resistance to venom to escape predators. Sinonatrix annularis serum has been shown to inhibit Deinagkistrodon acutus venom-induced hemorrhage and upregulation of serum CK, CK-MB, LDH, AST and ALT levels. Using TMT-labeled proteomics analysis, 168 proteins were found to be altered significantly in the envenomed gastrocnemius muscle and categorized into pathways such as complement and coagulation cascades, leukocyte transendothelial migration, and JAK/STAT signaling. These alterations were mitigated by S. annularis serum. Subsequently, a novel metalloproteinase inhibitor, SaMPI, was isolated from S. annularis serum by two-step chromatography. It showed strong antidotal effects against D. acutus envenomation, including inhibition of subcutaneous bleeding caused by crude venom and DaMP (a metalloproteinase derived from D. acutus) activity in a 1:1 ratio. Histology and immunoblotting analyses demonstrated that SaMPI mitigated myonecrosis, reduced neutrophil infiltration and local inflammatory factor release, and retarded JAK/STAT and MAPK signaling activation. Analysis of the SaMPI gene cloned by 5′-RACE revealed a shared sequence identity of 58–79% with other SVMP inhibitors. These findings demonstrate the protective effects of SaMPI and indicate its potential value as a candidate for viper bite adjuvant therapy.

The genome assembly and annotation of the Oriental rat snake Ptyas mucosa.

The Oriental rat snake Ptyas mucosa is a common non-venomous snake of the colubrid family, spanning most of South and Southeast Asia. P.mucosa is widely bred for its uses in traditional medicine, scientific research, and handicrafts. Therefore, genome resources of P.mucosa could play an important role in the efficacy of traditional medicine and the analysis of the living environment of this species. Here, we present a highly continuous P.mucosa genome with a size of 1.74Gb. Its scaffold N50 length is 9.57Mb, and the maximal scaffold length is 78.3Mb. Its CG content is 37.9%, and its gene integrity reaches 86.6%. Assembled using long-reads, the total length of the repeat sequences in the genome reaches 735Mb, and its repeat content is 42.19%. Finally, 24,869 functional genes were annotated in this genome. This study may assist in understanding P.mucosa and supporting medicinal research.

Clinical Profile and Pharmacological Management of Snakebites in Community Care Units: A Retrospective Study Using Two Military Hospital Databases in South Thailand.

Snakebite envenoming is an occupational hazard in remote rural areas of South Thailand, where the highest incidence of snakebites is reported. In this work, a hospital-based retrospective study of snakebite patients from 2012 to 2022 at Fort Wachirawut Hospital and Fort Thepsatrisrisunthon Hospital, located in Nakhon Si Thammarat province, Thailand was conducted. Data from the laboratory investigation, physical examinations of snakebite victims, and clinical management, including pharmacological and non-pharmacological treatments, were evaluated. A total of 54 snakebite victims were included. The median age of patients was 49 years (IQR, 28 to 63). Males accounted for 74.1% of all participants. The majority of patients were bitten by Malayan pit vipers (68.5%), followed by unidentified snakes (18.5%), other non-venomous snakes (7.4%), and cobras (5.6%). The most common clinical manifestations were swelling (90.2%) and local pain (73.2%). One patient experienced respiratory failure following an envenoming by an unidentified venomous snake. No deaths were observed in this study. In total, 24 patients received antivenom administration (44.4%), most of whom were from Fort Wachirawut Hospital. Patients who were administered antivenom showed a median admission duration of three days (IQR, 3 to 4), compared with two days (IQR, one to three) for those who did not receive antivenom treatment (p < 0.001). In addition, paracetamol and prophylactic antibiotics, namely, amoxicillin-clavulanate and dicloxacillin, were the most common pharmacotherapies following snakebites. Overall, it was observed that these two community hospitals undertook appropriate clinical management under the standard guidelines for snakebite patients. This might be due to the effective emergency management, facilities, and clinical consultations. Finally, the management process in the medical teams also plays a crucial role in minimizing the severity of snakebite outcomes.

Pattern and seasonal variations of snake bite in southern part of Bangladesh

Background: Snake bite is one of the leading causes of mortality and morbidity in many regions, notably the rural tropics, and is a globally overlooked occurrence. Present study is aimed to find the pattern and seasonal variations of snakebite in the southern part of Bangladesh.&#x0D; Methods: A one-year retrospective survey was done on 554 venomous or non-venomous snake bite patients admitting in a tertiary care hospital Chittagong Medical College Hospital, Bangladesh. Through the administration of a questionnaire, data on snake bites and kinds, date and time of bite and envenomation characteristics were obtained from respondents over a twelve-month period. After data collection, SPSS-20 was utilized for analysis.&#x0D; Results: In the present study male (64.1%) were found more affected than female and the vast majority of snake bite victims are younger Regarding pattern of envenomation, 400(72.2%) patients had no features of envenomation, 37(6.7%) local envenomation with spontaneous bleeding, 35(6.3%) had systemic envenomation, 74(13.4%) had local envenomation and 8(1.4%) had local swelling with neurotoxicity. Most of the patients were male (64.1%), female was mostly housewives (24.9%) and 68.1% were from poor socioeconomic status. Regarding monthly distribution of study patients where most patients were found during May to September and venomous bite were also more common during the month of May to August. Analysis of species of snakes revealed 89(16.1%) were pit viper, 87(15.7%) were dora snake, 23(4.2%) were cobra and 355(64.1%) snake bite were remained unidentified.&#x0D; Conclusions: During the monsoon season (May to September) in Bangladesh, the incidence of both nonvenomous and venomous snake bites is much high and poisonous snake bites are prevalent during this time. Poor access to health services and superstition regarding dealing with Ozahs are also a common finding in our study.&#x0D; Central Medical College Journal Vol 6 No 2 Jauly 2022 Page: 71-76

Health care workers' knowledge on identification, management and treatment of snakebite cases in rural Malawi: A descriptive study.

Snakebite envenoming remains a public health threat in many African countries, including Malawi. However, there is a shortage of literature on the knowledge of Health Care Workers (HCWs) and the prevalence of snakebite cases in Malawi. We interviewed HCWs in Neno District to assess their knowledge of snake identification and management of snakebites. We further reviewed patient registers from 2018 to 2021 in all 15 health facilities in the district. We used descriptive statistics to characterize the survey population, knowledge, snake antivenom (SAV) administration, and snake identification. Using "shapefiles" from Open Street Maps, we mapped villages with snakebite cases. Of the 105 HCWs interviewed, 58% were males, and 60% had worked for less than five years. The majority (n = 93, 89%) reported that snakebite envenoming was a problem in the district. Among the clinicians, 42% said they had prescribed SAV previously, while among nurses, only 26% had ever administered SAV. There were discrepancies among clinicians regarding the dosing of snake antivenom. Significant gaps in knowledge also existed regarding snake identification. While two-thirds of HCWs could correctly name and identify venomous snake species, most (> 90%) failed for non-venomous snakes. Most (n = 100, 95%) reported that snakebite victims visit traditional healers more than the hospital. Between 2018 and 2021, the Neno District registered 185 snakebites with a yearly average of 36 cases per 100,000 population. Fifty-two percent (n = 97) were treated as an inpatient; of these cases, 72% were discharged in less than three days, and two died. More snakebite cases were recorded in the eastern part of the district. Significant knowledge gaps exist among HCWs in Neno regarding prescription and administration of SAV and snake identification, which likely challenges the quality of services offered to snakebite victims.

Short-chain carboxylic acids in the scent gland secretions of the eastern small-scaled burrowing asp (Atractaspis fallax: Lamprophiidae, Serpentes, Reptilia)

Embedded in the tail base of all snakes is a pair of scent glands that open through ducts at the margin of the cloaca. Scent gland secretions (SGS), which typically are discharged when snakes are disturbed, are thought to deter predators. Previous chemical analyses have indicated carboxylic acids as the chief lipid constituents of SGS. We examined by GC-MS the SGS of the eastern small-scaled burrowing asp (Atractaspis fallax), a venomous, fossorial species in the Lamprophiidae, a diverse family containing more than 60 genera of mostly non-venomous African snakes. Our results confirm that acetic, propionic, 2-methylpropanoic, n-butanoic, and 3-methylbutanoic acids are the major constituents in the SGS samples of A. fallax. These compounds are widespread in the SGS of the Alethinophidia (‘typical snakes’). Some of these short-chain acids also occur in the anal glands of mammals and the uropygial (preen) glands of birds, where they arise via microbial activity. Whether these compounds in SGS have a similar origin is unknown.

The banded colour patterns of sea snakes discourage attack by predatory fishes, enabling Batesian mimicry by harmless species.

The evolution of bright 'warning' colours in nontoxic animals often is attributed to mimicry of toxic species, but empirical tests of that hypothesis must overcome the logistical challenge of quantifying differential rates of predation in nature. Populations of a harmless sea snake species (Emydocephalus annulatus) in New Caledonia exhibit colour polymorphism, with around 20% of individuals banded rather than melanic. Stability in that proportion over 20 years has been attributed to Batesian mimicry of deadly snake species by banded morphs of the harmless taxon. This hypothesis requires that banded colours reduce a snake's vulnerability to predation. We tested that idea by pulling flexible snake-shaped models through the water and recording responses by predatory fish. Black and banded lures attracted similar numbers of following fish, but attacks were directed almost exclusively to black lures. Our methods overcome several ambiguities associated with experimental studies on mimicry in terrestrial snakes and support the hypothesis that banded colour patterns reduce a non-venomous marine snake's vulnerability to predation.

Comparison of bedside clotting tests for detecting venom-induced consumption coagulopathy following Sri Lankan viper envenoming

Background The whole blood clotting test (WBCT) is commonly used for diagnosing venom-induced consumption coagulopathy (VICC) in resource-poor settings. We aimed to investigate the diagnostic accuracy of the WBCT and capillary blood clotting test (CBCT) for detecting VICC in viper envenoming in Sri Lanka. Methods All confirmed snakebites admitted to Teaching Hospital Anuradhapura from July 2020 to June 2021 were included. On admission, WBCTs after 15, 20 and 25 min observation times (WBCT-15, WBCT-20 and WBCT-25) and CBCT observed in 30 s intervals (CBCT-t), 5 and 10 min CBCT (CBCT-5 and CBCT-10) were done. Blood was collected simultaneously for prothrombin time (PT)/international normalized ratio (INR) and plasma fibrinogen. We defined VICC as an INR >1.5 (Incomplete VICC = INR>1.5 and complete VICC = ≥3.0). Results A total of 272 confirmed snakebites (Russell’s viper[76], hump-nosed viper[89], non-venomous snakes[51] and unidentified bites[56]) were recruited (median age: 42 y [interquartile range: 30- 53 y]; 189 males [69%]). On admission, 82 (30%) had incomplete VICC (INR >1.5 and <3) and 77 (28%) had complete VICC (INR ≥3). Sixteen (6%) developed clinically apparent bleeding. The WBCT-15 had the best sensitivity of 47% for detecting VICC and 68% for complete VICC. The sensitivities of the WBCT-20, WBCT-25, CBCT-5 and CBCT-10 was 30–35%. The sensitivities of all tests were better in detecting complete VICC, VICC in Russell’s viper bites and more than 2 h post-bite. The WBCT-15 test had a sensitivity of 76% for VICC in confirmed Russell’s viper bites. For detection of VICC, CBCT-t had an an excellent sensitivity of 97%, but a poor specificity of 35% for an optimal cut-off of >6.25 min. Conclusion WBCTs are poorly diagnostic for VICC in Russell’s viper and hump-nosed viper envenoming, missing up to two-thirds of patients for some tests. The WBCT-15 was the best test, improving for more severe VICC and greater than 2 h post-bite.

Hepatic inhibitors expression profiling of venom-challenged Sinonatrix annularis and antidotal activities

Snake venom is considered a “toxin arsenal”, and it often induces a series of clinical and pathophysiological symptoms in snakebite victims. Interestingly, toxin inhibitors are commonly found in the serum of snakes and their predators. Sinonatrix annularis is a type of non-venomous snake that was reported to contain an “inhibitor cocktail”, including phospholipase A2 inhibitors (PLIs), metalloproteinase inhibitors (SVMPIs), and small serum protein (SSP). However, the sequences and activities of these components remain obscure. In this study, we performed envenomation challenges on S. annularis using venoms from Deinagkistrodon acutus, Agkistrodon halys and Naja atra. In brief, the maximum injected amount of venom was 360 mg/kg for D. acutus, 72 mg/kg for A. halys, and 18 mg/kg for N. atra. The mRNA expression of the inhibitors PLIα, PLIβ, PLIγ, SVMPI, serpin A1, and SSP showed a dose-dependent effect on envenomation. Liver homogenate from S. annularis (LH) was prepared and used to evaluate its inhibitory effect on snake venoms. As a result, LH showed significant neutralization of venom PLA2, mitigated hemorrhage, venom-induced muscle damage, and system toxicity. In the presence of LH, envenomated mice exhibited attenuated inflammation, apoptosis, oxidative damage, and mitigated changes in serum biochemical markers caused by venom. The study reveals the secret of “natural immunity” in snakes, namely, the “antivenom”, which consists of an inhibitor proteome or cocktail.