Taiwan’s venomous snakebite: epidemiological, evolution and geographic differences

Protobothrops jerdonii (Jerdon's pit viper) and Protobothrops himalayanus (Himalayan lance-headed pit viper) bites: Clinical report on envenomings from North-East India, managed through remote consultation by a national-level Poison control center

Members of the genus Protobothrops are amongst the more than twenty-eight range-restricted Indian pit viper species. Their bites and envenomings are rarely documented from India. Pit viper envenomings can be challenging to treat in the Indian setting, since available antivenoms do not satisfactorily neutralize their venoms. Herein, we present the first Indian reports on bites and envenoming by Protobothrops jerdonii and Protobothrops himalayanus resulting in local effects, coagulopathy and acute kidney injury in the case of the former and possible mild, isolated coagulopathy in the case of the latter; and discuss management-related challenges in the context of absent specific antivenoms.

Proteomic characteristics of six snake venoms from the Viperidae and Elapidae families in China and their relation to local tissue necrosis

Patients envenomed by snakes from the Viperidae and Elapidae families in China often have varying degrees of local tissue necrosis. Due to the relative clinical characteristics of local tissue necrosis and ulceration following envenoming, this study has analyzed the proteome of six snake venoms from the Viperidae and Elapidae family, and the toxin profiles of each snake were compared and correlated with the clinical manifestations that follow cytotoxic envenoming. Deinagkistrodon acutus and Naja atra envenomation induce severe ulceration, which is absent in Bungarus multicinctus envenomation and mild in the other three vipers. It is interesting to note that the proportion of c-type lectins (CTL) (20.63%) in Deinagkistrodon acutus venom was relatively high, which differs from the venom of other vipers. In addition, three-fingered toxin (3FTx) (2.15%) is present in the venom of Deinagkistrodon acutus, but has not been detected in the remaining three vipers. Snake venom metalloprotease (SVMP) (34.4%-44.7%), phospholipase A2 (PLA2) (9.81%-40.83%), and snake venom serine protease (SVSP) (9.44%-16.2%) represent the most abundant families of toxin in Viperidae venom. The Elapidae venom proteome was mainly composed of neurotoxins and cytotoxins, including 3FTx (39.28%-60.08%) and PLA2 (8.24%-58.95%) toxins, however, the proportion of CRISPS (26.36%) in Naja atra venom was relatively higher compared to Bungarus multicinctus venom. Significant differences in SVMP, SVSP, and 3FTx expression levels exist between the Viperidae and the Elapidae family. The main toxins responsible for the development of tissue necrosis and ulcerations following Viperidae envenoming are hematotoxins (SVSMP, SVSP) and myotoxins (PLA2). Deinagkistrodon acutus venom contains high levels of CTL and traces of 3FTx, leading to more severe local necrosis. However, Naja atra venom can also cause severe local necrosis through the effects of myotoxin (3FTx, CRISP, PLA2). Bungarus multicinctus venom does not contain myotoxins, resulting in pure systemic neurological manifestations no obvious necrosis of local tissue in patients.

Nationwide and long-term epidemiological research of snakebite envenomation in Taiwan during 2002-2014 based on the use of snake antivenoms: A study utilizing National Health Insurance Database

INTRODUCTION

In Taiwan, six venomous snake species with medical importance have been found; however, long-term epidemiological data of snakebite envenomation (SBE) is lacking. This study aimed to explore the epidemiology of SBE based on the distribution and use of different antivenoms in different parts of Taiwan to facilitate the development of prevention strategies and resource allocation.

METHODS AND RESULTS

This retrospective study was conducted using the Taiwan National Health Insurance Research Database from 2002 to 2014. A total of 12,542 patients were treated with antivenoms. The directly standardized cumulative incidence was 3.6 cases per 100,000 individuals based on the 2000 World Standard Population. The incidence of SBEs peaked in the summer (35.9%). The relative risk (RR) of male patients versus female patients was 2.5 (p < 0.0001). The RRs of patients aged 18-64 and ≥65 years versus those aged <18 years were 6.0 (p < 0.0001) and 14.3 (p < 0.0001), respectively. Furthermore, the RR of eastern Taiwan versus northern Taiwan was 6.8 (p < 0.0001). The RR of agricultural workers versus laborers was 5.5 (p < 0.0001). Compared with patients envenomed by Trimeresurus stejnegeri stejnegeri or Protobothrops mucrosquamatus, those envenomed by Naja atra or Bungarus multicinctus multicinctus were more likely to occur in central (adjusted odds ratio [aOR] = 2.6, p < 0.0001) or southern (aOR = 3.2, p < 0.0001) Taiwan, but less frequently among agricultural workers (aOR = 0.6, p < 0.0001). The overall case-fatality rate was 0.11%.

CONCLUSIONS

Among Asian countries, Taiwan had low incidence and case-fatality rates of SBE. Risk factors included male gender, old age, summer season, being in eastern Taiwan, and being an agricultural worker. Differences of the epidemiological findings between snake species should be focused on when developing strategies for snakebite prevention.

Detection of cytotoxins by sandwich-ELISA for discrimination of cobra envenomation and indication of necrotic severity

Snake envenoming is both a healthcare and socioeconomic problem for developing countries and underserved communities. In Taiwan, clinical management of Naja atra envenomation is a major challenge, since cobra venom-induced symptoms are usually confused with hemorrhagic snakebites and current antivenom treatments do not effectively prevent venom-induced necrosis for which early surgical debridement should be administered. Identification and validation of biomarkers of cobra envenomation is critical for progress in setting a realistic goal for snakebite management in Taiwan. Previously, cytotoxin (CTX) was determined as one of potential biomarker candidates; however, its ability to discriminate cobra envenoming remains to be verified, especially in clinical practice. In this study, we selected a monoclonal single-chain variable fragment (scFv) and a polyclonal antibody to develop a sandwich enzyme-linked immunosorbent assay (ELISA) for CTX detection, which successfully recognized CTX from N. atra venom over that from other snake species. Using this specific assay, the CTX concentration in envenoming mice was shown to remain consistent in about 150 ng/mL during the 2-hour post-injection period. The measured concentration was highly correlated with the size of local necrosis in mouse dorsal skin, which the correlation coefficient is about 0.988. Furthermore, our ELISA method displayed 100 % of specificity and sensitivity in discriminating cobra envenoming among snakebite victims through CTX detection and the level of CTX in victim plasma was ranged from 5.8 to 253.9 ng/mL. Additionally, patients developed tissue necrosis at plasma CTX concentrations higher than 150 ng/mL. Thus, CTX not only serves as a verified biomarker for discrimination of cobra envenoming but also a potential indicator of severity of local necrosis. In this context, detection of CTX may facilitate reliable identification of envenoming species and improve snakebite management in Taiwan.

Wound Infection of Snakebite from Venomous Protobothrops mucrosquamatus, Viridovipera stejnegeri and Naja atra in Taiwan: Validation of BITE and Cobra BITE Scoring Systems and their Bacteriological Differences in Wound Cultures

Patients bitten by Protobothrops mucrosquamatus, Viridovipera stejnegeri, and Naja atra develop different degrees of wound infection. This study validated BITE and Cobra BITE scoring systems that we established previously. Bacteriological studies of patients with wound infection were conducted. The operating characteristic curves and area under the curve (AUC) and wound infection rates were compared between the derivation set (our previous study patient population) and the validation set (new patient cohorts enrolled between June 2017 and May 2021). No significant differences in the AUC for both the BITE (0.84 vs. 0.78, p = 0.27) and Cobra BITE (0.88 vs. 0.75, p = 0.21) scoring systems were observed between the derivation and validation sets. Morganella morganii and Enterococcus faecalis were the two most commonly detected bacteria in the microbiological study. More bacterial species were cultured from N. atra-infected wounds. Antibiotics such as amoxicillin with clavulanic acid, oxacillin, and ampicillin may not be suitable for treating patients with P. mucrosquamatus, V. stejnegeri, and N. atra bites in Taiwan. Carbapenem, third-generation cephalosporins, and fluoroquinolone may be superior alternatives.

Associated Clinical Factors for Coagulation Dysfunction due to Trimeresurus stejnegeri: A Retrospective Observational Study

Background

Trimeresurus stejnegeri (T.s) accounts for most snakebites in southern China, which always leads to coagulation dysfunction. Coagulopathy due to venom is widely considered to be a characteristic phenomenon of the DIC-like syndrome. It is vitally important for first-line clinicians to improve this condition as soon as possible. However, clinical factors associated with coagulation function in Trimeresurus stejnegeri has not been well characterized yet.

Materials

Patients bitten by vipers were admitted to the Emergency Department of a hospital in Shenzhen, southern China, from 2021 to 2022 and were retrospectively reviewed. Patient clinical characteristics and laboratory data were compared in the eligible patients bitten by T.s by their prothrombin time (PT), fibrinogen level (FIB), and platelet count on 2-3 days after bitten.

Results

105 patients were included in this study. The mean values of PT, FIB, and PLT are as follows: 12.8 ± 0.79 s, 2.25 ± 0.47 g/L, and 196.2 ± 57.1 × 10⁹/L. Uric acid (UA) (367.9 ± 103.85), blood glucose (6.53 + 1.64) show negative trend of correlation, while CRP (2.12 + 4.17) shows positive trend of association with coagulation function. The smoke and systolic blood pressure may exert negative effects on PT and PLT, respectively. Logistic regression analysis indicated that uric acid (UA) shows significant connection with PT (OR = 1.15 and P value <0.0001), FIB (OR = 0.89 and P value = 0.026), and PLT (OR = 0.79 and P value = 0.007). CRP is also shown to be associated with FIB (OR = 1.33 and P value = 0.043).

Conclusion

: Uric acid (UA) shows a significant association with PT, FIB, and PLT. CRP is related to FIB. Blood glucose shows a negative trend of correlation with PT. We do recommend physician should low the level of UA in some degree on the basis of injection of an antivenom serum.

Risk of stroke with antivenom usage after venomous snakebite in Taiwan: a population-based cohort study

BACKGROUND AND PURPOSE

Stroke is a rare complication of snakebites, but may lead to serious sequelae. We aimed to explore the relationship between venomous snakebite and the risk for acute stroke, in a nationwide population-based cohort study.

METHODS

This retrospective cohort study used claims data between 1 January 2000 and 31 December 2012, from the Taiwan National Health Insurance Research Database. The study included data of patients aged 18 years or older with venomous snakebite (n = 535), matched for propensity score with controls without venomous snakebite (n = 2140). The follow-up period was the duration from the initial diagnosis of venomous snakebite and administration of antivenom to the date of an acute stroke, or until 31 December 2013. The competing risk model was used to estimate the hazard ratio (HR) and 95% confidence intervals (CIs) of stroke, ischemic stroke and hemorrhagic stroke, after adjusting for demographic and other possible stroke risk factors.

RESULTS

The adjusted HR for the venomous snakebite group compared with the control group was 2.68 for hemorrhagic stroke (95% CI = 1.35-5.33). Stratified analysis showed that the older age group (>65 years old) had a higher risk of hemorrhagic stroke. A 2.72-fold significant increase in the risk for hemorrhagic stroke was observed following venomous snakebite with antivenom usage (95% CI = 1.41-5.26).

CONCLUSION

Venomous snakebite is associated with an increased risk of hemorrhagic stroke after the use of antivenom. Further study of the underlying mechanism is warranted.

Development of a Monoclonal scFv against Cytotoxin to Neutralize Cytolytic Activity Induced by Naja atra Venom on Myoblast C2C12 Cells

The Taiwanese cobra, Naja atra, is a clinically significant species of snake observed in the wild in Taiwan. Victims bitten by N. atra usually experience severe pain and local tissue necrosis. Although antivenom is available for treatment of cobra envenomation, its neutralization potency against cobra-induced necrosis is weak, with more than 60% of cobra envenoming patients developing tissue necrosis after antivenom administration. The present study found that cytotoxin (CTX) is a key component of N. atra venom responsible for cytotoxicity against myoblast cells. Anti-CTX IgY was generated in hens, and the spleens of these hens were used to construct libraries for the development of single chain variable fragments (scFv). Two anti-CTX scFv, S1 and 2S7, were selected using phage display technology and biopanning. Both polyclonal IgY and monoclonal scFv S1 reacted specifically with CTX in cobra venom. In a cell model assay, the CTX-induced cytolytic effect was inhibited only by monoclonal scFv S1, not by polyclonal IgY. Moreover, the neutralization potency of scFv S1 was about 3.8 mg/mg, approximately three times higher than that of conventional freeze-dried neurotoxic antivenom (FNAV). Collectively, these results suggest that scFv S1 can effectively neutralize CTX-induced cytotoxicity and, when combined with currently available antivenom, can improve the potency of the latter, thereby preventing tissue damage induced by cobra envenoming.

Effect of Agkistrodon halys antivenom in patients bit by green pit viper and the prognostic role of the disease - a retrospective cohort study

BACKGROUND AND AIMS

In Mainland China and Hong Kong, health authorities utilize Agkistrodon halys antivenom in the treatment of patients who sustained bites from green pit vipers. However, the treatment benefit of Agkistrodon halys antivenom among such patients is still controversial. The purpose of this study is to evaluate the coagulation parameters normalization time of Agkistrodon halys antivenom in patients who sustained green pit viper bites and explore independent risk factors of patient prognosis.

METHODS

Data were extracted from the Donghua Hospital Information System. Comparison of the two groups of patients - who used antivenom (GPUA) and who did not use antivenom (GPNUA) were performed using stratified analysis, univariate and multivariate ordered logistic regression models to evaluate the coagulation parameters normalization time. Univariate and multivariate ordered logistic regression models were used to explore independent risk factors of patient prognosis.

RESULTS

Between the GPUA and GPNUA groups, there is no significant difference in the coagulation parameters normalization time with the treatment of Agkistrodon halys antivenom. GPNUA consumed more cryoprecipitate and platelets and had a lower cost. The patient's severity of the bite, first coagulation profile, and dosages of fresh frozen plasma, platelet, and red cell suspension was found to be risk factors for the normalization time of coagulation parameters.

CONCLUSIONS

The therapeutic effect of Agkistrodon halys antivenom in green pit vipers bite patients is not quite satisfying. In addition, more attention should be paid to the first coagulation profile, blood clotting factors indices, platelet count (PLT), and hemoglobin when treating such patients.

Local Cytotoxic Effects in Cobra Envenoming: A Pilot Study

The cobra (genus Naja (N.)) is one of the most common venomous snakes. Due to its frequency and deadly complications of muscle paralysis, local necrosis, and chronic musculoskeletal disability, it should not be ignored. The pathology of devastating tissue destruction, even though specific antivenoms exist, is not fully clear. Here, we attempted to dig in envenomed tissues to study the clinical toxicology of cobra venom. Four cases of N. atra snake envenomation, in which the subjects developed advanced tissue injury, were involved in this study. We used enzyme-ligand sandwich immunoassay (ELISA) to assay the whole venom, cytotoxin A3 and short-chain neurotoxin (sNTX) in blood, bullae, wound discharge, and debrided tissue. We found that persistently high concentrations of venom and toxins, especially cytotoxin A3, were detected in bullae, wound discharge fluid and necrotic tissue of these patients even after large doses of specific antivenom treatment, and wide excision and advanced debridement could largely remove these toxins, lessen the size of necrosis, and promote wound healing. We also found that the point-of-care apparatus, ICT-Cobra kit, might be used to promptly monitor the wound condition and as one of the indicators of surgical intervention in cases of cobra envenomation in Taiwan.

Effectiveness of clotting factor replacement therapy after antivenom treatment on coagulopathic envenomation following green pit viper bites: a retrospective observational study

Background

Green pit vipers (GPVs), namely Trimeresurus albolabris and Trimeresurus stejnegeri accounts for most snakebites in Southern China. Green pit viper venom contains thrombin-like enzymes, resulting in defibrination syndrome. Using of clotting factor replacement after antivenom administration is controversial. The objective of this study was to investigate the effects of clotting factor replacement in coagulopathic patients with T. albolabris and T. stejnegeri bites after antivenom administration.

Methods

We retrospectively reviewed 123 patients who were bitten by T. albolabris and T. stejnegeri and were admitted to the Emergency Department of a hospital in Guangzhou, Southern China, from 2013 to 2019. Recovery of prothrombin time (PT) and fibrinogen level were compared among (1) fresh-frozen plasma (FFP) group; (2) cryoprecipitate (cryo) group; (3) FFP and cryo group; and (4) control group after antivenom administration.

Results

The incidence of coagulopathy was 31%. Persistent and late coagulopathy were the most common patterns among four groups. The median reduction in PT was 20.1 ± 31.2 s for FFP and cryo group. The median increase in fibrinogen level was very small: 0.05 ± 0.20 g/L for FFP group, 0.09 ± 0.37 g/L for cryo group and 0.07 ± 0.31 g/L for FFP and cryo group, respectively. The percentage of unimproved PT was markedly higher in the FFP and cryo group than the control group (P = 0.01 by log-rank test, P = 0.02 by Gehan-Breslow-Wilcoxon test). The percentage of unimproved fibrinogen level tended to be worse in the FFP and cryo group than the control group, but the different was marginal (P = 0.05 by Gehan-Breslow-Wilcoxon test, P = 0.07 by log-rank test). A total of 7.8% (7/90) of the patients in the clotting factor replacement groups developed anaphylaxis and heart failure.

Conclusion

There is no improvement in coagulopathy profile in patients with T. albolabris and T. stejnegeri bites who received clotting factor replacement after antivenom administration. But the results from GPVs may not be generalized to other species of venomous snakes.

Development of Antibody Detection ELISA Based on Immunoreactive Toxins and Toxin-Derived Peptides to Evaluate the Neutralization Potency of Equine Plasma against Naja atra in Taiwan

Naja atra, also known as Taiwanese cobra, is one of the most prevalent venomous snakes in Taiwan. Clinically, freeze-dried neurotoxic antivenom (FNAV) produced from horses by Taiwan Centers for Disease Control (CDC) has been the only approved treatment for N. atra envenoming for the last few decades. During antivenom production, large numbers of mice are used in the in vivo assay to determine whether the neutralization potency of hyperimmunized equines is satisfactory for large-scale harvesting. However, this in vivo assay is extremely laborious, expensive, and significantly impairs animal welfare. In the present study, we aimed to develop an in vitro ELISA-based system that could serve as an alternative assay to evaluate the neutralization potency of plasma from hyperimmunized equines. We initially obtained 51 plasma samples with known (high or low) neutralization potency assessed in vivo from 9 hyperimmunized equines and subsequently determined their antibody titers against the five major protein components of N. atra venom (neurotoxin (NTX), phospholipase A2 (PLA₂), cytotoxin (CTX), cysteine-rich secretory protein (CRISP), and snake venom metalloproteinase (SVMP)) via ELISA. The antibody titer against NTX was the most effective in discriminating between high and low potency plasma samples. To identify the specific epitope(s) of NTX recognized by neutralization potency-related antibodies, 17 consecutive NTX-derived pentadecapeptides were synthesized and used as antigens to probe the 51 equine plasma samples. Among the 17 peptides, immunoreactive signals for three consecutive peptides (NTX1-8, NTX1-9, and NTX1-10) were significantly higher in the high potency relative to low potency equine plasma groups (p < 0.0001). Our ELISA system based on NTX1-10 peptide (RWRDHRGYRTERGCG) encompassing residues 28–42 of NTX displayed optimal sensitivity (96.88%) and specificity (89.47%) for differentiating between high- and low-potency plasma samples (area under the receiver operating characteristic curve (AUC) = 0.95). The collective data clearly indicate that the antibody titer against NTX protein or derived peptides can be used to efficiently discriminate between high and low neutralization potency of plasma samples from venom-immunized horses. This newly developed antibody detection ELISA based on NTX or its peptide derivatives has good potential to complement or replace the in vivo rodent assay for determining whether the neutralization potency of equine plasma is satisfactory for large-scale harvesting in the antivenom production process against N. atra.

Coagulopathy After Viper Snakebite in Vietnam and Relationship with Time of Admission

Background

Snakebite envenoming is a potentially life-threatening condition and causes many serious consequences.

Subjects and Methods

Therefore, this study aimed to throw some light on coagulopathy after Viperidae envenomations at Vietnam Poison Control Center and the relationship between coagulopathy and time of admission. A prospective, descriptive study was conducted from October 2016 to April 2018. The survey questionnaire included socio-economic characteristics, characteristics of snakebite, signs and clinical symptoms and blood test. Disseminated intravascular coagulation (DIC) condition was diagnosed using the International Society on Thrombosis and Haemostasis (ISTH) criteria. Rotational thromboelastometry was evaluated using ROTEM^® delta system.

Results

A total of 41 cases of viper snakebite with the mean age of snakebite victims were 41.27 ± 14.72 years old. Mean hospital stay of the patients was 5.63± 3.29 days. The association between coagulation disorder and clotting time (CT) EXTEM prolonged, CT INTEM prolonged, CT FIBTEM prolonged remained significant (multivariable odds ratio MOR=5.81, 95% CI: 1.20–28.06; MOR= 9.32, 95% CI: 1.001–84.48; MOR=5.55, 95% CI: 1.12–27.50, respectively).

Conclusion

This study indicates a hypocoagulation status in ROTEM, elevated international normalised ratio (INR), activated partial thromboplastin time (APTT) and D-dimer, decreased fibrinogen concentration and platelet count following envenoming by Viperidae.

The role of a point-of-care ultrasound protocol in facilitating clinical decisions for snakebite envenomation in Taiwan: a pilot study

BACKGROUND

The incidence of acute compartment syndrome (ACS) following snakebite envenomation may be seriously overestimated in Taiwan. Snakebite-induced ACS is difficult to determine solely by clinical examination. Snakebite patients previously underwent surgical intervention based on speculation and general clinical examinations suggesting ACS presentations instead of direct intracompartmental pressure (IP) measurement prior to fasciotomy. Point-of-care ultrasound (POCUS) is a relatively widely available noninvasive tool. This study aimed to evaluate snakebite-envenomated patients for the presence of subcutaneous edema and diastolic retrograde arterial flow (DRAF).

MATERIALS AND METHODS

Snakebite patients were prospectively recruited between 2017 and 2019. All patients were examined with POCUS to locate edema and directly visualize and measure the arterial flow in the compressed artery. The presence of DRAF in the compressed artery is suggestive of ACS development because when compartment space restriction occurs, increased retrograde arterial flow is observed in the artery.

RESULTS

Twenty-seven snakebite patients were analyzed. Seventeen patients (63%) were bitten by Crotalinae snakes, seven (26%) by Colubridae, one (4%) by Elapidae, and two (7%) had unidentified snakebites. All Crotalinae bit patients received antivenom, had subcutaneous edema and lacked DRAF in a POCUS examination series.

DISCUSSION

POCUS facilitates clinical decisions for snakebite envenomation. We also highlighted that the anatomic site of the snakebite is an important factor affecting the prognosis of the wounds. There were limitations of this study, including a small number of patients and no comparison with the generally accepted invasive evaluation for ACS.

CONCLUSIONS

We are unable to state that POCUS is a valid surrogate measurement of ACS from this study but see this as a starting point to develop further research in this area. Further study will be needed to better define the utility of POCUS in patients envenomated by snakes throughout the world.

Snake venom proteome of Protobothrops mucrosquamatus in Taiwan: Delaying venom-induced lethality in a rodent model by inhibition of phospholipase A2 activity with varespladib

Protobothrops mucrosquamatus, also known as the brown spotted pit viper or Taiwanese habu, is a medically significant venomous snake in Taiwan, especially in the northern area. To more fully understand the proteome profile of P. mucrosquamatus, we characterized its venom composition using a bottom-up proteomic approach. Whole venom components were fractionated by RP-HPLC and then analyzed by SDS-PAGE. Each protein band in gels was excised and subjected to protein identification by LC-MS/MS. A subsequent proteomic analysis revealed the presence of 61 distinct proteins belonging to 19 families in P. mucrosquamatus venom. Snake venom metalloproteinase (SVMP; 29.4%), C-type lectin (CLEC; 21.1%), snake venom serine protease (SVSP; 17.6%) and phospholipase A₂ (PLA₂; 15.9%) were the most abundant protein families, whereas several low-abundance proteins, categorized into eight protein families, were demonstrated in P. mucrosquamatus venom for the first time. Because PLA₂ is known to make a major contribution to venom lethality, we evaluated whether the known PLA₂ inhibitor, varespladib, was capable of preventing the toxic effects of P. mucrosquamatus venom. This small-molecule drug demonstrated the ability to inhibit PLA₂ activity in vitro (IC₅₀ = 101.3 nM). It also blunted lethality in vivo, prolonging survival following venom injection in a mouse model, but it showed limited potency against venom-induced local hemorrhage in this model. Our findings provide essential biological and pathophysiological insights into the composition of P. mucrosquamatus venom and suggest PLA₂ inhibition as an adjunctive or alternative therapeutic strategy in the clinical management of P. mucrosquamatus envenoming in emergency medicine. SIGNIFICANCE: P. mucrosquamatus envenomation is a significant medical concern in Taiwan, especially in the northern region. Although antivenom is commonly used for rescuing P. mucrosquamatus envenoming, severe clinical events still occur, with more than 20% of cases requiring surgical intervention. Small-molecule therapy offers several advantages as a potential adjunctive, or even alternative, to antivenom treatment, such as heat stability, low antigenicity and ease of administration, among others. A deeper understanding of the venom proteome of P. mucrosquamatus would aid in the discovery of small-molecule drugs that could be repurposed to target specific venom proteins. Here, we applied a bottom-up proteomic approach to characterize the protein profile of P. mucrosquamatus venom. Varespladib, a small-molecule drug used to treat inflammatory disease, was repurposed to inhibit the toxicity of P. mucrosquamatus venom, and was shown to reduce the lethal effects of P. mucrosquamatus envenomation in a rodent model. Varespladib might be used as a first-aid therapeutic against P. mucrosquamatus envenoming in the pre-referral period and/or as an adjunctive agent administered together with anti-P. mucrosquamatus antivenom.

Benefits of Early In-Hospital Antivenom Administration to Patients with Protobothrops mucrosquamatus Envenomation

Protobothrops mucrosquamatus is one of the common venomous snakes in Southeast Asia. This retrospective cohort study conducted in six medical institutions in Taiwan aimed to obtain information on the optimal management strategies for P. mucrosquamatus snakebite envenomation. Data were extracted from the Chang Gung Research Database from January 2006 to December 2016. The association between early antivenom administration and patient demographics, pain requiring treatment with analgesic injections, and hospital length of stay was analyzed. A total of 195 patients were enrolled; 130 were administered antivenom within 1 hour after emergency department arrival (early group), whereas 65 were treated later than 1 hour after arrival (late group). No in-hospital mortality was identified. The difference in surgical intervention rates between the early and late groups was statistically insignificant (P = 0.417). Compared with the early group, the late group showed a higher rate of antivenom skin test performance (46.9% versus 63.1%, respectively, P = 0.033), longer hospital stay (42 ± 62 hours versus 99 ± 70 hours, respectively, P = 0.016), and higher rate of incidences of pain requiring treatment with analgesic injections (29.2% versus 46.2%, respectively, P = 0.019). After adjusting for confounding factors, early antivenom administration was associated with decreased pain requiring treatment with analgesic injections (adjusted odds ratio: 0.51, 95% CI: 0.260-0.985). Antivenom administration within 1 hour of arrival was associated with a decreased likelihood of experiencing pain and hospital length of stay in patients with P. mucrosquamatus snakebites. Antivenom skin testing was associated with delays in antivenom administration.

Risk factors associated with snake antivenom reaction and the role of skin test

Antivenom reactions are a common complication of snake antivenom. This study aimed to identify predicators of antivenom reaction and the involvement of antivenom skin test in antivenom reaction development. This retrospective cohort study was conducted in six medical institutions in Taiwan. Data were extracted from the Chang Gung Research Database (CGRD) from January 2006 to December 2016. The association between antivenom reaction and patient demographics, type and dose of antivenom, and skin test results was analyzed. The study enrolled 799 patients, including 219 who developed antivenom reactions. Compared to patients receiving both freeze-dried hemorrhagic (FH) and freeze-dried neurotoxic (FN) antivenom, those administered a single type had a lower antivenom reaction risk (adjusted odds ratios [aORs]: 0.5 and 0.4, 95% confidence interval [CI]: 0.35-0.74 and 0.24-0.69, FH and FN respectively). Patients administered a higher antivenom dose (≥ 5 vials) had higher antivenom reaction risk (aOR: 1.8, 95% CI: 1.23-2.76). A positive skin test result was also associated with antivenom reaction (aOR: 16.7, 95% CI: 5.42-51.22). The skin test showed high specificity (98.5%, 95% CI: 97.49%-99.83%) but low sensitivity (17.5%, 95% CI: 10.74%-24.18%). The antivenom skin test should be abolished because of the extremely low sensitivity and possible misinterpretation of results because of the limitation of this examination.

Effect of Traditional Chinese Medicine on Long-Term Outcomes of Snakebite in Taiwan

Herein, we review the characteristics of the six predominant venomous snakes in Taiwan and the effects of traditional Chinese medicine on the long-term outcomes of snakebite venom. We electronically searched databases, including PubMed, ClinicalKey, China National Knowledge Infrastructure, National Digital Library of Theses and Dissertations in Taiwan, and Airiti Library, from their inception to November 2019 by using the following Medical Subject Headings' keywords: snakebite, long-term, chronic, Chinese medicine, CAM, herb, and Taiwan. The most common long-term effects of snakebite envenomation include "migraine-like syndrome", brain injuries caused by hypoxia or intracranial hemorrhage, and chronic kidney disease. In addition, hypopituitarism is also worth mentioning. Traditional Chinese medicine can potentially be used in a complementary or alternative treatment for these effects, but additional studies are needed.

Pathogenesis of local necrosis induced by Naja atra venom: Assessment of the neutralization ability of Taiwanese freeze-dried neurotoxic antivenom in animal models

Naja atra envenomation is one of the most significant clinical snakebite concerns in Taiwan. Taiwanese freeze-dried neurotoxic antivenom (FNAV) is currently used clinically for the treatment of cobra snakebite, and has been shown to limit the mortality of cobra envenomation to less than 1%. However, more than half of victims (60%) require surgery because of local tissue necrosis, a major problem in patients with cobra envenomation. Although the importance of evaluating the neutralizing effect of FNAV on this pathology is recognized, whether FNAV is able to prevent the local necrosis extension induced by N. atra venom has not been investigated in detail. Cytotoxins (CTXs) are considered as the major components of N. atra venom that cause necrosis. In the current study, we isolated CTXs from whole cobra venom and used both whole venom and purified CTXs to develop animal models for assessing the neutralization potential of FNAV against venom necrotizing activity. Local necrotic lesions were successfully produced in mice using CTXs in place of whole N. atra venom. FNAV was able to rescue mice from a subcutaneously injected lethal dose of cobra venom; however, it was unable to prevent CTX-induced dermo-necrosis. Furthermore, using the minimal necrosis dose (MND) of CTXs and venom proteome data, we found a dose of whole N. atra venom suitable for FNAV and developed a workable protocol for inducing local necrosis in rodent models that successfully imitated the clinical circumstance of cobra envenoming. This information provides a more comprehensive understanding of the pathophysiology of N. atra envenomation, and serves as a guide for improving current antivenom strategies and advancing clinical snakebite management in Taiwan.

Naja atra envenomation is an important public health issue in Taiwan. Although the mortality rate of cobra snakebite is controlled using antivenom, more than half of victims develop symptoms of local necrosis and require surgical intervention. Whether the Taiwanese freeze-dried neurotoxic antivenom (FNAV) currently in clinical use is able to prevent the local necrosis extension induced by N. atra venom is still unclear. In this study, we developed a dermo-necrosis animal model using purified cytotoxins (CTXs), the major necrosis-related proteins from N. atra venom. We found that FNAV was able to neutralize the lethality of whole cobra venom, but was unable to neutralize the necrosis induced by CTXs in vivo. This finding introduced an example that supplementary quality control assays may be necessary to determine the effectiveness of antivenoms in neutralizing specific pathology induced by the venom; only evaluating the rodent lethality prevention is insufficient. Our results provide insights that should help improve current antivenoms and advance cobra snakebite management in Taiwan.

Venomics and Cellular Toxicity of Thai Pit Vipers (Trimeresurus macrops and T. hageni)

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.

Snake venom proteome and immuno-profiling of the hundred-pace viper, Deinagkistrodon acutus, in Taiwan

Deinagkistrodon acutus, also known as the hundred-pace viper or Chinese moccasin, is a clinically significant venomous snake in Taiwan. To address the lack of knowledge on the venom proteome of D. acutus, the venom composition was studied by a bottom-up proteomic approach combining reverse phase high-performance liquid chromatography, SDS-PAGE, and LC-MS/MS analysis. The immunoreactivity and cross-reactivity of Taiwanese freeze-dried D. acutus antivenom (DA-AV) and hemorrhagic antivenom (FH-AV) were investigated, as well. The proteomic analysis revealed the presence of 29 distinct proteins from D. acutus venom belonging to 8 snake venom protein families. Snake venom metalloproteinase (SVMP, 46.86%), C-type lectin (CLEC, 37.59%), phospholipase A₂ (PLA₂, 7.33%) and snake venom serine protease (SVSP, 6.62%) were the most abundant proteins. In addition to DA-AV, FH-AV also showed a profile of broad immunorecognition toward the venom of D. acutus. Remarkably, both antivenoms specifically reacted with the HPLC fractions containing SVMPs, and the titer was 5-10 times higher than fractions of other components. This information helps us to deeply understand the pathophysiology of D. acutus envenomation and guide us to development of more effective antivenom for clinical treatment.

Clinical and laboratory features distinguishing between Deinagkistrodon acutus and Daboia siamensis envenomation

Background

There are 6 species of venomous snakes in Taiwan. Two of them, Deinagkistrodon acutus (D. acutus) and Daboia siamensis (D. siamensis), can cause significant coagulopathy. However, a significant proportion of patients with snakebites cannot identify the correct snake species after envenomation, which hampers the application of antivenom. Hence, the differential diagnosis between the two snakebites by clinical presentations is important. This study aims to compare their clinical and laboratory features for the purpose of differential diagnosis between the two snakebites.

Methods

We retrospectively reviewed the medical records of patients who arrived at the emergency department due to D. acutus or D. siamensis envenomation, between 2003 and 2016, in one medical center in eastern Taiwan. Since these snakebites are rare, we also included 3 cases reported from another hospital in central Taiwan.

Results

In total, 15 patients bitten by D. acutus and 12 patients by D. siamensis were analyzed. Hemorrhagic bulla formation and the need for surgical intervention only presented for D. acutus envenomation cases (Both 53.3% vs. 0.0%, P = 0.003). As to laboratory features, lower platelet counts (20.0 ×  10³/μL [interquartile range, 14–66 × 10³/μL] vs. 149.0 × 10³/μL [102.3–274.3 × 10³/μL], P = 0.001), lower D-dimer level (1423.4 μg/L [713.4–4212.3 μg/L] vs. 12,500.0 μg/L [2351.4–200,000 μg/L], P = 0.008), higher proportion of patients with moderate-to-severe thrombocytopenia (platelet count < 100 × 10³/μL) (80% vs. 16.7%, odds ratio (OR) = 20.0, 95% CI, 2.77–144.31; P = 0.002), and lower proportion of patients with extremely high D-dimer (> 5000 ng/mL) (16.7% vs. 66.7%, adjusted OR = 0.1 (95% CI, 0.01–0.69; P = 0.036) were found among cases of D. acutus envenomation compared to D. siamensis envenomation. The combination of hemorrhagic bulla, thrombocytopenia, and a lack of extremely high D-dimer had good discriminatory power (area under the curve (AUC) = 0.965; 95% CI, 0.904–1.00) for distinguishing D. acutus from D. siamensis envenomation.

Conclusions

The presentation of moderate to severe thrombocytopenia (platelet count < 100 × 10³/μL) and hemorrhagic bulla formation may indicate D. acutus envenomation. However, the envenomed patient with extremely high D-dimer levels may indicate a D. siamensis envenomation. These findings may help diagnose and select the right antivenom in patients with unknown snakebites who present significant coagulopathy.

Development of sandwich ELISA and lateral flow strip assays for diagnosing clinically significant snakebite in Taiwan

Taiwan is an island located in the south Pacific, a subtropical region that is home to 61 species of snakes. Of these snakes, four species—Trimeresurus stejnegeri, Protobothrops mucrosquamatus, Bungarus multicinctus and Naja atra—account for more than 90% of clinical envenomation cases. Currently, there are two types of bivalent antivenom: hemorrhagic antivenom against the venom of T. stejnegeri and P. mucrosquamatus, and neurotoxic antivenom for treatment of envenomation by B. multicinctus and N. atra. However, no suitable detection kits are available to precisely guide physicians in the use of antivenoms. Here, we sought to develop diagnostic assays for improving the clinical management of snakebite in Taiwan. A two-step affinity purification procedure was used to generate neurotoxic species-specific antibodies (NSS-Abs) and hemorrhagic species-specific antibodies (HSS-Abs) from antivenoms. These two SSAbs were then used to develop a sandwich ELISA (enzyme-linked immunosorbent assay) and a lateral flow assay comprising two test lines. The resulting ELISAs and lateral flow strip assays could successfully discriminate between neurotoxic and hemorrhagic venoms. The limits of quantification (LOQ) of the ELISA for neurotoxic venoms and hemorrhagic venoms were determined to be 0.39 and 0.78 ng/ml, respectively, and the lateral flow strips were capable of detecting neurotoxic and hemorrhagic venoms at concentrations lower than 5 and 50 ng/ml, respectively, in 10–15 min. Tests of lateral flow strips in 21 clinical snakebite cases showed 100% specificity and 100% sensitivity for neurotoxic envenomation, whereas the sensitivity for detecting hemorrhagic envenomation samples was 36.4%. We herein presented a feasible strategy for developing a sensitive sandwich ELISA and lateral flow strip assay for detecting and differentiating venom proteins from hemorrhagic and neurotoxic snakes. A useful snakebite diagnostic guideline according to the lateral flow strip results and clinical symptoms was proposed to help physicians to use antivenoms appropriately. The two-test-line lateral flow strip assay could potentially be applied in an emergency room setting to help physicians diagnose and manage snakebite victims.

Snakebite is a public health issue that causes life-threatening medical emergencies. Rapid diagnosis of snakebite in the clinic is a critical necessity in many tropical and subtropical countries, where various venomous snakes are common. Venoms from different snake species contain distinct protein components that require treatment with different antivenoms. However, given the similarity in clinical symptoms among some snake envenomations, it is often challenging for physicians to precisely define the snake species responsible for envenomation. Thus, a reliable method or assay for rapidly diagnosing envenoming species is urgently needed. Here, we present a two-step affinity purification procedure for generating species-specific antibodies (SSAbs) from antivenom, followed by the development of a sandwich ELISA (enzyme-linked immunosorbent assay) and lateral flow strip assay using these SSAbs. This feasible and cost-effective strategy allowed us to develop workable assays for distinguishing between venom proteins from hemorrhagic and neurotoxic snakes in Taiwan. The usefulness of this strategy was demonstrated in the clinic, where both diagnostic assays were shown capable of detecting venoms in blood samples from snakebite patients. Together with the observation of clinical symptoms, the two-test-line lateral flow strip assay is potentially applicable in an emergency room setting to improve snakebite diagnosis and management.

Protobothrops mucrosquamatus Bites to the Head: Clinical Spectrum from Case Series

Protobothrops mucrosquamatus (Trimeresurus mucrosquamatus) is a medically important species of pit viper with a wide geographic distribution in Southeast Asia. Bites by P. mucrosquamatus mostly involve the extremities. Little is known about the toxic effects of P. mucrosquamatus envenoming to the head because of the infrequency of such occurrence. To better delineate the clinical manifestations of envenoming to the head, we report three patients who suffered from P. mucrosquamatus bites to the head and were treated successfully. All three patients developed progressive soft tissue swelling extending from head to neck, with two patients expanding further onto the anterior chest wall. Mild thrombocytopenia was noted in two patients. One patient had transient acute renal impairment and airway obstruction, necessitating emergent intubation. All three patients received high doses of species-specific antivenom with recovery within 1 week. No adverse reactions to antivenom were observed.

Vulnerability to snakebite envenoming: a global mapping of hotspots

BACKGROUND

Snakebite envenoming is a frequently overlooked cause of mortality and morbidity. Data for snake ecology and existing snakebite interventions are scarce, limiting accurate burden estimation initiatives. Low global awareness stunts new interventions, adequate health resources, and available health care. Therefore, we aimed to synthesise currently available data to identify the most vulnerable populations at risk of snakebite, and where additional data to manage this global problem are needed.

METHODS

We assembled a list of snake species using WHO guidelines. Where relevant, we obtained expert opinion range (EOR) maps from WHO or the Clinical Toxinology Resources. We also obtained occurrence data for each snake species from a variety of websites, such as VertNet and iNaturalist, using the spocc R package (version 0.7.0). We removed duplicate occurrence data and categorised snakes into three groups: group A (no available EOR map or species occurrence records), group B (EOR map but <5 species occurrence records), and group C (EOR map and ≥5 species occurrence records). For group C species, we did a multivariate environmental similarity analysis using the 2008 WHO EOR maps and newly available evidence. Using these data and the EOR maps, we produced contemporary range maps for medically important venomous snake species at a 5 × 5 km resolution. We subsequently triangulated these data with three health system metrics (antivenom availability, accessibility to urban centres, and the Healthcare Access and Quality [HAQ] Index) to identify the populations most vulnerable to snakebite morbidity and mortality.

FINDINGS

We provide a map showing the ranges of 278 snake species globally. Although about 6·85 billion people worldwide live within range of areas inhabited by snakes, about 146·70 million live within remote areas lacking quality health-care provisioning. Comparing opposite ends of the HAQ Index, 272·91 million individuals (65·25%) of the population within the lowest decile are at risk of exposure to any snake for which no effective therapy exists compared with 519·46 million individuals (27·79%) within the highest HAQ Index decile, showing a disproportionate coverage in reported antivenom availability. Antivenoms were available for 119 (43%) of 278 snake species evaluated by WHO, while globally 750·19 million (10·95%) of those living within snake ranges live more than 1 h from population centres. In total, we identify about 92·66 million people living within these vulnerable geographies, including many sub-Saharan countries, Indonesia, and other parts of southeast Asia.

INTERPRETATION

Identifying exact populations vulnerable to the most severe outcomes of snakebite envenoming at a subnational level is important for prioritising new data collection and collation, reinforcing envenoming treatment, existing health-care systems, and deploying currently available and future interventions. These maps can guide future research efforts on snakebite envenoming from both ecological and public health perspectives and better target future estimates of the burden of this neglected tropical disease.

FUNDING

Bill & Melinda Gates Foundation.

Comprehensive Snake Venomics of the Okinawa Habu Pit Viper, Protobothrops flavoviridis, by Complementary Mass Spectrometry-Guided Approaches

The Asian world is home to a multitude of venomous and dangerous snakes, which are used to induce various medical effects in the preparation of traditional snake tinctures and alcoholics, like the Japanese snake wine, named Habushu. The aim of this work was to perform the first quantitative proteomic analysis of the Protobothrops flavoviridis pit viper venom. Accordingly, the venom was analyzed by complimentary bottom-up and top-down mass spectrometry techniques. The mass spectrometry-based snake venomics approach revealed that more than half of the venom is composed of different phospholipases A2 (PLA₂). The combination of this approach and an intact mass profiling led to the identification of the three main Habu PLA₂s. Furthermore, nearly one-third of the total venom consists of snake venom metalloproteinases and disintegrins, and several minor represented toxin families were detected: C-type lectin-like proteins (CTL), cysteine-rich secretory proteins (CRISP), snake venom serine proteases (svSP), l-amino acid oxidases (LAAO), phosphodiesterase (PDE) and 5'-nucleotidase. Finally, the venom of P. flavoviridis contains certain bradykinin-potentiating peptides and related peptides, like the svMP inhibitors, pEKW, pEQW, pEEW and pENW. In preliminary MTT cytotoxicity assays, the highest cancerous-cytotoxicity of crude venom was measured against human neuroblastoma SH-SY5Y cells and shows disintegrin-like effects in some fractions.

Translational Venomics: Third-Generation Antivenomics of Anti-Siamese Russell's Viper, Daboia siamensis, Antivenom Manufactured in Taiwan CDC's Vaccine Center

The venom proteome of Siamese Russell’s viper from Taiwan, alongside complementary in vivo lethality neutralization assay and in vitro third-generation antivenomics assessment of the preclinical efficacy of the homologous antivenom manufactured in Taiwan CDC’s Vaccine Center, are here reported. Taiwanese Russell’s viper venom proteome comprised 25 distinct gene products, with the heterodimeric PLA₂ viperotoxin-F representing the most abundant toxin (47.5% of total venom proteome). Coagulation FV-activating serine proteinase (RVV-V, 14%), the PIV-SVMP activator of FX (RVV-FX, 8.5%), and less abundant toxins from nine protein families, make up its venom proteome. Venom composition-pathology correlations of D. siamensis envenomings in Taiwan are discussed. The lethal effect of Taiwanese D. siamensis venom was 0.47 mg/g mouse. Antivenomics-guided assessment of the toxin recognition landscape of the Taiwanese Russell’s viper antivenom, in conjunction with complementary in vivo neutralization analysis, informed the antivenom’s maximal toxin immunorecognition ability (14 mg total venom proteins/vial), neutralization capacity (6.5 mg venom/vial), and relative content of lethality neutralizing antibodies (46.5% of the toxin-binding F(ab’)₂ antibodies). The antivenomics analysis also revealed suboptimal aspects of the CDC-Taiwan antivenom. Strategies to improve them are suggested.

Analysis of the efficacy of Taiwanese freeze-dried neurotoxic antivenom against Naja kaouthia, Naja siamensis and Ophiophagus hannah through proteomics and animal model approaches

In Southeast Asia, envenoming resulting from cobra snakebites is an important public health issue in many regions, and antivenom therapy is the standard treatment for the snakebite. Because these cobras share a close evolutionary history, the amino acid sequences of major venom components in different snakes are very similar. Therefore, either monovalent or polyvalent antivenoms may offer paraspecific protection against envenomation of humans by several different snakes. In Taiwan, a bivalent antivenom—freeze-dried neurotoxic antivenom (FNAV)—against Bungarus multicinctus and Naja atra is available. However, whether this antivenom is also capable of neutralizing the venom of other species of snakes is not known. Here, to expand the clinical application of Taiwanese FNAV, we used an animal model to evaluate the neutralizing ability of FNAV against the venoms of three common snakes in Southeast Asia, including two ‘true’ cobras Naja kaouthia (Thailand) and Naja siamensis (Thailand), and the king cobra Ophiophagus hannah (Indonesia). We further applied mass spectrometry (MS)-based proteomic techniques to characterize venom proteomes and identify FNAV-recognizable antigens in the venoms of these Asian snakes. Neutralization assays in a mouse model showed that FNAV effectively neutralized the lethality of N. kaouthia and N. siamensis venoms, but not O. hannah venom. MS-based venom protein identification results further revealed that FNAV strongly recognized three-finger toxin and phospholipase A2, the major protein components of N. kaouthia and N. siamensis venoms. The characterization of venom proteomes and identification of FNAV-recognizable venom antigens may help researchers to further develop more effective antivenom designed to block the toxicity of dominant toxic proteins, with the ultimate goal of achieving broadly therapeutic effects against these cobra snakebites.

Cobra envenomation is a public health issue in Southeast Asia. Currently, antivenom therapy is the standard treatment for snakebite. However, antivenoms are not available in many rural countries and communities or have only limited effectiveness. Taiwan has wealth of experience in producing antivenoms, including the bivalent freeze-dried neurotoxic antivenom (FNAV), which is raised against venom proteins from Bungarus multicinctus and Naja atra. Our results showed that FNAV effectively neutralized the lethality of Naja kaouthia(Thailand) and Naja siamensis (Thailand) venoms, but not Ophiophagus hannah (Indonesia) venom, in an animal model. We further characterized the venom proteome profiles of the four cobras and identified three abundant proteins—neurotoxin, cytotoxin and phospholipase A2—in the venom of N. atra, N. kaouthia and N. siamensisas the major antigens recognized by FNAV. In contrast, we found that β-cardiotoxin and phospholipase A2, common toxin proteins in all king cobra venom samples, are weakly or not recognized by FNAV. Our data provide evidence suggesting the potential use of Taiwan’s FNAV to treat envenomation by other cobra species (N. kaouthia and N. siamensis) in Southeast Asia. Moreover, our findings support the previous recommendation and current experimental approach that major cobra toxins are used as antigens to generate more efficient antivenoms than those currently available.

Can Surgery in Patient with Protobothrops Mucrosquamatus Envenomation be Predicted in Emergency Department?

Objective

Protobothrops mucrosquamatus, a Crotalinae snake with haemorrhagic venom, is responsible for the most common poisoning snakebites in Taiwan. Although a specific antivenin has been developed to treat this snakebite, surgical intervention is still needed in some patients because of the progression of tissue injury. Early risk stratification is important to identify the early signs of need for surgery. The purpose of this study was to investigate the early predictors for surgery in patients with P. mucrosquamatus envenomation.

Methods

The medical records of inpatients with P. mucrosquamatus envenomation between 2008 and 2013 were retrospectively reviewed. Clinical information was collected and analysed between surgical and nonsurgical patients.

Results

A total of 60 patients with P. mucrosquamatus envenomation, including 8 surgical patients (13.3%) and 52 non-surgical patients (86.7%), presented to the emergency department during the study period. Compartment syndrome (62.5%) and tissue necrosis (37.5%) were the main reasons for surgery. Comparison between surgical and non-surgical patients showed significantly higher white blood cell count (17.1 × 103/μL vs. 8.5 × 103/μL; p=0.002) and peak D-dimer level (1924.8 ng/mL vs. 730.0 ng/mL; p=0.006) in the surgical group. Ecchymosis (p=0.009), haemorrhagic bulla formation (p=0.002), leukocytosis (p=0.002), elevated peak D-dimer level (>1000 ng/mL) (p=0.005), and rhabdomyolysis (creatine kinase level >1000 IU/L) (p=0.007) were the significant signs relevant to surgery. On multivariate analysis, leukocytosis and ecchymosis were the most significant predictors of surgery in patients with P. mucrosquamatus envenomation.

Conclusions

Patients with P. mucrosquamatus envenomation presenting with leukocytosis and wound ecchymosis will have a high probability of requiring surgical therapy. (Hong Kong j.emerg.med. 2016;23:210-219)

Contributing Factors for Complications and Outcomes in Patients With Snakebite: Experience in a Medical Center in Southern Taiwan

OBJECTIVES

Snakebite usually results in various complications, such as significant soft tissue damage, infection, hematological, and neurological deficit. Surgical intervention, usually, is indicated in patients with tissue necrosis, infection, and compartment syndrome. To identify the contributing factors for complications and outcomes in different patients with snakebite so that outcomes can be evaluated and treatment of such patients can be initiated at the earliest.

METHODS

Information was collected regarding age, sex, underlying disease, species of snake, and the course of treatment of the victims of snakebite who visited the emergency department of a medical center in southern Taiwan between 2004 and 2014. The data obtained were analyzed using SPSS 20.0.

RESULTS

The bites from Taiwan cobra (Naja naja atra) significantly resulted in more complications than those from other snakes and required surgical intervention. The use of antivenin and antibiotics, immediate presentation to the hospital, and the location of the bite also were significant contributing factors.

CONCLUSIONS

Taiwan cobra significantly results in higher possibility of prolonged hospitalization, operation, tissue necrosis, infection, and necrotizing fasciitis. Location of the bite, immediate presentation to the hospital, and use of antivenin and antibiotics affect the outcome of snakebite. Knowledge of these factors will help in a better management of patients with snakebite.

Naja atra snakebite in Taiwan

BACKGROUND

Naja atra snakebite is uncommon in Taiwan and causes distinct effects on its victims. Although the Taiwan government produces its own specific antivenom, little information on the management of N. atra snakebite is available.

MATERIALS AND METHODS

We retrospectively evaluated 183 patients admitted to two medical centers. Of these, 45 were identified as definite cases of N. atra snakebite, 86 as suspected cases, and 52 as clinical cases. Demographic data, symptomatology, and management were compared between these case groups.

RESULTS

Symptomatology and management were similar in the three groups. Among the 183 patients, 10 (5.5%) were asymptomatic and nine (4.9%) had transient and partial ptosis or body weakness. The principal effects were local tissue swelling and pain in 173 patients (94.5%), followed by clinically suspected wound infection in 148 (80.9%), skin necrosis in 120 (65.6%), necrotizing soft tissue infection in 77 (42.1%), fever in 59 (32.2%), and gastrointestinal effects in 53 (29%). The median total dose of specific antivenom needed to treat N. atra envenoming was 10 vials. In the envenomed patients, debridement was required in 74 patients (42.8%), fasciotomy/fasciectomy in 46 (26.6%), and finger or toe amputation in seven (4%). The first operation was performed at a median of 3.5 days after the bite.

DISCUSSION AND CONCLUSIONS

Based on these typical manifestations, clinical diagnosis of N. atra snakebites may be feasible and practical. In contrast to other snakes of Elapidae family, N. atra bite did not cause serious neurological effects. Early surgical consultation should be obtained because half of the patients underwent surgery due to infectious complications. Acute compartment syndrome was the surgical indication in rare cases; however, overestimation of the incidence may have occurred. This syndrome should be confirmed by serial intracompartmental pressure monitoring instead of only physical examination, and a sufficient dose of antivenom should be given prior to surgical decompression.

Envenoming by Viridovipera stejnegeri snake: a patient with liver cirrhosis presenting disruption of hemostatic balance

Background

In most cases of envenoming by the green habu Viridovipera stejnegeri in Taiwan coagulopathy is not observed.

Case presentation

Herein, we describe the case of a patient with liver cirrhosis who developed venom-induced consumptive coagulopathy after V. stejnegeri bite. Laboratory investigation revealed the following: prothrombin time > 100 s (international normalized ratio > 10), activated partial thromboplastin time > 100 s, fibrinogen < 50 mg/dL, and fibrin degradation product > 80 μg/mL. The patient recovered after administration of bivalent hemorrhagic antivenom, vitamin K, fresh frozen plasma and cryoprecipitate.

Conclusion

The liver, directly involved in the acute phase reaction, is the main responsible for neutralization of animal toxins. Any patient with history of liver cirrhosis bitten by a venomous snake, even those whose venoms present low risk of coagulopathy, should be very carefully monitored for venom-induced consumptive coagulopathy (VICC), since the hemostatic balance may be disrupted.

Aspirin plus tirofiban inhibit the thrombosis induced by Russell's viper venom

Background

Thrombosis and coagulopathy are the commonest hematological manifestations of envenomation of Russell’s viper venom (RVV). Factor X is activated by a factor X-activating enzyme from Russell’s viper venom (RVV-X) to start the coagulation cascade. We established an animal model with local ischemic effects induced by RVV. We tried to treat RVV envenomation with antiplatelets and anticoagulants without recourse to antivenom.

Methods

RVV was injected into the foot pad of mice. We observed the effects at different intervals and compared local changes in ischemia with drug treatment after 30 min.

Results

A combination of aspirin plus tirofiban could prevent the ischemic change induced by RVV. The antithrombotic effects of single-use of aspirin or tirofiban were better than single-use of heparin or clopidogrel.

Conclusion

The aspirin + tirofiban group had a better outcome with respect to prevention of tissue ischemia and gangrene. This indicates that the activation and aggregation of platelets is the major cause of thrombosis induced by RVV.

Predictors of the development of post-snakebite compartment syndrome

Background

To identify the factors associated with the development of post-snakebite compartment syndrome (PSCS) in snakebite patients and to analyze the clinical prognosis of these patients.

Methods

We retrospectively reviewed the medical records of patients who presented to our institution with snakebites from March 2009 to December 2012. The clinical data, hospital course and outcome were all recorded.

Results

A total of 136 patients were included in the present study. Nine patients developed PSCS and underwent fasciotomy. Relative to the non-PSCS group, the PSCS group demonstrated a significant increase in the white blood cell count (WBC, p = 0.006), segment form (Seg, p ≤ 0.001), aspartate aminotransferase level (AST, p = 0.002) and alanine aminotransferase level (ALT, p = 0.008). Elevated WBC count and AST level were identified as independent risk factors for PSCS (p = 0.028 and 0.037, respectively) in a multivariate analysis.

Conclusions

Snakebite patients have a high likelihood of developing locoregional complications such as PSCS. Symptomatic snakebite patients should be observed for at least 48 h, and increased WBC counts and AST levels are risk factors for PSCS.

High-resolution hyaluronidase inhibition profiling combined with HPLC-HRMS-SPE-NMR for identification of anti-necrosis constituents in Chinese plants used to treat snakebite

Inhibition of the necrotizing hyaluronidase, phospholipase A2 and protease enzymes in four snake venoms by crude water and ethanol extracts of 88 plant species used against snakebites in traditional Chinese medicine was measured. High-resolution hyaluronidase inhibition profiles were constructed for the 22 plants showing highest hyaluronidase inhibition, and the results were used to guide subsequent structural analysis towards specific hyaluronidase inhibitors. Structural analysis was performed by high-performance liquid chromatography, high-resolution mass spectrometry, solid-phase extraction and nuclear magnetic resonance spectroscopy, i.e., HPLC-HRMS-SPE-NMR. This allowed identification of four non-tannin inhibitors, i.e., lansiumamide B (6) from Clausena excavata Burm.f., myricetin 3-O-β-D-glucopyranoside (7) from Androsace umbellata (Lour.) Merr., and vitexin (8) and 4',7-dihydroxy-5-methoxyflavone-8-C-β-D-glucopyranoside (9) from Oxalis corniculata L. Absolute configuration of 2,3-dihydroxy-N-methyl-3-phenyl-N-[(Z)-styryl]propanamide (1) was determined using the Mosher method, which revealed two enantiomers, i.e., (2S,3R)-2,3-dihydroxy-N-methyl-3-phenyl-N-[(Z)-styryl]propanamide and (2R,3S)-2,3-dihydroxy-N-methyl-3-phenyl-N-[(Z)-styryl]propanamide with a ratio of 7:3.

Cobra venom proteome and glycome determined from individual snakes of Naja atra reveal medically important dynamic range and systematic geographic variation

Recent progress in snake venomics has shed much light on the intra-species variation among the toxins from different geographical regions and has provided important information for better snakebite management. Most previous reports on snake venomics were based on venoms pooled from different snakes. In this study, we present the proteomic and glycomic profiles of venoms from individual Naja atra snakes. The results reveal wide dynamic range of three-finger toxins. Systematic classification based on cardiotoxin (CTX-) profiles of A2/A4 and A6, respectively, allowed the identification of two putative subspecies of Taiwan cobra from the eastern and western regions. We also identified four major N-glycan moieties on cobra snake venom metalloproteinase on the bi-antennary glycan core. ELISA showed that these glycoproteins (<3%) could elicit much higher antibody response in antiserum when compared to other high-abundance cobra venom toxins such as small molecular weight CTXs (~60%). By removing these high-molecular weight glycoproteins from the immunogen, we demonstrated better protection than that achieved with conventional crude venom immunization in mice challenged by crude venom. We conclude that both intra-species and inter-individual variations of proteomic and glycomic profiles of snake venomics should be considered to provide better antivenomic approach for snakebite management.

BIOLOGICAL SIGNIFICANCE

Based on the proteomic and glycomic profiles of venoms obtained from individual snakes, we demonstrated a surprisingly wide dynamic range and geographical variation of three-finger toxins in cobra venomics. This provides a reasonable explanation for the variable neutralization effects of antivenom treatment on victims suffering from cobra snakebite and suggests a simple and economic method to produce potent antivenom with better efficacy. Since two major venomic profiles with distinct dynamic ranges were observed for Taiwan cobra venoms isolated from the eastern and western regions, the current venomic profile should be used as a quality control for future production of antivenom in clinical applications.

Envenoming by Crotalid Snake Chinese Moccasin Agkistrodon Acutus Bite – A Case Report

Although the bites caused by snakes from former Agkistrodon family in the areas of occurrence are not rare and even have certain epidemiologic importance, in case of envenoming by Deinagkistrodon acutus the clinical studies and case reports are very sporadic. This case report describes the envenoming of a private snake breeder bitten by young Chinese moccasin Deinagkistrodon acutus to the thumb of his left hand. He sought for a medical help immediately after snakebite. Patient presented with a local oedema on the affected limb, extending up to the half of the forearm. Laboratory examinations showed serious haemostatic disturbance with defibrination syndrome, immeasurably prolonged clotting times and extreme elevation of D-dimers. No other obvious clinical symptoms were present. Fibrinogen and fresh frozen plasma were administered because the antivenom was not available immediately. The specific antivenom was urgently imported 22 hours after the bite and administered at a dose of two vials three times until laboratory haemocoagulation parameters returned back to physiological values.

Rapid diagnosis of Naja atra snakebites

BACKGROUND

The clinical diagnosis of snakebites is critical and necessary in many parts of the world, especially in Southeastern Asia, where venomous snakebites are a burden on public health. It is difficult to define or recognize the species of venomous snake because of the overlapping clinical manifestations of envenomations. A quick and reliable method for identifying the snake species is necessary. We designed and tested a strip of lateral flow system for the diagnosis of cobra snake bites in Taiwan.

METHODS

We developed a kit based on an immunochromatographic method for rapid detection of cobra (Naja atra) venom in human serum. The test and control lines composed of 1 mg/ml polyclonal duck antivenom and 0.5 mg/ml goat anti-rabbit immunoglobulin antibody solutions, respectively, were coated on nitrocellulose strips. Colloidal gold was conjugated with rabbit polyclonal anti-cobra venom antibodies. From July 2007 to December 2012, we used the kit to test serum from snakebite patients and to examine the agreement between our rapid test and the currently used sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our kit was able to detect cobra venom in serum samples in 20 minutes with a detection limit of 5 ng/ml. An absence of cross-reactivity with other non-cobra venoms from Taiwan was noted in vitro. A total of 88 snakebite patients (34 cobra and 54 other non-cobra) were tested. The sensitivity of the strips based on the ELISA results was 83.3% and the specificity was 100%. There was a strong agreement between the results of the ELISA and immunochromatographic strips (κ = 0.868).

DISCUSSION AND CONCLUSIONS

This data indicates that an immunochromatographic strip might be suitable for cobra venom detection and could be used as a quick diagnostic tool in cases of N. atra snakebite.

Shewanella infection of snake bites: a twelve-year retrospective study

OBJECTIVE

Infections of snake bite wounds by Shewanella are rarely discussed in the medical literature. This study aims to characterize the presentation and management of Shewanella infections in snake bite wounds.

METHOD

We retrospectively investigated the microbiology, clinical features, and outcomes of patients with Shewanella infected snake bite wounds admitted to a tertiary medical center from January 1998 to December 2009.

RESULTS

Ten patients with Shewanella-infected snake bite wounds were identified. All of the snake bites were caused by cobras. The majority of patients had moderate to severe local envenomation and polymicrobial infections. Shewanella isolates are susceptible to ampicillin-sulbactam, piperacillin-tazobactam, third-and fourth-generation cephalosporins, carbapenems, aminoglycosides, and quinolones but are resistant to penicillin and cefazolin. All of the patients examined had favorable outcomes.

CONCLUSION

It is recommended that Shewanella infection be considered in snake bite patients, especially when patients present with moderate to severe local envenomation.

Bacterial infection in association with snakebite: a 10-year experience in a northern Taiwan medical center

BACKGROUND

Microbiological data of secondary wound infections following snakebites is rarely reported in Taiwan. The objective of this study was to assess the secondary wound infection after venomous snakebites.

METHODS

We conducted a 10-year retrospective survey on patients admitted for venomous snakebites and microbiological data of wound cultures at a medical center in northern Taiwan.

RESULTS

Between April 2001 and April 2010, 231 patients who experienced snakebites were included. Male predominated, accounting for 62.3% (144). The age range of patients was 4-95 years. Ninety-five (41.1%) people were bitten by Trimeresurus mucrosquamatus, followed by Tstejnegeri, and cobra. A total of 61 pathogens were obtained from 21 patients. Thirty-nine (63.9%) isolates were gram-negative bacteria, 14 (23%) gram-positive pathogens, and 8 (13.1%) anaerobic pathogens. There were 17 patients bitten by cobra in these 21 patients. Morganella morganii and Enterococcus species were the most common pathogens identified in the wound cultures.

CONCLUSION

Cobra bite causes more severe bacterial infection than other kinds of snakebites. Oral amoxicillin/clavulanate plus ciprofloxacin or parenteral piperacillin/tazobactam alone can be the choices for empirical or definitive treatment, and surgical intervention should be considered for established invasive soft tissue infections.

Antivenin-related serum sickness

Serum sickness is a type III hypersensitivity reaction that occurs due to the deposition of excessive circulating immune complexes in patients treated with foreign proteins or haptens. Serum sickness induced by antivenin for snakebites has been frequently reported in the USA, but not in Taiwan. This difference may be due to the efficacy and dosage of antivenins administered to treat snakebites in Taiwan. We report a case presenting with serum sickness after receiving a total of 20 vials of polyvalent antivenin therapy for the treatment of snakebite. A 59-year-old male suffered from fever, headaches, polyarthritis, and diffused skin rash approximately 10 days after administration of the antivenin. The large dose of antivenin administered in this case might have been the cause of the development of serum sickness. Physicians should be aware of the potential for serum sickness in cases of large-dose antivenin use.

A locally developed snakebite management protocol significantly reduces overall anti snake venom utilization in West Bengal, India

OBJECTIVE

The purpose of this study was to determine the impact of a nationally developed snakebite treatment protocol on the amount of anti snake venom (ASV) used in treating snakebites in a developing country and its effect on mortality. In addition, basic epidemiology data were collected and analyzed.

METHODS

Experts in Indian snakebites developed a protocol specifically designed for snakebite treatment in India. A training program was implemented in Midnapore Medical College in West Bengal, India, under the direction of the Health Minister to train care providers in the new protocol. After training, data were collected for 839 snakebite victims over a 12-month period and included epidemiological data, ASV volumes administered, and mortality. The results were collated and compared with results calculated from 780 snakebite victims treated during the 12-month period before implementation of the protocol. Treatment prior to protocol implementation was based on knowledge gained by the care providers from western and forensic medicine textbooks.

RESULTS

Protocol-guided treatment resulted in a 66% decline in the amount of ASV administered to victims. Fewer victims received ASV based on rational guidelines for assessing envenomation, dosage and repeat dosage, and clear endpoints to ASV therapy. In addition, there was a trend towards reduced mortality and an absolute reduction of 24%.

CONCLUSION

Use of the protocol reduced ASV utilization and the number of deaths. Locally developed protocols should be encouraged by such organizations as the World Health Organization and national and state governments and should be established with significant input from local experts.

Antivenom treatment and renal dysfunction in Russell's viper snakebite in Taiwan: a case series

Formosan Russell's viper (Daboia russelli siamensis) is the sixth most frequent cause of snakebites in Taiwan. Its bite induces greater kidney injury than other Russell's vipers in Southeast Asia. Poor availability of antivenom might be the major reason. To enhance treatment, we supplied the antivenom to the teaching hospitals that are near the areas where D. r. siamensis is found. We also used an ELISA in diagnosis. From June 1999 to December 2001, a total of 13 cases of D. r. siamensis snakebite were diagnosed with serum venom level of 10-98 ng/ml, 1-6 hours after being envenomed. Abnormal coagulation function and acute renal failure occurred early and were the two most important clinical features. Early specific antivenom treatment, 3-6 hours after systemic envenoming, restored the coagulation function in 1-2 days and seemed to be statistically effective in reducing the severity of renal damage compared with the historical and delayed group by the Wilcoxon rank-sum test. Two to four vials of antivenom were needed to block the systemic toxicity and produced few side effects. The antivenom should be administered as early as possible to prevent systemic dysfunction.