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Snake envenomation is a major public health problem in Brazil. Systemic complications that may arise from snakebites are mainly related to coagulopathy. The Lee-White clotting time (LWCT) is a simple and inexpensive test and available even in remote health facilities. However, the diagnostic value of such test needs to be evaluated to accurately di...
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Background
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Objectives
Brazil is home to large variety of snake species, of which about 17% are venomous. A large proportion of reported snakebite accidents in the country take place in northeast Brazil. We aimed to analyse the epidemiology of snakebites as a public health concern in Rio Grande do Norte state.
Methods
A retrospective epidemiologic analysis wa...
Citations
... Further, the thrombogenic method exhibits a shorter clotting time for BG (Na-free) than the UV absorption method. Similarly, the hemoclot activity was studied at room temperature using the thrombogenic activity and Le and White method 32 were shown in Supplementary Fig. S2a,b, and the clot duration was calculated and presented in Table 1. Ca ions in 45S5 BG play a vital role in coagulation by stimulating the development of clotting factors (IV) thrombin and fibrin 33 . ...
Bioactive glass (BG) is an interesting topic in soft tissue engineering because of its biocompatibility and bonding potential to increase fibroblast cell proliferation, synthesize growth factors, and stimulate granulation tissue development. The proposed BG with and without sodium (Na), prepared by the sol–gel method, is employed in wound healing studies. The BG/graphene oxide (GO) and BG (Na-free)/GO nanocomposites were investigated against fibroblast L929 cells in vitro; the 45S5 BG nanocomposites exhibited desired cell viability (80%), cell proliferation (30%), cell migration (25%), metabolic activity, and wound contraction due to extracellular matrix (ECM) production and enhanced protein release by fibroblast cells. Additionally, the antioxidant assays for BG, BG (Na-free), GO, and BG/GO, BG (Na-free)/GO were evaluated for effective wound healing properties. The results showed decreased inflammation sites in the wound area, assessed by the (2,2-diphenyl-1-picryl-hydrazyl-hydrate) (DPPH) assay with ~ 80% radical scavenging activity, confirming their anti-inflammatory and improved wound healing properties.
... Our study demonstrated the hemostatic property using the Lee-White method for clotting time [39]. The time difference between the formation of the clot in the presence of the gelatin sponge and the Calendula officinalis loaded gelatin sponge was 2.97 ± 2.78 s. ...
Excessive bleeding can complicate surgical intervention; this could be managed using an effective hemostatic agent that provides immediate and early bleeding control. Gelatin sponge and Calendula officinalis have been proven to have good hemostatic properties. The present In-vitro study analyzed the cytotoxicity and hemostatic properties of gelatin sponge and Calendula officinalis. The cytotoxic concentration/effective concentration of Calendula officinalis was determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. The drug release was determined using a vertical Franz diffusion cell apparatus; solid-state characterization was assessed using Fourier-transform infrared spectroscopy (FTIR) and a differential scanning calorimeter (DSC). The MTT assay showed 7% Calendula officinalis to be cytocompatible, and there was an increase in cell proliferation. When the 7% Calendula officinalis was loaded into the sponge, it was compatible, and the drug content was found to be 56.28 ± 13.84%. The time taken for the blood clot formation was measured using the Lee–White method. The gelatin sponge’s time for clot formation was 161.70 ± 3.11 s, and the Calendula officinalis loaded gelatin sponge’s time for clot formation was 158.75 ± 4.60 s. Hence, it could be concluded that when Calendula officinalis is incorporated into a gelatin sponge, it shows material compatibility and cytocompatibility, reduces the time for clot formation, and could be used as an alternative to other hemostatic agents.
... The clotting time of the nanoparticle treated samples was similar to the negative control (p = 0.07). The normal value of clotting time is 5-10 min and our study results complied with this range [57]. This study indicates that the nanoparticles did not interfere with the blood clotting mechanism. ...
Anemia is the most common hematological abnormality of chemotherapy, which is responsible for poor clinical outcomes. To overcome this complication, the present study was aimed for developing a Eudragit/polylactic-co-glycolic acid (PLGA) based nanoparticulate system for a model drug paclitaxel (PTX). The study was planned using a simplex lattice mixture design. PTX nanoparticles (PTXNp) were evaluated in vitro for physicochemical properties, hemolytic effects and cytotoxic effects. Further, the nanoparticles were subjected to in vivo screening using rats for hemocompatibility, pharmacokinetic profile, and biodistribution to the vital organs. The PTXNps were 65.77–214.73 nm in size, showed more than 60% sustained drug release in 360 h and caused less than 8% hemolysis. The parameters like red blood cell count, activated partial thromboplastin time (aPTT), prothrombin time (PT) and C3 complement were similar to the negative control. Cytotoxicity results suggested that all the PTXNp demonstrated drug concentration-dependent cytotoxicity. The in vivo pharmacokinetic study concluded that PTXNp formulations had significantly higher blood AUC (93.194.55–163,071.15 h*ng/mL), longer half-lives (5.80–6.35 h) and extended mean residence times (6.05–8.54 h) in comparison to PTX solution (p < 0.05). Overall, the study provides a nanoparticulate drug delivery system to deliver PTX safely and effectively along with reducing the associated hematological adverse effects.
... Unfortunately, as most snakebites occur in remote geographical locations, conventional clotting assays are not commonly available. As a result, a number of bedside tests are used to detect clotting abnormalities-these include the 20-minute whole blood clotting test (20WBCT) [4], 30-minute whole blood clotting test (30WBCT) [13], capillary blood clotting time [14], Lee-White clotting test [15] and Vellore manual activated clotting time (VeMac) [16]. The 20WBCT is the most widely used bedside clotting test in snakebite envenoming and is recommended by two WHO snakebite management guidelines [17,18]. ...
... Whilst the discrepancy in results underlines the importance of external validation, considerable differences may be expected if the index test (20WBCT) and reference test (INR) are collected non-synchronously, particularly given the dynamic process of haemostasis. The former study [43], which raised concerns that the 20WBCT lacks sensitivity [15,44], analysed unpaired 20WBCT and INR samples collected at different time-points and showed a lower sensitivity to the studies in this systematic review, that used paired samples. ...
Background
The 20-minute whole blood clotting test (20WBCT) has been used to detect coagulopathy following snakebite for almost 50 years. A systematic review and meta-analysis of the 20WBCT was conducted to evaluate the accuracy of the 20WBCT to detect coagulopathy, indicative of systemic envenoming.
Methods and findings
Databases were searched from inception up to 09/12/2020 to identify studies that compared the 20WBCT and INR/fibrinogen on five or more subjects. Data was extracted from full-text articles by two reviewers using a predetermined form. Authors of 29 studies that lacked sufficient details in the manuscript were contacted and included if data meeting the inclusion criteria were provided. Included studies were evaluated for bias using a tailored QUADAS-2 checklist. The study protocol was prospectively registered on PROSPERO database (CRD42020168953).
The searches identified 3,599 studies, 15 met the inclusion criteria and 12 were included in the meta-analysis. Data was reported from 6 countries and included a total of 2,270 patients. The aggregate weighted sensitivity of the 20WBCT at detecting INR >1.4 was 0.84 (CI 0.61 to 0.94), the specificity was 0.91 (0.76 to 0.97) and the SROC AUC was 0.94 (CI 0.91 to 0.96). The aggregate weighted sensitivity of the 20WBCT at detecting fibrinogen <100 mg/dL was 0.72 (CI 0.58 to 0.83), the specificity was 0.94 (CI 0.88 to 0.98) and the SROC AUC was 0.93 (0.91 to 0.95). Both analyses that used INR and fibrinogen as the reference test displayed considerable heterogeneity.
Conclusions
In the absence of laboratory clotting assays, the 20WBCT remains a highly specific and fairly sensitive bedside test at detecting coagulopathy following snakebite. However, clinicians should be aware of the importance of operator training, standardized equipment and the lower sensitivity of the 20WBCT at detecting mild coagulopathy and resolution of coagulopathy following antivenom.
... In Mexico, where rattlesnakes are the predominant genus, the Lee-White clotting time (LWCT) is utilized to determine the presence of coagulation disorders, which can in turn give an indication of the urgency of commencing treatment (180). LWCT is fundamentally similar to the 20WBCT described earlier, with the only difference being that the LWCT is observed once per minute after an initial incubation time of five minutes (181). The effectiveness of LWCT was assessed in Brazil for its sensitivity toward detecting coagulopathy in lancehead envenomings and was considered a valuable tool in evaluating the need for antivenom therapy (181). ...
... LWCT is fundamentally similar to the 20WBCT described earlier, with the only difference being that the LWCT is observed once per minute after an initial incubation time of five minutes (181). The effectiveness of LWCT was assessed in Brazil for its sensitivity toward detecting coagulopathy in lancehead envenomings and was considered a valuable tool in evaluating the need for antivenom therapy (181). ...
Snakebite envenoming is predominantly an occupational disease of the rural tropics, causing death or permanent disability to hundreds of thousands of victims annually. The diagnosis of snakebite envenoming is commonly based on a combination of patient history and a syndromic approach. However, the availability of auxiliary diagnostic tests at the disposal of the clinicians vary from country to country, and the level of experience within snakebite diagnosis and intervention may be quite different for clinicians from different hospitals. As such, achieving timely diagnosis, and thus treatment, is a challenge faced by treating personnel around the globe. For years, much effort has gone into developing novel diagnostics to support diagnosis of snakebite victims, especially in rural areas of the tropics. Gaining access to affordable and rapid diagnostics could potentially facilitate more favorable patient outcomes due to early and appropriate treatment. This review aims to highlight regional differences in epidemiology and clinical snakebite management on a global scale, including an overview of the past and ongoing research efforts within snakebite diagnostics. Finally, the review is rounded off with a discussion on design considerations and potential benefits of novel snakebite diagnostics.
... One study reports that an abnormal clotting time was found in 100% of Echis carinatus victims, who presented any sign or symptoms of envenoming, and in the only two cases of dry bites, the clotting time was normal [63,71]. In Manaus, out of 186 patients with Bothrops envenoming, 75.3% had prolonged clotting times, and 85.5% had hypofibrinogenemia [72]. Systemic envenoming by juvenile C. durissus terrificus resulted in coagulopathy as the main systemic Toxins 2020, 12, 668 9 of 20 manifestation without other features normally associated with this type of specimens [73]. ...
Snake 'dry bites' are characterized by the absence of venom being injected into the victim during a snakebite incident. The dry bite mechanism and diagnosis are quite complex, and the lack of envenoming symptoms in these cases may be misinterpreted as a miraculous treatment or as proof that the bite from the perpetrating snake species is rather harmless. The circumstances of dry bites and their clinical diagnosis are not well-explored in the literature, which may lead to ambiguity amongst treating personnel about whether antivenom is indicated or not. Here, the epidemiology and recorded history of dry bites are reviewed, and the clinical knowledge on the dry bite phenomenon is presented and discussed. Finally, this review proposes a diagnostic and therapeutic protocol to assist medical care after snake dry bites, aiming to improve patient outcomes.
... Those results suggest at least a partial efficacy of AV Antivipmyn Tri ® to reverse coagulation disorders after SB without a strong difference between the two dosage regimens used. A recent study on the use of the same antivenom in snake-bitten patients attended to in the Guianese western hospital did not reveal differences in the time needed to restore coagulation parameters between patients receiving three vials of antivenom and patients that did not receive antivenom [20]. The reasons for this discrepancy remain to be determined. ...
... In the case of lethal activity, Antivipmyn Tri ® did not neutralize the effect at the highest antivenom level tested (1 mg venom/mL antivenom). A previous study indicated that the dose of three vials is insufficient, especially in grade 2 or 3 cases, since no improvement in the correction of coagulation parameters was observed [20]. ...
The management of snakebite (SB) envenoming in French Guiana (FG) is based on symptomatic measures and antivenom (AV) administration (Antivipmyn Tri®; Instituto Bioclon—Mexico). Our study aimed to assess clinical manifestations, the efficacy, and safety of Antivipmyn Tri® in the management of SB. Our study is a prospective observational work. It was conducted in the Intensive Care Unit (ICU) of Cayenne General Hospital between 1 January 2016 and 31 December 2019. We included all patients hospitalized for SB envenoming. Our study contained three groups (without AV, three vials, and six vials Antivipmyn Tri®). During the study period, 133 patients were included. The main clinical symptoms were edema (98.5%), pain (97.7%), systemic hemorrhage (18%), blister (14.3%), and local hemorrhage (14.3%). AV was prescribed for 83 patients (62.3%), and 17 of them (20%) developed early adverse reactions. Biological parameters at admission showed defibrinogenation in 124 cases (93.2%), International Normalized Ratio (INR) > 2 in 104 cases (78.2%), and partial thromboplastin time (PTT) > 1.5 in 74 cases (55.6%). The time from SB to AV was 9:00 (5:22–20:40). The median time from SB to achieve a normal dosage of fibrinogen was 47:00 vs. 25:30, that of Factor II was 24:55 vs. 15:10, that of Factor V was 31:42 vs. 19:42, and that of Factor VIII was 21:30 vs. 10:20 in patients without and with AV, respectively, (p < 0.001 for all factors). Patients receiving Antivipmyn Tri® showed a reduction in the time to return to normal clotting tests, as compared to those who did not. We suggest assessing other antivenoms available in the region to compare their efficacy and safety with Antivipmyn Tri® in FG.
... The search did not identify a study that has evaluated, validated or used the original Lee-White method in the diagnosis of VICC. However, a slightly modified Lee-White clotting time has been used in diagnosing VICC in Bothrops atrox-envenomed patients from Brazil [22,23]. This modified test is performed by placing 1 mL of venous blood in a glass tube and leaving it undisturbed for 5 min. ...
... Following this, the tube is gently tilted every minute and the clotting time is taken when clot formation is observed. Although it is not clear how it was determined, the upper limit of time that is normal for this modified Lee-White clotting test has been defined as 9 min [23]. In Bothrops atrox-envenomed patients, the modified Lee-White clotting method was shown to have a sensitivity of 78% and a specificity of 40.7% compared to fibrinogen concentrations (>200 mg/dL was considered to be normal), when performed by laboratory technicians. ...
... In Bothrops atrox-envenomed patients, the modified Lee-White clotting method was shown to have a sensitivity of 78% and a specificity of 40.7% compared to fibrinogen concentrations (>200 mg/dL was considered to be normal), when performed by laboratory technicians. During this study, it was noted that mild VICC may be present even with a negative modified Lee-White clotting time result [23]. ...
Venom-induced consumption coagulopathy is the most important systemic effect of snake envenoming. Coagulation tests are helpful to accurately and promptly diagnose venom-induced consumption coagulopathy and administer antivenom, which is the only specific treatment available. However, bedside clotting tests play a major role in diagnosing coagulopathy in low-income settings, where the majority of snakebites occur. We conducted a literature search in MEDLINE® from 1946 to 30 November 2019, looking for research articles describing clinical studies on bedside coagulation tests in snakebite patients. Out of 442 articles identified, 147 articles describing bedside clotting assays were included in the review. Three main bedside clotting tests were identified, namely the Lee-White clotting test, 20-min whole blood clotting time and venous clotting time. Although the original Lee-White clotting test has never been validated for snake envenoming, a recently validated version has been used in some South American countries. The 20-min whole blood clotting time test is the most commonly used test in a wide range of settings and for taxonomically diverse snake species. Venous clotting time is almost exclusively used in Thailand. Many validation studies have methodological limitations, including small sample size, lack of case-authentication, the inclusion of a heterogeneous mix of snakebites and inappropriate uses of gold standard tests. The observation times for bedside clotting tests were arbitrary, without proper scientific justification. Future research needs to focus on improving the existing 20-min whole blood clotting test, and also on looking for alternative bedside coagulation tests which are cheap, reliable and quicker.
... The mechanism of coagulopathy has been widely explored in the literature [45]. Indeed, hypofibrinogenemia is a major systemic complication from Bothrops snakebites, affecting more than 80% of the patients [55]. This condition results from the action of serine proteinases having thrombin-like activity, which converts fibrinogen to fibrin, and also to the procoagulant activity of metalloproteinases, which activate factors II and X of the coagulation cascade, resulting in the formation of endogenous thrombin [56]. ...
... The involved enzymes are PI and P-III snake venom metalloproteinases (examples are batroxase [59], Atroxlysin-Ia [60], and Batroxrhagin [42]). Systemic bleeding observed in Bothrops snakebites was reported in 3.6-15.3% of patients [55,61]. It includes gingival bleeding, subconjunctival hemorrhage, hematuria and, in severe cases, cerebral hemorrhage. ...
Purpose of Review
Snakebite envenoming is a neglected tropical disease with a high burden in the Amazon basin. Our review aimed to give information about the epidemiology and the management of SB in the Amazon region.
Recent Findings
The Amazon basin, which comprises the largest portion of tropical rainforest on earth, includes territories of nine South American countries. The Amazon harbors a rich herpetofauna, among which the species of the Bothrops genus (family Viperidae) cause the highest number of bites and envenomings. The management of snakebite envenomings poses a difficult challenge for the public health systems of these countries for several reasons: bites occur in remote rural locations far from urban centers and health facilities; there are transportation difficulties for; health posts and personnel are in insufficient numbers; and antivenoms are insufficiently available in some regions. In addition, the species causing the highest number of accidents, i.e. Bothrops atrox, often causes severe envenomings.
Summary
The present review summarizes the main aspects of envenomings by Bothrops sp. snakes in the Amazonia, including the epidemiology, pathophysiology, clinical manifestations, and therapy of envenomings. In a context of global efforts to reduce the impact of snakebite envenomings, there is a need for international cooperative efforts by public health authorities and civil society in these countries.
... B. atrox venom includes metalloproteinase as the major toxin family followed by phospholipases A 2 , serine proteinases, cysteine-rich secretory proteins, L-amino acid oxidases and C-type lectin-like toxins [4][5][6]. Hypofibrinogenemia is a major systemic complication from B. atrox bites, affecting more than 80% of the patients [7]. This condition results from the action of serine proteinases having thrombin-like activity, which converts fibrinogen to fibrin, and also due to the procoagulant activity of metalloproteinases, which activate factors II and X of the coagulation cascade, resulting in the formation of endogenous thrombin [8]. ...
... In addition, PI and P-III metalloproteinases, such as batroxase [9], Atroxlysin-Ia [10] and Batroxrhagin [11], cause microvascular damage by proteolytic degradation of basement membrane [12]. These processes combined are responsible for systemic bleeding observed in B. atrox snakebites [7,13]. ...
... The tube was left undisturbed for 5 min and then checked for clots every minute by gently tilting the tube. Unclottable blood was defined when the blood was not clotted until 10 min [7]. Thrombocytopenia was defined as platelet counts <150,000 platelets/mL. ...
Introduction: Snake venom composition shows significant inter- and intra-species variation. In the case of the viperid species Bothrops atrox, responsible for the majority of snakebites in the Amazon region, geographical and ontogenetic variables affect venom composition, with ecological and medical implications. Previous studies had shown that venom from neonate and juvenile Bothrops specimens have a higher in vitro coagulant activity. The aim of this investigation was to assess the association of clinical outcomes, such as venom-induced coagulopathy and local complications, with B. atrox ontogenetic variables.
Methods: This study explored the relationship between some clinical parameters in patients suffering envenomations by B. atrox in the Amazon and several morphometric parameters of the snake specimens causing the bites.
Results: There were 248 specimens confirmed as agents of envenomation, mostly female snakes (70.5%) and classified as juveniles (62.7%). Patients bitten by neonates compared to adult snakes [OR = 2.70 (95%CI 1.15-6.37); p = .021] and by snakes with white tail tip [OR = 1.98 (95%CI 1.15–3.41); p = .013] were more likely to develop coagulopathy. Time from patient admission to the unclottable blood reversion was not affected by the snake gender (p = .214) or age (p = .254). Patients bitten by neonate (p = .024) or juvenile snakes (p < .0001) presented a lower frequency of moderate to severe edema, as compared to those bitten by adult snakes. In agreement with experimental observations, patients bitten by neonates and by snakes with a white tail tip were more likely to develop coagulopathy than those bitten by adult snakes. In contrast, envenomations by adult snakes were associated with a higher incidence of severe local edema.
Conclusion: Despite these variations, no difference was observed in the time needed to recover blood clotting in these patients after Bothrops antivenom administration.
