Low dose of snake antivenom is as effective as high dose in patients with severe neurotoxic snake envenoming

Assessing Target Specificity of the Small Molecule Inhibitor MARIMASTAT to Snake Venom Toxins: A Novel Application of Thermal Proteome Profiling

New treatments that circumvent the pitfalls of traditional antivenom therapies are critical to address the problem of snakebite globally. Numerous snake venom toxin inhibitors have shown promising cross-species neutralization of medically significant venom toxins in vivo and in vitro. The development of high-throughput approaches for the screening of such inhibitors could accelerate their identification, testing, and implementation and thus holds exciting potential for improving the treatments and outcomes of snakebite envenomation worldwide. Energetics-based proteomic approaches, including thermal proteome profiling and proteome integral solubility alteration (PISA) assays, represent "deep proteomics" methods for high throughput, proteome-wide identification of drug targets and ligands. In the following study, we apply thermal proteome profiling and PISA methods to characterize the interactions between venom toxin proteoforms in Crotalus atrox (Western Diamondback Rattlesnake) and the snake venom metalloprotease (SVMP) inhibitor marimastat. We investigate its venom proteome-wide effects and characterize its interactions with specific SVMP proteoforms, as well as its potential targeting of non-SVMP venom toxin families. We also compare the performance of PISA thermal window and soluble supernatant with insoluble precipitate using two inhibitor concentrations, providing the first demonstration of the utility of a sensitive high-throughput PISA-based approach to assess the direct targets of small molecule inhibitors for snake venom.

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

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

Efficacy of a low dose of antivenom for severe neuroparalysis in Bungarus caeruleus (common krait) envenomation: a pilot study

Introduction

Despite the widespread use of antivenom for the treatment of snakebite envenoming in the Indian subcontinent, the ideal dose of antivenom has been a point of contention. Low-dose regimens can economize on a scarce resource in low- and middle-income countries. This study assessed the effectiveness of a low-dose (10 vials) antivenom regimen compared to the usual 20 vials in patients with krait bite neuroparalysis requiring mechanical ventilation.

Methods

This study was a prospective controlled pilot study conducted in a tertiary-care hospital in north India. Participants were eligible if they were ≥12 years old, had krait bite neurotoxicity, showed severe paralysis requiring mechanical ventilation, and had access to antivenom therapy within 24 h of the bite. The primary outcome was the duration of mechanical ventilation, and the secondary outcomes were the length of hospital stay and in-hospital survival.

Results

Fifteen patients received 10 vials of antivenom, and 25 received 20 vials. The two treatment groups had similar baseline demographics, clinical and laboratory features, snakebite severity scores, and median time from snakebite to initiation of antivenom therapy. The low-dose regimen was as effective as the standard dose concerning the median duration of mechanical ventilation (41 h vs. 55 h, P = 0.094), the median length of stay (78 h vs. 85.5 h, P = 0.360), and in-hospital deaths (1 vs. 3, P = 1.000). The incidence of ventilator-associated pneumonia was similar between the two groups (1 vs 3, P = 1.000).

Conclusion

A low dose of antivenom effectively treats patients with severe krait bite neuroparalysis.

Development, standardization, and contextualization of qualitative tools for possible use in the assessment and valuation of snakebite envenomation

Background

Snakebite envenoming, a neglected tropical disease (NTD), is an important public health problem that is responsible for more than 1 lakh deaths annually across the world. However, the majority of the data in this regard is from health institutions and data from community settings are scarce. The aim of the current study was to develop valid and reliable qualitative tools for assessing the burden of snakebites and the health-seeking behavior of the community. The tools developed thus will serve in creating a community connection and thereby strengthen primary care teams engaged in managing snakebites at the primary care level.

Methods

A four-step design was used; (a) review of the available literature on the burden of disease, tools used to assess the burden, and the guidelines on snakebite (b) development, laying out, and contextualization of questions/items for the tools (c) pilot testing and establishment of validity.

Results

A focus group discussion guide, key informant interview schedule for health professionals, community leaders, and traditional faith healers were matured for the implementation.

Conclusion

A reliable and valid qualitative tool was developed to discern the speculations related to snakebites and its management in rural field settings.

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.

Retrospective review of case records of snakebite presenting to a single tertiary care centre over a 5-year period

Background Snakebite is a disease of the poor, and hospitals catering to these individuals are often resource-constrained. Lack of electronic medical records in these resource-limited settings makes the capture of data even harder. Methods Before establishing a snakebite registry in the region, we did a retrospective case record review of all snakebite victims (n=3229) over 5 years who presented to a single tertiary care centre, catering to one of the largest number of snakebite victims in the country. Results Of the 451 cases, 262 (58.1%) presented to the emergency department within 2 hours of the bite. In 170 instances, the snake was brought along and the species of the snake was recorded. Russell's viper was the most common (130; 76.5%). Blood products were used in 237 (52.5%) patients. Acute kidney injury occurred in 165 (36.6%) patients, of whom 37 (8.2%) required dialysis. The mean (SD) duration of hospital admission was 10.5 (7.4) days. There was a significant correlation between number of snakebites with rainfall and humidity. One hundred and seven cases (3.3%) of snakebite resulted in mortality. A majority of mortality records were not available (88%; 94/107), rendering us incapable of doing reliable mortality data correlations or interpretation. Conclusion Viperidae bites predominate in the region, with renal injury being the most common cause for morbidity. Region-specific, prospective snakebite mapping could be a cost-effective strategy that might help in vulnerability analysis of the region. A multi-centric region-specific snakebite registry encompassing not just the clinico-epidemiological characteristics of snakebite victims, but also the demographic data, the pre-hospital care and local remedial practices, geospatial distribution, anti-snake venom and blood product usage, will help in developing better healthcare strategies for snakebite victims in India.

Clinical profile & complications of neurotoxic snake bite & comparison of two regimens of polyvalent anti-snake venom in its treatment

Background & objectives:

The optimal anti-snake venom (ASV) dose required to treat neurotoxic snake envenomation is not known. Low-dose ASV (national protocol: maximum dose 200 ml) may be as efficacious as the conventional regimen (100 ml six hourly till all symptoms disappear), but a direct comparison of the regimens is not available. The aim of this study was to test the efficacy of low-dose ASV regimen against the conventional high-dose regimen.

Methods:

The clinical profile of 51 patients with neurotoxic snake envenomation was studied. Patients were treated with either the national protocol or the conventional protocol for ASV administration. The time to complete recovery of symptoms, duration of mechanical ventilation and total dose of ASV were compared.

Results:

More patients were females (28 vs. 23) bitten in the early morning hours (2400-0600 h). Thirty nine of 51 (76.4%) patients required mechanical ventilation. In terms of progression of neuroparalysis, time to complete resolution of ptosis and occurrence of VAP and ASV reactions, there was no difference. Duration of mechanical ventilation was less with the national protocol (24 vs. 43.5 h). Significantly less amount of ASV was used with the national protocol (224 vs. 982 ml) per patient. There were no mortality or permanent neurological sequelae with either regimen.

Interpretation & conclusions:

In this preliminary study, it was found that the national ASV protocol was as effective as the conventional regimen for neurotoxic snake bites. However, the findings need to be tested in a larger randomized controlled trial for definitive conclusions.

Comparison of Different Dosing Protocols of Anti-Snake Venom (ASV) in Snake Bite Cases

Introduction

Considering the cost of Anti-Snake Venom (ASV) and irregularity in its supply, there is often a need to curtail doses of ASV, despite guidelines for management of snake bite. During June 2013 to September 2013, when ASV was in short supply, our institutional committee reviewed the overall hospital statistics of snake bite cases as well as scientific literature and formulated a working modified protocol that used low dose of ASV in snake bite cases.

Aim

To retrospectively analyse and compare the modified ASV protocol versus conventional ASV protocol with respect to outcome, number of ASV vials required, duration of stay in the hospital/ ICU, and additional supportive interventions needed.

Materials and Methods

This was a retrospective study conducted at a tertiary care teaching hospital, Maharashtra, India. Hospital records of inpatients admitted for snake bite during June 2013 to September 2013 (since introduction of the modified protocol) as well as during June 2012 to September 2012, (when patients received conventional protocol-historical controls) were retrospectively analysed to assess the number of ASV vials received by the patients during the stay, need for supportive therapy, duration of stay and outcome of the patients.

Results

There was a significant reduction in average number of ASV vials per patient, required vide the modified protocol compared to their historical controls (10.74±0.95 vs 28.17±2.75 p<0.001). There was no significant difference in outcome, need for dialysis, fresh frozen plasma requirement, need for ICU stay and duration of hospitalization of snake bite patients. Yet, the average cost of management of each patient reduced by approximately 11974.41 INR per treated patient, based on the requirement of ASV.

Conclusion

The modified ASV protocol used in this study is more cost effective as compared to the conventional protocol, deserves prospective evaluation and may be followed at least during prime time of scarcity of ASV.

Dose of antivenom for the treatment of snakebite with neurotoxic envenoming: Evidence from a randomised controlled trial in Nepal

BACKGROUND

Currently, there is inadequate evidence on which to base clinical management of neurotoxic snakebite envenoming, especially in the choice of initial antivenom dosage. This randomised controlled trial compared the effectiveness and safety of high versus low initial antivenom dosage in victims of neurotoxic envenoming.

METHODOLOGY/ PRINCIPAL FINDINGS

This was a balanced, randomised, double-blind trial that was conducted in three health care centers located in the Terai plains of Nepal. Participants received either low (two vials) or high (10 vials) initial dosage of Indian polyvalent antivenom. The primary composite outcome consisted of death, the need for assisted ventilation and worsening/recurrence of neurotoxicity. Hourly evaluations followed antivenom treatment. Between April 2011 and October 2012, 157 snakebite victims were enrolled, of which 154 were analysed (76 in the low and 78 in the high initial dose group). Sixty-seven (43·5%) participants met the primary outcome definition. The proportions were similar in the low (37 or 48.7%) vs. high (30 or 38.5%) initial dose group (difference = 10·2%, 95%CI [-6·7 to 27·1], p = 0·264). The mean number of vials used was similar between treatment groups. Overall, patients bitten by kraits did worse than those bitten by cobras. The occurrence of treatment-related adverse events did not differ among treatment groups. A total of 19 serious adverse events occurred, including seven attributed to antivenom.

CONCLUSIONS

This first robust trial investigating antivenom dosage for neurotoxic snakebite envenoming shows that the antivenom currently used in Nepal performs poorly. Although the high initial dose regimen is not more effective than the low initial dose, it offers the practical advantage of being a single dose, while not incurring higher consumption or enhanced risk of adverse reaction. The development of new and more effective antivenoms that better target the species responsible for bites in the region will help improve future patients' outcomes.

TRIAL REGISTRATION

The study was registered on clinicaltrials.gov (NCT01284855) (GJ 5/1).

Antivenom for Neuromuscular Paralysis Resulting From Snake Envenoming

Antivenom therapy is currently the standard practice for treating neuromuscular dysfunction in snake envenoming. We reviewed the clinical and experimental evidence-base for the efficacy and effectiveness of antivenom in snakebite neurotoxicity. The main site of snake neurotoxins is the neuromuscular junction, and the majority are either: (1) pre-synaptic neurotoxins irreversibly damaging the presynaptic terminal; or (2) post-synaptic neurotoxins that bind to the nicotinic acetylcholine receptor. Pre-clinical tests of antivenom efficacy for neurotoxicity include rodent lethality tests, which are problematic, and in vitro pharmacological tests such as nerve-muscle preparation studies, that appear to provide more clinically meaningful information. We searched MEDLINE (from 1946) and EMBASE (from 1947) until March 2017 for clinical studies. The search yielded no randomised placebo-controlled trials of antivenom for neuromuscular dysfunction. There were several randomised and non-randomised comparative trials that compared two or more doses of the same or different antivenom, and numerous cohort studies and case reports. The majority of studies available had deficiencies including poor case definition, poor study design, small sample size or no objective measures of paralysis. A number of studies demonstrated the efficacy of antivenom in human envenoming by clearing circulating venom. Studies of snakes with primarily pre-synaptic neurotoxins, such as kraits (Bungarus spp.) and taipans (Oxyuranus spp.) suggest that antivenom does not reverse established neurotoxicity, but early administration may be associated with decreased severity or prevent neurotoxicity. Small studies of snakes with mainly post-synaptic neurotoxins, including some cobra species (Naja spp.), provide preliminary evidence that neurotoxicity may be reversed with antivenom, but placebo controlled studies with objective outcome measures are required to confirm this.

High-dose versus low-dose antivenom in the treatment of poisonous snake bites: A systematic review

Though snake antivenom (SAV) is the mainstay of therapy for poisonous snake bites, there is no universally accepted standard regimen regarding the optimum dose (low vs. high). We therefore, undertook this systematic review to address this important research question. We searched all the published literature through the major electronic databases till August 2014. Randomized clinical trials (RCTs) were included. Eligible trials compared low versus high dose SAV in poisonous snake bite. The review has been registered at PROSPERO (Registration number: CRD42014009700). Of 36 citations retrieved, a total of 5 RCTs (n = 473) were included in the final analyses. Three trials were open-label, 4 conducted in Indian sub-continent and 1 in Brazil. The doses of SAV varied in the high dose group from 40 ml to 550 ml, and in the low dose group from 20 ml to 220 ml. There was no significant difference between the two groups for any of the outcomes except duration of hospital stay, which was lower in the low dose group. The GRADE evidence generated was of "very low quality." Low-dose SAV is equivalent or may be superior to high-dose SAV in management of poisonous snake bite. Low dose is also highly cost-effective as compared to the high dose. But the GRADE evidence generated was of "very low quality" as most were open label trials. Further trials are needed to make definitive recommendations regarding the dose and these should also include children <9 years of age.

Pulmonary effects and complications of snakebites

This review is on the pulmonary complications of snakebites, which can have fatal consequences. We identified three common themes as reported in the literature regarding envenomation: generalized neuromuscular paralysis affecting airway and respiratory muscles, pulmonary edema, and pulmonary hemorrhages or thrombosis due to coagulopathy. Respiratory paralysis and pulmonary edema can be due to either elapid or viper bites, whereas pulmonary complications of coagulopathy are exclusively reported with viper bites. The evidence for each complication, timeline of appearance, response to treatment, and details of pathophysiology are discussed.

Judicious use of antisnake venom in the present period of scarcity

Context:

Although antisnake venom (ASV) has been used for many years, selection of an optimal dose is a debated issue due to acute shortage of ASV in India. Despite evidence for smaller doses, most centers still use conventional doses.

Aims:

This study aimed to evaluate the effects of two different dosage regimens on the outcome of patients with snake envenomation, using a retrospective descriptive analysis of patient records admitted in our hospital.

Settings and Design:

A retrospective descriptive case series study was conducted from hospital records consisting 155 snakebite patients from June 2013 to January 2014.

Materials and Methods:

Patients were divided into two groups: Low dose ASV group (received <10 vials) and high dose ASV group (received ≥10 vials). Various complications were compared among these two groups.

Results:

The mean dose of ASV used in high dose, and low-dose group was 14.7 ± 5.3 and 4.2 ± 2.3, respectively. In low dose group, 20.5% of patients had acute kidney injury, whereas it was 10.9% in high dose group. In low dose group, 12.3% patients had neuroparalysis severe enough to require ventilator support and mortality rate was 5.5% which was comparable to the high-dose group (15.8% had neuroparalysis requiring ventilator support and a mortality rate of 8.5%).

Conclusion:

This study demonstrated that the low dose ASV regimen in poisonous snake bites along with supportive treatment as necessary is as efficacious as high dose regimen and has comparable complications.

Snakebite profile from a medical college in rural setting in the hills of Himachal Pradesh, India

Objective:

The objective of the following study is to assess the clinical profiles and manifestations of snakebite patients in the rural hilly setting of Shivalik and the Lesser Himalayan region of Himachal Pradesh.

Materials and Methods:

A hospital record-based retrospective descriptive study was carried out that included details on demography, clinical profile, treatment and outcome among 200 patients over a period of 2 years. The data was analyzed using Chi-square test for comparison.

Results:

142 (71%) patients were young (age group of 16-45 years) and the number of male patients was 118 (59%) and female patients were 82 (41%). All the cases recorded presented in the months of April to November. Not a single case was recorded from December to March. The most frequently bitten sites were the lower limbs particularly the feet. 86 (43%) of the patients presented without any features of envenomation. Neuroparalysis was the commonest presentation in 53 (46%) patients followed by hemotoxicity in 36 (31%) among symptomatic patients. Early morning neuroparalysis syndrome was the presentation in 26.4% patients. Allergic reactions in the form of early anaphylaxis were noted in 7% patients.

Conclusion:

Snake bite is a neglected tropical disease affecting poor villagers in rural areas. Future research focusing on understanding epidemiological determinants of snake bite is desired.

Dosage comparison of snake anti-venomon coagulopathy

This study was done to determine whether high or low dose ofanti-snake venom (ASV) is better incoagulopathy invictims of envenoming by vipers. This retrospective study was conducted on the 154 patients (Mean age ± SD, Range) of viper snake bites who were referred to the emergency ward of Razi Hospital, Ahvaz, Iran over 2 years period (2004-2006).According to the treatment dosage the patients were divided in two groups include group 1(78 cases), low dose regimen and group 2 (76 cases), high dose one. In group 1, the treatment was performed by administration of 4 to 6 vials of ASV through intravenous infusion.In group 2, the patients were given 5 to 10 vials of ASV as an initial dose. In low dose regimen, the number of received packed red blood cell was higher (14 vs. 3) in comparison with high dose group. The number of ASV vials the patients received was 5.5and 21.06 in group 1 and 2, respectively (5.5±1.7 vs. 21.06±10.89; p < 0.01).The difference in frequency of coagulopathy complications, and need for using packed red blood cell were statistically significant(96.2% and 17.9% in group 1 vs. 34.2% and 3.9% in group 2, p < 0.01).It seems that cautious usage of high dose of ASV (10-20 vials) without very special concerns about the cost, dose, and without hazardous side effects is essential for the routine management of sever snake envenoming.

Neurotoxicity in snakebite--the limits of our knowledge

Snakebite is classified by the WHO as a neglected tropical disease. Envenoming is a significant public health problem in tropical and subtropical regions. Neurotoxicity is a key feature of some envenomings, and there are many unanswered questions regarding this manifestation. Acute neuromuscular weakness with respiratory involvement is the most clinically important neurotoxic effect. Data is limited on the many other acute neurotoxic manifestations, and especially delayed neurotoxicity. Symptom evolution and recovery, patterns of weakness, respiratory involvement, and response to antivenom and acetyl cholinesterase inhibitors are variable, and seem to depend on the snake species, type of neurotoxicity, and geographical variations. Recent data have challenged the traditional concepts of neurotoxicity in snake envenoming, and highlight the rich diversity of snake neurotoxins. A uniform system of classification of the pattern of neuromuscular weakness and models for predicting type of toxicity and development of respiratory weakness are still lacking, and would greatly aid clinical decision making and future research. This review attempts to update the reader on the current state of knowledge regarding this important issue.

Use of antivenoms for the treatment of envenomation by Elapidae snakes in Guinea, Sub-Saharan Africa

Background

In Guinea Elapids are responsible for 20% of envenomations. The associated case fatality rate (CFR) ranged 15-27%, irrespective of treatment.

Results

We studied 77 neurotoxic envenomations divided in 3 groups: a set of patients that received only traditional or symptomatic treatments, and two other groups that received either 2 or 4 initial vials of Antivipmyn® Africa renewed as necessary. CFR was 27.3%, 15.4% and 17.6%, respectively. Although antivenom treatment was likely to reduce CFR, it didn’t seem to have an obvious clinical benefit for the patients, suggesting a low treatment efficacy. Mean delay to treatment or clinical stages were not significantly different between the patients who recovered and the patients who died, or between groups. Interpretation of these results is complicated by the lack of systematic studies under comparable conditions. Of particular importance is the absence of assisted ventilation, available to patients in all the other clinical studies of neurotoxic envenomation.

Conclusion

The apparent lack of clinical benefit may have several causes. The hypothesis of a limited therapeutic window, i.e. an insufficient formation of antigen-antibody complexes once toxins are bound to their targets and/or distributed beyond the reach of antivenom, should be explored.

A randomized multicenter trial of Crotalidae polyvalent immune F(ab) antivenom for the treatment of rattlesnake envenomation in dogs

OBJECTIVE

To determine clinical efficacy of the Crotalidae polyvalent immune F(ab) (ovine) antivenom (OPCA) against progressive crotalid envenomation in the dog as reflected in stabilization or improvement of snakebite severity scores (SSS). Additionally, due to the potential decreased half-life of the F(ab) antibodies in dogs we compared SSS between dogs receiving 2 different dosing regimes.

DESIGN

Prospective, clinical trial.

SETTING

Five veterinary emergency and critical care facilities.

ANIMALS

One hundred and fifteen client-owned Crotalid (rattlesnake) snake bitten dogs in whom worsening of the envenomation syndrome was observed before OPCA treatment.

INTERVENTIONS

In a multicenter randomized clinical trial a single dose (1 vial) of OPCA alone was compared with 2 doses (1/2 vial each) administered 6 hours apart. Standard supportive care was provided in all cases.

MEASUREMENTS AND MAIN RESULTS

Data were available for 115 patients, 9 of which were fatalities. All patients' clinical condition was documented with a standardized SSS system accounting for each major body system. Each fatality received maximum severity scores of 20. The mean severity score of the 115 patients decreased from 4.19 to 3.29 points and there was no difference between the 2 treatment groups. The mean severity score of the 107 patients without fatalities decreased from 4.16 to 2.15. Antivenin-related acute reactions occurred in 6 dogs (6%), and no serum sickness occurred within the 95 cases contacted at the 2-week posttreatment follow-up.

CONCLUSIONS

In the first randomized trial in dogs of antivenin in the United States, OPCA effectively stabilized or terminated venom effects. There were no statistical differences detected between treatment groups within the study time frame.

Pharmacokinetics of a F(ab')2 scorpion antivenom administered intramuscularly in healthy human volunteers

This paper presents the first study of F(ab')(2) scorpion antivenom pharmacokinetics in humans after intramuscular (im) administration. The specific anti-Centruroides scorpion antivenom was used in 6 human healthy volunteers. The fabotherapeutic was administered as a 47.5mg im bolus. Blood samples were drawn at 0, 5, 15, 30, 45, 60 , 90, 120, and 180 min, 6h and at 1, 2, 3, 4, 10 and 21 days after antivenom administration. We measured antivenom concentrations in serum using a specific high sensitivity ELISA method for F(ab')(2). Antivenom concentration in serum was fit to a 3 compartment model (inoculation site, plasma and extra vascular extracellular space), it was assumed that the venom may also be irreversibly removed from plasma. Calculated time course of antivenom content shows that at any time no more that 16.6 (5.3, 31.9)% (median and 95% confidence interval) of the antivenom bolus is present in plasma. The time to peak plasma [F(ab')(2)] was 45 (33, 74) h. The most significant antivenom pharmacokinetic parameters determined were: AUC(im,∞)=803 (605, 1463) mg·h·L(-1); V(c)=8.8 (2.8, 23.6) L; V(ss,im)=55 (47, 64) L; MRT(im)=776(326, 1335) h; CL(t)=3.7 (0.6, 1.9) mL·min(-1); f(im,)V(ss)=0.300 (0.153, 0.466). Comparing these parameters with the ones obtained intravenously by Vázquez et al., the parameters were more disperse between subjects, determined with more uncertainty in each individual subject, and the peak F(ab')(2) in plasma occurred with considerable delay; all indicating that the IM route should not be used to administer the antivenom, with the possible exception of cases occurring very far from hospitals, as an extreme means to provide some protection before the IV route becomes available.

Snake bite in South Asia: a review

Snake bite is one of the most neglected public health issues in poor rural communities living in the tropics. Because of serious misreporting, the true worldwide burden of snake bite is not known. South Asia is the world's most heavily affected region, due to its high population density, widespread agricultural activities, numerous venomous snake species and lack of functional snake bite control programs. Despite increasing knowledge of snake venoms' composition and mode of action, good understanding of clinical features of envenoming and sufficient production of antivenom by Indian manufacturers, snake bite management remains unsatisfactory in this region. Field diagnostic tests for snake species identification do not exist and treatment mainly relies on the administration of antivenoms that do not cover all of the important venomous snakes of the region. Care-givers need better training and supervision, and national guidelines should be fed by evidence-based data generated by well-designed research studies. Poorly informed rural populations often apply inappropriate first-aid measures and vital time is lost before the victim is transported to a treatment centre, where cost of treatment can constitute an additional hurdle. The deficiency of snake bite management in South Asia is multi-causal and requires joint collaborative efforts from researchers, antivenom manufacturers, policy makers, public health authorities and international funders.

Elapid snakebite as a cause of severe hypertension

Snakebite is a common medical emergency in tropical countries, however, autonomic dysfunction is an uncommon manifestation of snakebite. The authors present an unusual manifestation of severe neurotoxic snake envenomation: severe hypertension requiring intravenous antihypertensives. A review of the literature on autonomic dysfunction in neurotoxic snake envenomation is also presented.