Use Of Antivenom Research Articles

A Validation Study of the Limulus Amebocyte Lysate Test as an End-Product Endotoxin Test for Polyvalent Horse Snake Antivenom.

The only definitive management of snake envenoming is the use of snake antivenom. Endotoxin contamination is a serious threat to the safe use of parenteral drugs. A greater understanding of the nature of limulus amebocyte lysate (LAL) test interference and use of permissible dilutions has minimized enhancement problems. Common interference issues include suboptimal pH, enzyme or protein modification, and nonspecific LAL activation. This study aimed at determining the interference factors associated with validating the antivenom sera preparations to avoid false-positive results when testing snake antivenom serum samples by the LAL method. Phase I (preliminary screening/interference assay) was performed to determine a compatible test dilution, which was then used in Phase II (inhibition-enhancement/validation study). The best approach to resolve interference issues was dilution by 1:80 (maximum valid dilution) plus a specific treatment as heat-activation at 70°C-80°C for 10 min with rehydration of LAL reagent with endotoxin-specific buffer solution.LAY ABSTRACT: Snake antivenom sera are produced by immunizing horses with repeated nonlethal doses of snake venom. Bacterial endotoxins constitute one of the major problems in the formulation of pharmaceutical products. One such method for detecting endotoxin levels is the bacterial endotoxin test (BET). However, some substances show strong interfering action with the BET that cannot be avoided by simply diluting the sample solution. In this work, the test for interfering factors was performed as two identical series of product dilutions-one spiked with 2λ and one left unspiked. The result of the interference test revealed the noninterfering dilution (NID) of the product, which was used for the actual validation. Our results showed that after treating the samples using different procedures, such as heat activation at 70-80°C for 10 min followed by centrifugation at 2000 rpm for 10 min and dilution of samples in BD100 (biodispersing agent), inhibition and enhancement up to 1:100 maximum valid dilution (MVD) were observed. Finally, to resolve this inhibition/enhancement problem, the activated sample was heated at 70-80°C for 10 min with rehydration of the Endosafe LAL reagent in an endotoxin-specific buffer solution (BG120) to block β-d-glucans and limulus amebocyte lysate (LAL) reactive material (LAL-RM).

Production of a Human Recombinant Polyclonal Fab Antivenom against Iranian Viper Echis carinatus.

Venomous snakebite is a life-threatening injury in many tropical and subtropical areas including Iran. The gold standard treatment option for human envenomation is the use of antivenoms. Despite the unique effects of horse-derived antivenoms on the treatment of snakebite, they are not fully perfect and need improvements. In this study, human recombinant Fab fragment antivenom was produced in Rosetta-g bacterium using a gene library constructed in the previous study. The prepared Fab was purified in several steps, desalted, and lipopolysaccharide-depleted using ammonium sulfate solution and dialysis against phosphate buffer and Triton X-114 solution, respectively. Subsequently, the product was initially confirmed by the sodium dodecyl sulfate polyacrylamide gel electrophoresis and enzyme-linked immunosorbent assay (ELISA), respectively. Finally, the neutralization potency of the product was investigated in laboratory Syrian Mice. The obtained results showed corresponding reduced bands to Fab fragment with the molecular weight of about 28 kDa at a concentration of 3.1 mg/ml. There was a significant difference between the groups in terms of ELISA test (P<0.05). The neutralization potency of the product against the venom of Echis carinatus (E. carinatus) was about 7 LD50/ml (54.6 µg/ml) when tested on mice. Based on the results, the Fab fragment antivenom had the ability to neutralize the in vivo biological activity of the venom of Iranian E. carinatus. However, further studies are recommended to reach a suitable concentration of antivenom fragment.

Unlocking the secrets of banded coral snake (Calliophis intestinalis, Malaysia): A venom with proteome novelty, low toxicity and distinct antigenicity

The Asiatic coral snakes are basal in the phylogeny of coral snakes. Although envenoming by the Asiatic coral snakes is rarely fatal, little is known about their venom properties and variability from the American coral snakes. Integrating reverse-phase high performance liquid chromatography and nano-liquid chromatography-tandem mass spectrometry, we showed that the venom proteome of the Malaysian banded or striped coral snake (Calliophis intestinalis) was composed of mainly phospholipases A2 (PLA2, 43.4%) and three-finger toxins (3FTx, 20.1%). Within 3FTx, the cytotoxins or cardiotoxins (CTX) dominated while the neurotoxins' content was much lower. Its subproteomic details contrasted with the 3FTx profile of most Micrurus sp., illustrating a unique dichotomy of venom phenotype between the Old and the New World coral snakes. Calliophis intestinalis venom proteome was correlated with measured enzymatic activities, and in vivo it was myotoxic but non-lethal to mice, frogs and geckos at high doses (5–10 μg/g). The venom contains species-specific toxins with distinct sequences and antigenicity, and the antibodies raised against PLA2 and CTX of other elapids showed poor binding toward its venom antigens. The unique venom proteome of C. intestinalis unveiled a repertoire of novel toxins, and the toxicity test supported the need for post-bite monitoring of myotoxic complication. SignificanceMalaysian banded or striped coral snake (Calliophis intestinalis) has a cytotoxin (CTX)-predominating venom proteome, a characteristic shared by its congener, the Malayan blue coral snake (Calliophis bivirgata). With little neurotoxins (NTX), it illustrates a CTX/NTX dichotomy of venom phenotype between the Old World and the New World coral snakes. The low toxicity of the venom imply that C. intestinalis bite envenoming can be managed via symptomatic relief of the mild to moderate pain with appropriate analgesia. Systemically, the serum creatine kinase level of patients should be monitored serially for potential complication of myotoxicity. The distinct antigenicity of the venom proteins implies that the empirical use of heterologous antivenom is mostly inappropriate and not recommended.

Calculation of effective dose fifty (ED50) of antivenom for American pit viper envenomation

The use of conventional approved snake antivenom is the most reliable snake envenomotherapy at the moment. However, because of post-treatment hypersensitivity reactions sometimes caused by large doses of snake antivenoms, the treatment of snake poisoning needs to be reviewed. The effective dose fifty (ED50) of snake antivenom was calculated for 11 American pit viper envenomation as reported by Consroe et al. Four different ED50 formulas were used to determine effective dose fifty of snake antivenom against LD50 of the snake venoms using intravenous route. The findings revealed that snake envenomotherapy is in monotonic dose-response fashion with each formular producing ED50 value for specific snake. The difference in values may be due to species of snakes and the types of ED50 formula used. All the ED50 formulas with the LD50 as numerator yielded higher effective therapeutic dose of snake antivenoms and corresponding higher LD50 values of snake venoms. The lower the denominator, the lower the LD50 and the ED50 value, and the lower the chance of hypersensitivity reaction, but the higher may be the chance of the snake antivenom failure. Therefore, Saganuwan’s formula \( \left({\mathrm{LD}}_{50}=\frac{ED_{50}}{3}\ x\ Wa\ x\ {10}^{-4}\right) \), whereas Wa is weight of animal, could produce effective envenometherapy with low chance of hypersensitivity reactions.

Development of a new approach of immunotherapy against scorpion envenoming: Avian IgYs an alternative to equine IgGs

Antivenom treatment has been largely used against scorpion stings. Despite their efficacy, the use of mammalian antivenoms may cause adverse effects due to the immune system activation. IgYs from hyperimmunized laying hens against venoms could be a promising alternative to equine IgGs due to the various benefits that these antibodies can provide. Here we report the preparation of specific IgYs by immunizing laying hens with Aah (Androctonus australis hector) scorpion venom.IgYs were isolated from egg yolks by water dilution and salt precipitation methods; they were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis, western blot and ELISA. The efficiency of these immunoglobulins on the pathophysiological effects induced by Aah venom was assessed by histological and metabolical analysis of the aorta and the heart. The inflammatory response was assessed by evaluating the granulocyte tissue infiltration and oxidative/nitrosative status.Results revealed high IgYs titers against Aah venom by ELISA. Overall, these IgYs seem to protect efficiently mice against envenomation and neutralized the lethal effects of scorpion venom with a high efficacy; the median effective dose (ED50) was 221 μl/2 LD50; i.e. an amount of 79.23 mg of IgY scan neutralize 1 mg of Aah venom. IgY antibodies neutralize effectively the Aah venom lethality and could prevent severe pathological effects induced by scorpion venom and could be used as an effective alternative to equine IgGs against scorpion envenoming.

Venom proteomics and antivenom neutralization for the Chinese eastern Russell\u2019s viper, Daboia siamensis from Guangxi and Taiwan

The eastern Russell’s viper (Daboia siamensis) causes primarily hemotoxic envenomation. Applying shotgun proteomic approach, the present study unveiled the protein complexity and geographical variation of eastern D. siamensis venoms originated from Guangxi and Taiwan. The snake venoms from the two geographical locales shared comparable expression of major proteins notwithstanding variability in their toxin proteoforms. More than 90% of total venom proteins belong to the toxin families of Kunitz-type serine protease inhibitor, phospholipase A2, C-type lectin/lectin-like protein, serine protease and metalloproteinase. Daboiasiamensis Monovalent Antivenom produced in Taiwan (DsMAV-Taiwan) was immunoreactive toward the Guangxi D. siamensis venom, and effectively neutralized the venom lethality at a potency of 1.41 mg venom per ml antivenom. This was corroborated by the antivenom effective neutralization against the venom procoagulant (ED = 0.044 ± 0.002 µl, 2.03 ± 0.12 mg/ml) and hemorrhagic (ED50 = 0.871 ± 0.159 µl, 7.85 ± 3.70 mg/ml) effects. The hetero-specific Chinese pit viper antivenoms i.e. Deinagkistrodon acutus Monovalent Antivenom and Gloydius brevicaudus Monovalent Antivenom showed negligible immunoreactivity and poor neutralization against the Guangxi D. siamensis venom. The findings suggest the need for improving treatment of D. siamensis envenomation in the region through the production and the use of appropriate antivenom.

Incidence, mechanisms and impact outcome of hyperglycaemia in severe scorpion-envenomed patients.

Hyperglycaemia is often observed in severe scorpion-envenomed patients. It is due to a severe autonomic storm with a massive release of catecholamines, increased glucagon levels, cortisol levels, and either decreased insulin levels or insulin resistance. The presence of hyperglycaemia is an indicator of severity in this specific condition. Indeed, hyperglycaemia was associated with the severity of clinical manifestations of severe scorpion envenomation requiring intensive care unit (ICU) admission. In fact, the presence of hyperglycaemia was associated with the presence of respiratory failure, pulmonary oedema, haemodynamic instability, neurological failure, multisystem organ failure, and an increased mortality and ICU length of stay. As a consequence, we think the presence of hyperglycaemia in scorpion-envenomed patients at the emergency department prompts searching for presence of systemic manifestations or cardiorespiratory manifestations. As a consequence, the presence of hyperglycaemia can help screen severe patients at the emergency department. The current management of severe scorpion envenomation involves the admission and close surveillance in the ICU, where vital signs and continuous monitoring enable early initiation of therapy for life-threatening complications. The use of antivenom for scorpion stings remains controversial. All patients with pulmonary oedema should receive prazosin and possibly dobutamine, according the scorpion's species. Mechanical ventilation is usually used in severe cases. Insulin should be reserved for severe cases with confirmed excessive hyperglycaemia (>10 mmol/l).

Toxin-resolved antivenomics-guided assessment of the immunorecognition landscape of antivenoms

Snakebite envenoming represents a major issue in rural areas of tropical and subtropical regions across sub-Saharan Africa, South to Southeast Asia, Latin America and Oceania. Antivenoms constitute the only scientifically validated therapy for snakebite envenomings, provided they are safe, effective, affordable, accessible and administered appropriately. However, the lack of financial incentives in a technology that has remained relatively unchanged for more than a century, has contributed to some manufacturers leaving the market and others downscaling production or increasing the prices, leading to a decline in the availability and accessibility for these life-saving antidotes to millions of rural poor most at risk from snakebites in low income countries. The shortage of antivenoms can be significantly alleviated by optimizing the use of current antivenoms (through the assessment of their specific and paraspecific efficacy against the different medically relevant homologous and heterologous snake venoms) and by generating novel polyspecific antivenoms exhibiting broad clinical spectrum and wide geographic distribution range. Research on venoms has been continuously enhanced by advances in technology. Particularly, the last decade has witnessed the development of omics strategies for unravelling the toxin composition of venoms (“venomics”) and to assess the immunorecognition profile of antivenoms (“antivenomics”). Here, we review recent developments and reflect on near future innovations that promise to revolutionize the mutually enlightening relationship between evolutionary and translational venomics.

Bitten by A Rattlesnake? Find a Toxicologist!

Approximately 9000 patients are treated for rattlesnake envenomations in the U.S. each year. Treatment typically involves the use of antivenom;

Characterization of the Venom of C. d. cumanesis of Colombia: Proteomic Analysis and Antivenomic Study.

The Colombian rattlesnake Crotalus durissus cumanensis is distributed in three geographic zones of the country: the Atlantic Coast, the upper valley of the Magdalena River, and the eastern plains of the Colombian Orinoquía. Its venom induces neurological symptoms, such as eyelid ptosis, myasthenic facies, and paralysis of the respiratory muscles, which can lead to death. Identification and analysis of C. d. cumanensis showed nine groups of proteins responsible for the neurotoxic effect, of which the crotoxin complex was the most abundant (64.71%). Immunorecognition tests of C. d. cumanensis showed that the use of a commercial antivenom manufactured in Mexico resulted in immunoreactivity.

Antivenom use in bite and sting cases presenting to a public hospital.

To evaluate the distribution of bite and sting cases presenting to a district public hospital and the use of antivenom in scorpion sting and snake bite cases. The demographic characteristics of patients with bites/stings reporting to a public hospital in 2014, the agent involved, the season of reporting, severity of clinical findings during presentation, and use of antivenom in scorpion sting and snake bite cases were evaluated retrospectively. χ2 test was used for statistical analysis. Bite and sting cases comprised 0.5% of all the patients reporting to the hospital's emergency department, with scorpion sting cases comprising almost half (54.2%) of these hospital presentations, followed by Hymenoptera (bee and wasp) sting (30.8%) and snake bite (5.5%) cases. Unnecessary antihistamine administration was found to be significantly high in asymptomatic patients (p=0.00006). Furthermore, antivenom use was found to be significantly high in patients with scorpion sting and snake bite despite the absence of systemic or local indications (p<0.0001, χ2=80.595). The study results showed that antivenom was used in scorpion sting and snake bite cases even when it was not indicated. Therefore, primary practitioners should be provided training for management of envenomation cases and should be made aware of the updated guidelines and references to raise their knowledge levels.

Functional and proteomic comparison of Bothrops jararaca venom from captive specimens and the Brazilian Bothropic Reference Venom

Snake venom is a variable phenotypic trait, whose plasticity and evolution are critical for effective antivenom production. A significant reduction of the number of snake donations to Butantan Institute (São Paulo, Brazil) occurred in recent years, and this fact may impair the production of the Brazilian Bothropic Reference Venom (BBRV). Nevertheless, in the last decades a high number of Bothrops jararaca specimens have been raised in captivity in the Laboratory of Herpetology of Butantan Institute. Considering these facts, we compared the biochemical and biological profiles of B. jararaca venom from captive specimens and BBRV in order to understand the potential effects of snake captivity upon the venom composition. Electrophoretic analysis and proteomic profiling revealed few differences in venom protein bands and some differentially abundant toxins. Comparison of enzymatic activities showed minor differences between the two venoms. Similar cross-reactivity recognition pattern of both venoms by the antibothropic antivenom produced by Butantan Institute was observed. Lethality and neutralization of lethality for B. jararaca venom from captive specimens and BBRV showed similar values. Considering these results we suggest that the inclusion of B. jararaca venom from captive specimens in the composition of BBRV would not interfere with the quality of this reference venom. Biological significanceSnakebite envenomation is a neglected tropical pathology whose treatment is based on the use of specific antivenoms. Bothrops jararaca is responsible for the majority of snakebites in South and Southeastern Brazil. Its venom shows individual, sexual, and ontogenetic variability, however, the effect of animal captivity upon venom composition is unknown. Considering the reduced number of wild-caught snakes donated to Butantan Institute in the last decades, and the increased life expectancy of the snakes raised in captivity in the Laboratory of Herpetology, this work focused on the comparative profiling of B. jararaca venom from captive snakes and the Brazilian Bothropic Reference Venom (BBRV). BBRV is composed of venom obtained upon the first milking of wild-caught B. jararaca specimens, and used to assess the potency of all bothropic antivenoms produced by Brazilian suppliers. The use of proteomic strategies, added to biochemical and neutralization tests, allowed to conclude that, despite some subtle differences detected between these two venoms, venom from captive specimens could be used in the BBRV composition without affecting its quality in antivenom potency assays.

Ulnar artery pseudoaneurysm and compartment syndrome formation after snake bite to the left forearm

Objective: To report the outcome of a patient who developed pseudoaneurysms and compartment syndrome after a Deinagkistrodon acutus snakebite.Case report: A 61-year-old man, bitten by Deinagkistrodon acutus in his left forearm, came to the hospital eight hours after the bite. Despite the use of antivenom and supportive therapy, the patient developed compartment syndrome of the left forearm, the tissue pressure was elevated and fasciotomy was arranged. During the initial surgery, part of the necrotic tissues was removed. Moreover, two pseudoaneurysms of the ulnar artery were identified at the second debridement and the pseudoaneurysms were removed during this surgery. The patient went through a total of four surgeries, recovered and was eventually discharged from the hospital.Conclusion: A snake bite by Deinagkistrodon acutus may be accompanied by pseudoaneurysms and increased intracompartmental pressure.

In Dogs With a European Adder Bite, Does the Use of Antivenom With Supportive Treatment Compared to Supportive Treatment Alone Improve Time to Recovery?

&lt;p&gt;The current literature does not offer convincing evidence for the positive effect of antivenom on time to recovery in dogs envenomated by the European adder. It appears that the use of antivenom in addition to supportive treatment may positively affect local swelling if given within 24 hours of the bite, but the evidence is low quality and further studies are required before a more definitive answer can be reached.&lt;/p&gt;&lt;p&gt;&lt;br /&gt; &lt;img src="https://www.veterinaryevidence.org/rcvskmod/icons/oa-icon.jpg" alt="Open Access" /&gt; &lt;img src="https://www.veterinaryevidence.org/rcvskmod/icons/pr-icon.jpg" alt="Peer Reviewed" /&gt;&lt;/p&gt;

A prospective cohort study of the effectiveness of the primary hospital management of all snakebites in Kurunegala district of Sri Lanka.

IntroductionSri Lanka records substantial numbers of snakebite annually. Primary rural hospitals are important contributors to health care. Health care planning requires a more detailed understanding of snakebite within this part of the health system. This study reports the management and epidemiology of all hospitalised snakebite in the Kurunegala district in Sri Lanka.MethodologyThe district has 44 peripheral/primary hospitals and a tertiary care hospital-Teaching Hospital, Kurunegala (THK). This prospective study was conducted over one year. All hospitals received copies of the current national guidelines on snakebite management. Clinical and demographic details of all snakebite admissions to primary hospitals were recorded by field researchers and validated by comparing with scanned copies of the medical record. Management including hospital transfers was independently assessed against the national guidelines recommendation. Population rates were calculated and compared with estimates derived from recent community based surveys.ResultsThere were 2186 admissions of snakebites and no deaths in primary hospitals. An additional 401 patients from the district were admitted directly to the teaching hospital, 2 deaths were recorded in this group. The population incidence of hospitalized snakebite was 158/100,000 which was significantly lower than community survey estimates of 499/100,000. However there was no significant difference between the incidence of envenomation of 126/100,000 in hospitalised patients and 184/100,000 in the community survey. The utilisation of antivenom was appropriate and consistent with guidelines. Seventy patients received antivenom. Anaphylactic reactions to antivenom occurred in 22 patients, treatment reactions was considered to be outside the guidelines in 5 patients. Transfers from the primary hospital occurred in 399(18%) patients but the majority (341) did not meet the guideline criteria. A snake was identified in 978 cases; venomous snakebites included 823 hump-nosed viper (Hypnalespp), 61 Russell’s viper, 14 cobra, 13 common krait, 03 saw scaled viper.ConclusionsPrimary hospitals received a significant number of snakebites that would be missed in surveys conducted in tertiary hospitals. Adherence to guidelines was good for the use of antivenom but not for hospital transfer or treatment of anaphylaxis. The large difference in snakebite incidence between community and hospital studies could possibly be due to non-envenomed patients not presenting. As the majority of snakebite management occurs in primary hospitals education and clinical support should be focused on that part of the health system.

Shortcomings in snake bite management in rural Cameroon: a case report

BackgroundSnake bites are an important public health problem in developing countries with most bites occurring in rural areas. Severe envenomation often occurs in children and following bites to the face. Prompt administration of potent anti-venom remains the mainstay of management. However in Cameroon, the use of anti-venoms is limited by non-availability, high cost (where available) and poor mastery of treatment guidelines.Case presentationWe present a 10-year-old muslim Cameroonian child from an enclaved rural area, brought to the hospital 12 h after a snake bite to the face, with signs of severe envenomation. Despite the suboptimal anti-venom dose administered to this patient due to a stock out of this medication, supportive therapy was beneficial in ensuring a positive outcome and satisfactory recovery.ConclusionThis highlights snake bites as a public health problem due to the lack of snake anti-venoms in peripheral health facilities, rendering them unable to appropriately manage these cases. National health policies should encourage constant peripheral availability of anti-venoms and the institution of an intervention package for snake bite management, comprising: treatment protocol, staff training, monitoring of compliance and community education to help reduce the mortality and morbidity from snake bites.

Bamboo snake (Trimeresurus Albolabris) Bite in Hong Kong and its Prognostic Factors for Local Complications with Surgical Intervention, Coagulopathy and Thrombocytopenia

Introduction Bamboo snake bite accounts for the majority of venomous snake bites in Hong Kong. The objectives of this study were to evaluate the clinical features and outcomes of Bamboo snake bite in Hong Kong and to identify its prognostic factors for local complications requiring surgical intervention, coagulopathy and thrombocytopenia. Methods It was a retrospective cohort study conducted in a regional hospital of Hong Kong from 1st January 2001 to 31st December 2015. Results Sixty-three subjects were in the final analyses. The mean age was 60 years old. The incidences of swelling, local bruises, blistering, regional lymphadenopathy and local necrosis were 90.5%, 33.3%, 6.3%, 1.6% and 3.2% respectively. The incidences of local complications with surgical intervention, coagulopathy and thrombocytopenia were 6.3%, 13% and 13% respectively. Univariate analysis showed only local necrosis (p=0.003) was significantly associated with local complications with surgical intervention; and only cardiovascular disturbance due to snakebite envenomation (p=0.002) was significantly associated with coagulopathy; and no significantly associated factor was found for thrombocytopenia. There were no case with systemic bleeding and death after Bamboo snake bite. There was no case with allergic reaction after the use of antivenom. Conclusions Local necrosis is significantly associated with surgical intervention. Cardiovascular disturbance is significantly associated with coagulopathy. Allergic reaction after the use of antivenom is rare in Hong Kong.

Bites by the Monocled Cobra, Naja kaouthia, in Chittagong Division, Bangladesh: Epidemiology, Clinical Features of Envenoming and Management of 70 Identified Cases.

We describe 70 cases of monocled cobra (Naja kaouthia) bite admitted to Chittagong Medical College Hospital, Bangladesh. The biting snakes were identified by examining the dead snake and/or detecting N. kaouthia venom antigens in patients' serum. Bites were most common in the early morning and evening during the monsoon (May–July). Ligatures were routinely applied to the bitten limb before admission. Thirty-seven patients consulted traditional healers, most of whom made incisions around the bite site. Fifty-eight patients experienced severe neurotoxicity and most suffered swelling and pain of the bitten limb. The use of an Indian polyvalent antivenom in patients exhibiting severe neurotoxicity resulted in clinical improvement but most patients experienced moderate-to-severe adverse reactions. Antivenom did not influence local blistering and necrosis appearing in 19 patients; 12 required debridement. Edrophonium significantly improved the ability of patients to open the eyes, endurance of upward gaze, and peak expiratory flow rate suggesting that a longer-acting anticholinesterase drug (neostigmine) could be recommended for first aid. The study suggested that regionally appropriate antivenom should be raised against the venoms of the major envenoming species of Bangladesh and highlighted the need to improve the training of staff of local medical centers and to invest in the basic health infrastructure in rural communities.

Cost Minimization Analysis of Different Strategies of Management of Clinically Significant Scorpion Envenomation Among Pediatric Patients.

Scorpion antivenom was recently approved for use in patients with clinically significant scorpion envenomation in the United States; no formal economic analysis on its impact on cost of management has been performed. Three different strategies of management of scorpion envenomation with systemic neurotoxic symptoms in children were compared for cost minimization from a societal perspective. In strategy I, patients were managed with supportive care only without antivenom. In strategy II, an aggressive strategy of full-dose antivenom (initial dose of 3 vials with the use of additional vials administered 1 vial at a time) was considered. In strategy III, a single-vial serial antivenom dosing strategy titrated to clinical response was considered. Clinical probabilities for the different strategies were obtained from retrospective review of medical records of patients with scorpion envenomation over a 10-year period at our institution. Baseline cost values were obtained from patient reimbursement data from our institution. In baseline analysis, strategy I of supportive care only with no antivenom was least costly at US $3466.50/patient. Strategy III of single-vial serial dosing was intermediate but less expensive than strategy II of full-dose antivenom, with an incremental cost of US $3171.08 per patient. In a 1-way sensitivity analysis, at a threshold antivenom cost of US $1577.87, strategy III of single-vial serial dosing became the least costly strategy. For children with scorpion envenomation, use of a management strategy based on serial dosing of antivenom titrated to clinical response is less costly than a strategy of initial use of full-dose antivenom.

Protective Effect of the Sulfated Agaran Isolated from the Red Seaweed Laurencia aldingensis Against Toxic Effects of the Venom of the Snake, Lachesis muta.

Snakebite is a serious occupational hazard affecting mainly rural populations of tropical and subtropical developing countries. Lachesis muta (Bushmaster) bites are extremely serious but are rarely reported in the literature. Bushmaster envenomings are characterized by intense local pain, edema, neurotoxicity, hypotension, local hemorrhage, and dramatic systemic alterations. Antivenom treatment has regularly been used for more than a century; however, it fails to neutralize local tissue damage and hemorrhage, leading to morbidity or disabilities in victims. Thus, the production and clinical use of antivenom must be improved. The present work characterizes, for the first time, a sulfated polysaccharide from the red seaweed, Laurencia aldingensis, including its neutralizing effect on some toxic activities of L. muta venom. Chemical and spectroscopic analyses showed that L. aldingensis produces sulfated agarans with the A-units partially C-2 sulfated or 6-O-methoxylated presetting the B-units in the cyclized (3,6-anhydro-α-L-galactose) or in the non-cyclized form (α-L-galactose). The latter is significantly substituted by sulfate groups on C-6. In vitro and in vivo assays showed that this sulfated agaran inhibited hemolysis, coagulation, proteolysis, edema, and hemorrhage of L. muta venom. Neutralization of hemorrhagic activity was also observed when the agaran was administered by different routes and after or before the venom injection. Furthermore, the agaran blocked the edema caused by a phospholipase A2 isolated from the L. muta venom. Experimental evidence therefore indicates that the sulfated agaran of L. aldingensis has potential to aid antivenom therapy of accidents caused by L. muta venom and may help to develop more effective antivenom treatments of snake bites in general.