Serotherapy in scorpion envenomation: a randomised controlled trial

Production of recombinant scorpion antivenoms in E. coli: current state and perspectives

Scorpion envenomation is a serious health problem in tropical and subtropical zones. The access to scorpion antivenom is sometimes limited in availability and specificity. The classical production process is cumbersome, from the hyper-immunization of the horses to the IgG digestion and purification of the F(ab)'₂ antibody fragments. The production of recombinant antibody fragments in Escherichia coli is a popular trend due to the ability of this microbial host to produce correctly folded proteins. Small recombinant antibody fragments, such as single-chain variable fragments (scFv) and nanobodies (V_HH), have been constructed to recognize and neutralize the neurotoxins responsible for the envenomation symptoms in humans. They are the focus of interest of the most recent studies and are proposed as potentially new generation of pharmaceuticals for their use in immunotherapy against scorpion stings of the Buthidae family. This literature review comprises the current status on the scorpion antivenom market and the analyses of cross-reactivity of commercial scorpion anti-serum against non-specific scorpion venoms. Recent studies on the production of new recombinant scFv and nanobodies will be presented, with a focus on the Androctonus and Centruroides scorpion species. Protein engineering-based technology could be the key to obtaining the next generation of therapeutics capable of neutralizing and cross-reacting against several types of scorpion venoms. KEY POINTS: • Commercial antivenoms consist of predominantly purified equine F(ab)'₂fragments. • Nanobody-based antivenom can neutralize Androctonus venoms and have a low immunogenicity. • Affinity maturation and directed evolution are used to obtain potent scFv families against Centruroides scorpions.

Terrestrial venomous animals, the envenomings they cause, and treatment perspectives in the Middle East and North Africa

The Middle East and Northern Africa, collectively known as the MENA region, are inhabited by a plethora of venomous animals that cause up to 420,000 bites and stings each year. To understand the resultant health burden and the key variables affecting it, this review describes the epidemiology of snake, scorpion, and spider envenomings primarily based on heterogenous hospital data in the MENA region and the pathologies associated with their venoms. In addition, we discuss the venom composition and the key medically relevant toxins of these venomous animals, and, finally, the antivenoms that are currently in use to counteract them. Unlike Asia and sub-Saharan Africa, scorpion stings are significantly more common (approximately 350,000 cases/year) than snakebites (approximately 70,000 cases/year) and present the most significant contributor to the overall health burden of envenomings, with spider bites being negligible. However, this review also indicates that there is a substantial lack of high-quality envenoming data available for the MENA region, rendering many of these estimates speculative. Our understanding of the venoms and the toxins they contain is also incomplete, but already presents clear trends. For instance, the majority of snake venoms contain snake venom metalloproteinases, while sodium channel-binding toxins and potassium channel-binding toxins are the scorpion toxins that cause most health-related challenges. There also currently exist a plethora of antivenoms, yet only few are clinically validated, and their high cost and limited availability present a substantial health challenge. Yet, some of the insights presented in this review might help direct future research and policy efforts toward the appropriate prioritization of efforts and aid the development of future therapeutic solutions, such as next-generation antivenoms.

Neurological and Systemic Manifestations of Severe Scorpion Envenomation

Scorpion envenomation is a life-threatening toxicological emergency and considered as a major public health problem, especially in endemic regions (India, Africa, Latin America); it is generally characterized by low resources and tropical or subtropical weather. Scorpion envenomation is especially fatal in the first hours, usually due to respiratory and/or cardiovascular collapse. The neurologic manifestations, triggered by multiple neurotoxic mechanisms, are varied and complex and mostly reported in children. The aim of this review is to clarify the epidemiologic characteristics and clinical manifestations as well as diagnosis and management of neurologic complications following scorpion envenomation. The management of patients with severe clinical forms is based on early recognition of the sting, antivenom serum administration, and cardiorespiratory and systemic support.

Scorpions and scorpion sting envenoming (scorpionism) in the Arab Countries of the Middle East

The twelve Arab countries of the Middle East are inhabited by 117 species of scorpions of varying medical importance within six families. Scorpion stings are a very common occurrence throughout the region. Twenty-two scorpion species are considered to be dangerously venomous, causing potentially life threatening stings. Accessible literature in English and Arabic on scorpions, scorpion stings and available antivenoms was reviewed to document the scorpion fauna and scorpion stings in each country. Saudi Arabia, Iraq and Jordan report the highest numbers of stings and envenomings. Clinically, the most important toxins in Old World scorpion venoms are α-toxins that target voltage-gated sodium (Na_v) channels at neurotoxin binding site 3, causing sympathetic excitation and the endogenous release of catecholamines that is responsible for transient, but life-threatening myocardial damage. Most victims of scorpion stings suffer severe local pain, but a few, especially children, develop systemic envenoming which, in the case of most Middle Eastern buthid species, such as Androctonus and Leiurus species, is dominated by the cardiovascular and respiratory consequences of hypercatecholinaemic myocarditis. Other syndromes include paralysis (Parabuthus leiosoma), coagulopathy (Nebo hierichonticus and Hemiscorpius species), and local tissue damage, haemolysis and acute kidney injury (H. lepturus). Early antivenom treatment is recommended but its value remains controversial. However, intensive care, with the ancillary use of vasoactive drugs such as prazosin and dobutamine, has proved effective.

Scorpion sting: N-terminal fragment of proB-type natriuretic peptide as an early predictor of pediatric cardiotoxicity

AIM OF THE WORK

This prospective study was conducted to evaluate the clinical reliability of N-terminal fragment of proB-type natriuretic peptide (NT-proBNP) in identifying patients with cardiotoxicity in the early hours following scorpion sting.

SUBJECTS AND METHODS

This study involved 483 children aging between 2-17 years who were admitted to Minia University Poisoning Control Center from 1st January 2010 to 31st December 2019 with a history of scorpion sting, and on clinical evaluation symptoms were manifested. All subjects were clinically examined, investigated for NT-proBNP and CPK-MB on admission, 6 h and 24 h post-envenomation; and subjected to 24 h cardiac monitoring with periodic ECG every 6 h.

RESULTS

Assessment of CPK-MB levels showed a significant increase in all moderate to severe cases 6 h post-envenomation. Assessment of NT-proBNP levels showed a significant increase in all moderate to severe cases on admission and 6 h post-envenomation. Moreover, there was a significant decrease in the NT-proBNP level after 24 h compared with that measured on admission. The sensitivity of NT-proBNP for the diagnosis of myocardial injury at hospital admission was significantly higher than that of CPK-MB.

CONCLUSION

NT-proBNP may be a valuable and sensitive laboratory biomarker to predict cardiotoxicity of scorpion sting in the early hours.

Endangered Saudi Arabian plants having ethnobotanical evidence as antidotes for scorpion envenoming

Scorpion sting envenoming in Saudi Arabia posed major public health problems. Conventional treatment with antivenom with its limitations and hazards called for the use of support remediation like prazosin therapy and phytotherapy as alternative solutions in systematic medicine and a trend of use in medicinal plants. The present study is aiming to procure the medicinal plants that exhibit antidotes of scorpion stings which, were scientifically ignored in Saudi Arabia. Current study data of 11 rare and endangered medicinal plants were collected identified up to the family level, in addition to the parts used. The Family Leguminosae was represented by 4 species. The families Acanthaceae, Amaranthaceae, Annonaceae, Euphorbiaceae, Myrtaceae, Plumbaginaceae, and Zygophyllaceae, were represented with a single species each. All of them have got medicinal ability of antidote potential against scorpion venoms. These commonly used herbs that belonged to 8 families were similar in the use of all parts in treatment. This review study may assist the researchers recruiting new natural herbs and their active products as therapeutic agents against scorpion envenoming. However, these medicinal plants are still requiring pharmacological and phytochemical investigations in order to be claimed as effective antidotes in scorpion envenoming syndrome.

Scorpion envenomation: state of the art

Scorpion envenomation is common in the tropical and subtropical regions. It poses a major public health problem with some patients having serious clinical manifestations and severe complications including death. Old World and New World scorpions are usually contrasted because of differences in venom composition, clinical presentation and severity, and, accordingly, different therapeutic approaches. The majority of scorpion stings are either dry or result in low amounts of injected venom, thus explaining why up to 95% of scorpion stings ensue only in local signs. For a clinical envenomation to occur, it has been suggested that the interaction between the quantity of venom introduced in the body of the prey and the distribution volume should ensue in a critical threshold of scorpion toxin plasma concentration. In this case, there is a massive release of neurohormonal mediators (mainly catecholamine), with systemic vasoconstrictor effects eliciting a sharp increase in systemic arterial pressure and LV-filling pressure and decreased cardiac output. This early phase of cardiac dysfunction, also called "vascular phase", is followed by a severe cardiomyopathy, a form of Takotsubo cardiomyopathy, involving both ventricles and reversible in days to weeks. The more comprehensive understanding of the disease pathophysiology has allowed for a well-codified symptomatic treatment, thus contributing to a substantial reduction in the death toll of scorpion envenomation over the past few decades. The standard intensive-care treatment (when available) overcomes envenomation's consequences such as acute pulmonary edema and cardiogenic shock. Even though it continues to inspire many evaluative studies, immunotherapy seems less attractive because of the major role held by mediators in the pathogenesis of envenomation, and unfavorable pharmacokinetic properties to existing sera compared to venom. Meta-analyses of controlled trials of immunotherapy in severe scorpion envenomation reached similar conclusions: there is an acceptable level of evidence in favor of the use of scorpion antivenom (Fab'₂) against Centruroides sp. in USA/Mexico, while there is still a need for a higher level of evidence for immunotherapy in the Old World envenomation.

A randomized comparative study between intravenous and intramuscular scorpion antivenom regimens in children

BACKGROUND

Scorpion envenomation and its consequences represented a serious healthcare problem in Upper Egypt and considered to be an important cause of life-threatening emergency particularly in children.

METHODS

One hundred patients presented to the emergency department of Assiut University Children Hospital with a history of scorpion sting aged less than 18 years were included in our randomized comparative trial during 2016. Two groups of patients were randomly categorized according to the route of administration of scorpion antivenom; intramuscular and intravenous with 50 patients in each group. Full history, clinical examination, and routine baseline investigations were performed.

RESULTS

Myocarditis, encephalopathy, cardiogenic shock, ICU admission, need for mechanical ventilation, mean hospital stay and mortality were significantly lower in those received intravenous antivenom compared with those received intramuscular one.

CONCLUSION

The results of the present study and other experimental and clinical trials confirmed that the administration of the scorpion antivenom by intravenous route has a lower incidence of systemic toxicity, a better outcome of fatal complication resulted from envenomation especially cardiogenic shock, decreased need for ICU facilities and mechanical ventilation, shorter hospital stay, and better overall outcome than the intramuscular route.

TRIAL REGISTRATION NUMBER

UMIN-CTR Study Design: trial number: UMIN000022032.

Comparing clinical outcomes between two scorpion antivenom dosing strategies in children

Background and Objectives: The clinical course from scorpion envenomation can range from mild to life threatening, particularly in younger children. The F(ab')₂ antivenom currently available in the United States is extremely effective for countering the neurotoxic effects but extremely expensive. This dose comparison study assesses clinical outcomes between two antivenom dosing strategies. Methods: This was a retrospective review of medical records of pediatric patients treated in the pediatric emergency department (PED) with grade 3 or 4 envenomation requiring antivenom. Treatments rendered at two time-periods were assessed: 3-vial first dose (May 2007-August 2011) and single-vial-serial dose (September 2011-June 2016). Primary outcome was the proportion of patients who achieved complete symptom resolution within 4 h post antivenom dose. Results: One hundred and forty-one children met entry criteria, 76 in 3-vial first dose and 65 in single-vial-serial dose. Median age was 4 years (Q1:2-Q3:7), 56.2% males. There were no demographic and differences in clinical severity at presentation between the two dosing groups. All children, irrespective of group assignment, achieved the primary end-point of symptom resolution within 4 h. Median time to complete resolution of symptoms was longer for the single-vial-serial-dosing group vs. the 3-vial-first dose group [90 min (Q1:63-Q3:124) vs. 62 min (Q1:40-Q3:90), p = 0.002]. There were no statistically significant differences between the two groups regarding clinical outcomes including PED discharge, intubation, hospitalization, or death. Conclusion: In this retrospective analysis, children in both single-vial-serial dosing group, and 3-vial-full dosing group, achieved symptom resolution within 4 h of initiating therapy with no additional complications or adverse clinical outcomes.

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).

Saudi medicinal plants for the treatment of scorpion sting envenomation

Scorpion sting envenoming poses major public health problems. The treatment modalities include antivenoms, chemical antidotes and phytotherapy, with varying degrees of effectiveness and side effects. In this investigation, we reviewed the use of Saudi medicinal plants for the treatment of scorpion sting patients. The relevant literature was collected using the online search engines including Science Direct, Google and PubMed with the help of specific keywords. We also used the printed and online resources at our institutional library to gather the relevant information on the use of medicinal plants for the treatment of scorpion sting patients. A descriptive statistics was used for data compilation and presentation. The results of this survey showed the use of at least 92 medicinal plants with beneficial effects for treating victims of stings of different scorpion species. These commonly used herbs spanned to 37 families whilst different parts of these plants were employed therapeutically for alleviation of envenomation symptoms. The application of leaves (41%) was preferred followed by roots (19%), whole plant (14%) and seeds (9%). The use of latex (4%), stem (3%), flowers (3%) and bark (3%) was also reported. In some cases, tannin (2%), rhizome (1%) and shoot (1%) were also used. In conclusion, herbal medicines are effectively used for the treatment of patients with scorpion envenomation. This type of medication is free from side effects as observed with chemical antidotes or antivenom therapy. It is important to identify the active ingredients of herbal drugs for improving their therapeutic potential in traditional medicine.

Clinical and Epidemiological Aspects of Scorpionism in the World: A Systematic Review

OBJECTIVE

Scorpion stings are registered worldwide, but the incidence and the features of the envenomations vary depending on the region. The aim of this review was to summarize the epidemiological, clinical, diagnostic, and therapeutic data worldwide regarding humans stung by scorpions.

METHODS

A systematic review of the literature was conducted through the online databases of the Virtual Health Library (VHL), which hosts Medline and the Latin American and Caribbean Center on Health Sciences Informational (LILACS) database. We selected articles published between January 1, 2002 and July 31, 2014.

RESULTS

Scorpion envenomation reports were found throughout the world, mainly in subtropical and tropical regions. The clinical manifestations were sympathetically and parasympathetically mediated, depending on the species of scorpion. Some of the most common severe complications of scorpionism included respiratory distress syndrome, pulmonary edema, cardiac dysfunction, impaired hemostasis, pancreatitis, and multiple organ failure. Scorpion envenomation could be classified as mild, moderate, and severe, and the therapeutic approach was based on the case severity. The treatment comprised 3 components: symptomatic measures, vital functions support, and injection of antivenom. Moreover, the time that elapsed between the sting and administration of the appropriate medical care was extremely important to the patient's prognosis.

CONCLUSIONS

The large number of scorpion stings worldwide is concerning and reaffirms the need for new prevention measures and policies to reduce the incidence, prevalence, morbidity, and mortality rates from these poisonous arachnids.

Management of scorpion envenoming: a systematic review and meta-analysis of controlled clinical trials

BACKGROUND

Scorpion stings cause an estimated 3000 deaths per annum worldwide. We conducted a systematic review of all controlled clinical trials related to scorpion sting management.

METHODS

We searched PubMed, EMBASE, Scopus, Web of Science and CINAHL and included controlled prospective clinical trials (randomized or non-randomized). The following interventions were assessed: adults and children with scorpion stings treated with (a) steroids vs. placebo, (b) different methods of pain relief, (c) antivenom vs. supportive treatment, (d) prazosin vs. supportive treatment, (e) antivenom vs. prazosin and (f) antivenom plus prazosin vs. prazosin alone. When trials had comparative outcomes, they were combined in a meta-analysis. Data was analysed with Review Manager 5. Dichotomous data were compared with relative risk (RR), and continuous data were compared with mean differences using a fixed effect model. There is no PROSPERO registration number for this study.

RESULTS

Antivenom against Centruroides sp. are effective in reversing the clinical syndrome faster than no antivenom treatment in children (RR, 0.02; 95% CI, 0.01 to 0.06; 322 participants; three trials). Antivenom (against Mesobuthus tamulus) and prazosin combination is better than prazosin alone for faster resolution of symptoms (mean difference, -12.59 h; 95% CI, -14.01 to -11.17; 173 participants; three trials).

CONCLUSIONS

The polyvalent antivenom against Centruroides sp. in USA/Mexico and the monovalent antivenom against M. tamulus in India are effective for rapid resolution of symptoms. Prazosin is useful as an add-on therapy for M. tamulus stings.

Study on Distribution of Scorpions to Provide Prevention and Interventions in Combating Scorpionism in Poldokhtar County, Lorestan Province, Iran

INTRODUCTION

Scorpions are arthropods of medical importance classified in the class Arachnida, inhabiting hot and dry environments. All scorpions have a venomous sting and several thousand people die each year from scorpion stings, but this mortality is due to the venom of about 25 species located in northern Africa, the Middle East, India, Mexico and parts of South America. Poldokhtar County belongs to one of the southern cities of Lorestan Province, providing suitable habitats for many different species of scorpions due to its specific climatic conditions.

AIM

To examine the fauna of scorpion and its distribution in the Poldokhtar County and to provide appropriate preventive and medical interventions in combating scorpionism.

MATERIALS AND METHODS

This present study was a descriptive and analytical cross-sectional study. This study was conducted from April 2014 to November 2014 in regions of Poldokhtar County, Lorestan Province, and west of Iran. Cluster sampling methodology was employed in the sampling and scorpion collection procedure. Sampling was undertaken for an eight-month period, in villages and districts, namely, Myankuhe sharqi, Jayedar, Jelogir and Malavi within the county. The Chi-square test and the Fisher-exact test for homogeneity of proportions were used to compare quantitative variables.

RESULTS

Totally, 393 specimens were captured entailing 193 (49.1%) males and 200 (50.9%) females. There were at least seven species of scorpions belonging to three families; BU= Buthidae, HE = Hemiscorpiidae, SCN = Scorpionidae in Poldokhtar. Out of 393 collected scorpions, seven species, Androctonus crassicauda, Hottentotta (Buthotus) saulcyi, Compsobuthus matthiesseni, Compsobuthus rugosulus, Orthochirus scrobiculosus, Scorpio maurus and Hemiscorpius lepturus were identified. The overall sex ratio of females to males was 1:1.03.

CONCLUSION

It is crucial to improve the knowledge of residents in this region regarding preventive methods towards scorpion stinging. All the known dangerous Iranian scorpions having medical importance, including Hemiscorpius lepturus and Androctonus crassicauda were found in the study area. Additionally, other complementary research detailing the fauna of scorpions and their morphological, ecological and molecular variety in this region is highly recommended to estimate the correlation between particular scorpions' species and ensuring clinical signs and symptoms.

Predictive Factors for Determining the Clinical Severity of Pediatric Scorpion Envenomation Cases in Southeastern Turkey

OBJECTIVE

The aim of this study was to define the epidemiological, clinical, and laboratory manifestations of scorpion envenomation and to identify factors that are predictive of severe cases.

METHODS

The medical files of 41 scorpion envenomation cases were reviewed retrospectively. The cases were classified as mild-moderate or severe. The epidemiological, clinical, and laboratory findings of patients were recorded.

RESULTS

There were 27 patients (65.9%) in the mild-moderate group and 14 patients (34.1%) in the severe group. The median age of all patients was 48 months. The most common systemic finding was cold extremities (41.5%). In all patients, the most commonly observed dysrhythmia was sinus tachycardia (34.1%). Two patients (4.9%) had pulseless ventricular tachycardia and died. Pulmonary edema and myocarditis were observed in 9 patients (22%). Median values of leukocyte and glucose levels were markedly increased in the severe group. Additionally, the mean thrombocyte level (540,857 ± 115,261 cells/mm(3)) in the severe group was significantly increased compared with the mild-moderate group (391,365 ± 150,017 cells/mm(3)). Thrombocyte levels exhibited a positive correlation with leukocyte and glucose values and a negative correlation with patient left ventricular ejection fraction. Multivariate analysis of laboratory parameters indicated that the most predictive factor for clinical severity is thrombocytosis (odds ratio 23.9; 95% CI: 1.6-353.5, P = .021).

CONCLUSIONS

Although our results share some similarities with those of other reports, thrombocytosis was markedly increased in the severe group and served as the most predictive laboratory factor of clinical severity.

Scorpion-related cardiomyopathy: Clinical characteristics, pathophysiology, and treatment

CONTEXT

Scorpion envenomation is a threat to more than 2 billion people worldwide with an annual sting number exceeding one million. Acute heart failure presenting as cardiogenic shock or pulmonary edema, or both is the most severe presentation of scorpion envenomation accounting for 0.27% lethality rate.

OBJECTIVE

The purpose of this review is to characterize the scorpion-related cardiomyopathy, clarify its pathophysiological mechanisms, and describe potentially useful treatments in this particular context.

METHODS

We searched major databases on observational or interventional studies (whether clinical or experimental) on the cardiorespiratory consequences of scorpion envenomation and their treatment. No limit of age or language was imposed. A critical appraisal of the literature was conducted in order to provide a pathophysiological scheme that reconciles reported patterns of cardiovascular toxicity and hypotheses and assumptions made so far.

RESULTS

Early cardiovascular dysfunction is related to the so-called "vascular phase" of scorpion envenomation, which is related to a profound catecholamine-related vasoconstriction leading to a sharp increase in left ventricular (LV) afterload, thereby impeding LV emptying, and increasing LV filling pressure. Following this vascular phase, a myocardial phase occurs, characterized by a striking alteration in LV contractility (myocardial stunning), low cardiac output, and hypotensive state. The right ventricle involvement is symmetric to that of LV with a profound and reversible alteration in right ventricular performance. This phase is unique in that it is reversible spontaneously or under inotropic treatment. Scorpion myocardiopathy combines the features of takotsubo myocardiopathy (or stress myocardiopathy) which is linked to a massive release in catecholamines leading to myocardial ischemia through coronary vasomotor abnormalities (epicardial coronary spasm and/or increase in coronary microvascular resistance). Treatment of pulmonary edema due to scorpion envenomation follows the same principles as those applied for the treatment of cardiogenic pulmonary edema in general: this begins with oxygen supplementation targeting an oxygen saturation of 92% or more, by oxygen mask, continuous positive airway pressure, noninvasive ventilation, or conventional mechanical ventilation. Dobutamine effectively improves hemodynamic parameters and may reduce mortality in severe scorpion envenomation.

CONCLUSION

Scorpion cardiomyopathy is characterized by a marked and reversible alteration in biventricular performance. Supportive treatment relying on ventilatory support and dobutamine infusion is a bridge toward recovery in the majority of patients.

Scorpion sting prevention and treatment in ancient Iran

Due to the medical and therapeutic importance of scorpions in Iranian traditional medicine, this review was conducted on the treatment of scorpion sting as performed by traditional healers in order to realize complications, clinical manifestations, diversities, and deficiencies in the prevention, control, and treatment as mentioned in the pertained literatures. This study tried to make known and investigate attitudes of the Iranian national and traditional medicine towards controlling these venomous animals. Keywords and articles were searched through relevant sites on the Internet. We investigated different journals and references for the Iranian traditional medicine. Based on the articles and books found, we tried to find suitable solutions to problems from the viewpoint of traditional medicine. Scorpion sting dates back to ancient Iran and has been widely reflected in the resources of Iranian traditional medicine. The traditional medicine offers various guidelines that can be beneficial in this respect. New attitude towards scorpion sting with regard to traditional medicine resources can enhance control and prevention of scorpion stings. Consequently, this attitude leads authorities and researchers to a decreased level of scorpion stings or related consequences.

A randomized trial comparing intravenous paracetamol, topical lidocaine, and ice application for treatment of pain associated with scorpion stings

OBJECTIVE

Appropriate treatment for scorpion-associated pain was not previously studied in detail in the literature. The aim of this study was to compare the efficacy of three treatment modalities in patients with painful scorpion stings using visual analog scale (VAS) scores.

MATERIALS AND METHODS

A randomized study was carried out during a 1-year period in patients with scorpion stings who did not have any systemic signs or symptoms. Patients were treated with intravenous paracetamol, topical lidocaine, or ice application. Pain intensity was evaluated using VAS score at the time of presentation to emergency department and at 30th, 60th, 120th, and 240th minutes. Changes in VAS scores from baseline were recorded.

RESULTS

A total of 130 patients were included in the statistical analysis. Significant reduction in pain intensity was observed with topical lidocaine group when compared with the ice application group (p < 0.001) and paracetamol group (p < 0.001) in all selected time intervals. The median reduction in scores at 30 min after therapeutic intervention was 25.0 mm for topical lidocaine, 14.5 mm for ice application, and 10.0 mm for intravenous paracetamol. No adverse events were reported.

DISCUSSION

Our results revealed that topical lidocaine is superior to both intravenous paracetamol and local ice application and its effect lasts several hours after envenomation.

CONCLUSION

Topical lidocaine is an effective and safe treatment in scorpion sting associated with pain in patients with nonsystemic signs and symptoms.

Neuropeptide Y family-degrading metallopeptidases in the Tityus serrulatus venom partially blocked by commercial antivenoms

Accidents caused by scorpions represent a relevant public health issue in Brazil, being more recurring than incidents with snakes and spiders. The main species responsible for this situation is the yellow scorpion, Tityus serrulatus, due especially to the great frequency with which accidents occur and the potential of its venom to induce severe clinical manifestations, even death, mainly among children. Although neurotoxins are well characterized, little information is known about other components of scorpion venoms, such as peptidases, and their effect on envenomation. Previous results from our group showed that the metallopeptidases present in this venom are capable of hydrolyzing the neuropeptide dynorphin 1-13 in vitro, releasing Leu-enkephalin, which may interact with ion channels and promote indirect neurotoxicity. Thus, this study aims to get more information about the effect of toxic peptidase activity present in the venom on biologically active peptides, and to evaluate the in vitro neutralizing potential of commercial antivenoms produced by the Butantan Institute. A set of human bioactive peptides were studied as substrates for the peptidases, and the members of the neuropeptide Y family were found to be the most susceptible ones. All new substrate hydrolyses were totally inhibited by ethylenediaminetetracetic and not blocked by phenylmethanesulfonylfluoride, indicating that metallopeptidases were responsible for the peptidase activity. Also, peptidase activities were only partially inhibited by therapeutic Brazilian scorpion antivenom (SAV) and arachnid antivenom (AAV). The dose-response inhibition by both antivenoms indicates that AAV neutralizes better than SAV at the used doses. These characterizations, unpublished until now, can contribute to the improvement of our knowledge about the venom and envenomation processes by T. serrulatus.

Clinical characteristics and outcome of children stung by scorpion

Scorpion envenomation is a health problem in children in tropical and subtropical regions. The aim of this study was to evaluate demographic and clinical characteristics as well as outcomes in referred children to Assiut University Children Hospital during the year 2012 with a history of scorpion sting. The medical files of these patients were reviewed retrospectively for demographic data, time and site of biting, and clinical manifestations. Laboratory investigations of the patients were reviewed for complete blood count (CBC), liver function tests, creatinine phosphokinase (CPK), lactate dehydrogenase (LDH), arterial blood gases, and serum electrolytes. Results showed 111 children with a history of scorpion sting; 69 males and 42 females with a median age of 5 years. Out of the studied patients, 53.2 % were classified as class III of clinical severity with recorded pulmonary edema in 33.3 %, cardiogenic shock in 46.8 %, and severe neurological manifestations in 22.8 %. Twelve patients (10.8 %) were classified as class II with mild systemic manifestations, and 36 % of the patients were classified as class I with only local reaction. Outcomes of these patients were discharge without sequelae in 55.8 %, discharge with sequelae in 26.1 %, and death in 18.1 %.

CONCLUSION

more than half of stung children had a severe clinical presentation and about one fifth died. Aggressive treatment regimens are recommended for such patients to improve the outcome.

Efficacy of scorpion antivenom plus prazosin versus prazosin alone for Mesobuthus tamulus scorpion sting envenomation in children: a randomised controlled trial

OBJECTIVE

To assess the efficacy of combined use of scorpion antivenom (SAV) with prazosin, compared with prazosin alone in children with Mesobuthus tamulus scorpion envenomation.

STUDY DESIGN

Randomised controlled trial.

SETTING

A tertiary care hospital in south India.

PATIENTS

50 children with definite history and/or systemic manifestations of scorpion envenomation were recruited from the paediatric emergency or outpatient department from February 2012 to July 2013.

INTERVENTIONS

The children were randomised into two groups. In 25 children, SAV was administrated as a slow intravenous bolus combined with prazosin (group A). Others received prazosin alone (group B). Results were analysed by Student t test and χ(2) test.

MAIN OUTCOME MEASURES

Time required for resolution of autonomic symptoms, total dose of prazosin, adverse events.

RESULTS

Children in group A recovered earlier than those in group B (mean difference 9.1 h, 95% CI 6.0 to 12.2). 23 children (92%) in group A were clear of autonomic symptoms within 10 h, compared with 10 children (40%) in group B (mean difference 52%, 95% CI 29% to 75%). The proportion of children deteriorating to clinical grade 3 or 4 was 8% in group A as against 44% in group B (p<0.01). The mean dose of prazosin required was 54 µg/kg versus 130.8 µg/kg in group A and B, respectively (p<0.01). SAV was not associated with severe adverse reactions.

CONCLUSIONS

Usage of SAV led to faster recovery and reduced the incidence of myocardial dysfunction. Combined therapy with SAV and prazosin is beneficial for children with M tamulus scorpion envenomation.

TRIAL REGISTRATION NUMBER

CTRI/2013/09/004002 (Clinical Trials Registry of India).

Effectiveness of anti scorpion venom for red scorpion envenomation

OBJECTIVE

To study the efficacy of anti-scorpion venom plus prazocin.

METHODS

Comparison of clinical features, outcome and duration of stay between children receiving anti-scorpion venom plus prazocin or prazocin alone for management of red scorpion envenomation.

RESULTS

Requirement for dopamine and requirement and duration of dobutamine therapy were significantly less in patients received anti-venom plus prazocin than those had prazocin only. Faster recovery was seen in cases who received anti-scorpion venom plus prazocin than prazocin only group.

CONCLUSIONS

Anti-scorpion venom plus prazosin was safe and more effective than prazocin alone for scorpion envenomation.

Scorpion anti-venom activity of botanicals: a pharmacological approach

Scorpion bite is considered as one of the common and dangerous phenomenon throughout the world. The clinical manifestations include pulmonary edema, myocardial damage, intracerebral haemorrhage, brachial plexopathy, renal failure etc. which sometimes leads to mortality. The common antivenin therapy includes anti-scorpion venom serum or prazosin. In the vast rural areas of the third world countries phytotherapy is considered as an alternative system of medicine and scorpion sting is treated with the help of medicinal botanicals. As the safety and efficacy are considered as important aspects of anti venin therapy, conventional treatment can be supported by the herbal remedy. The present review compiles a number of medicinal plants pharmacologically evaluated in vitro and/or in vivo for scorpion antivenin properties. Considering the aspects like cost effectiveness, availability, lesser side effects and development of drug resistance, plant based anti venin therapy may be considered as a possible remedy against scorpion envenomation.

Molecular cloning and biochemical characterization of the first Na(+)-channel α-type toxin peptide (Acra4) from Androctonus crassicauda scorpion venom

Due to the medical importance played in Turkey by stings of the scorpion Androctonus crassicauda, its venom has been studied with more attention. In this communication we report a new toxic peptide, named Acra4, because it is the fourth peptide completely characterized from venom of this scorpion. The peptide contains 64 amino acid residues stabilized by four disulfide bridges, with a molecular weight of 6937 Da. Purification of the lethal peptide was performed by three steps of high performance liquid chromatography (HPLC) separations, and the molecular weight was determined by mass spectrometry analysis and the full amino acid sequence was obtained by direct Edman degradation in conjunction with gene cloning. The LD50 of Acra4 was 50.5 ng/20 g mouse body weight (95% confidence intervals from 48.8 to 52.2 ng/20 g mouse body weight). Additionally, from a sample of cDNA of A. crassicauda four genes were cloned displaying sequence similarities to known scorpion toxins, and are reported here as potentially toxic peptides, named Acra5 to Acra8. Electrophysiological studies of Acra4 were performed using Na(+)-channels expressed in F11 cell culture, by patch-clamp recordings. This is the first time that such peptide from A. crassicauda having a specific Na(+)-channel α-type effect is reported. Its affinity toward Na(+)-channels in F11 cell line is in the order of 1 μM concentration.

Emerging options for the management of scorpion stings

Scorpion stings are common in many tropical countries. Although most scorpion stings cause only localized pain without life-threatening envenoming, about one third of stings cause systemic envenoming which can result in death. Children are particularly sensitive to scorpion envenoming. The severity of scorpion stings is related to the presence of neurotoxins in the venom that cause a sudden release of neurotransmitters from the autonomic nervous system, predominantly sympathetic. There is also a strong inflammatory response that worsens symptoms, including those of a respiratory nature. Several vital functions may be directly affected, including the cardiovascular, respiratory, and neuromuscular systems. Hypertension is constant at the beginning of systemic envenoming and sometimes has a severe cardiac and respiratory impact. Although controversial, immunotherapy is the only etiological treatment. Administered early, it prevents many complications and improves the outcome. New antivenoms are highly purified immunoglobulin fragments, the efficacy and safety of which are excellent. As a consequence, adverse reactions to antivenoms are now very rare and usually mild, which should limit any reluctance regarding their routine use. Symptomatic treatment is still necessary to support immunotherapy, especially in cases of delayed arrival at hospital. A combination of both approaches should be considered, based on local resources and constraints.

Diabody mixture providing full protection against experimental scorpion envenoming with crude Androctonus australis venom

Androctonus australis is primarily involved in envenomations in North Africa, notably in Tunisia and Algeria, and constitutes a significant public health problem in this region. The toxicity of the venom is mainly due to various neurotoxins that belong to two distinct structural and immunological groups, group I (the AahI and AahIII toxins) and group II (AahII). Here, we report the use of a diabody mixture in which the molar ratio matches the characteristics of toxins and polymorphism of the venom. The mixture consists of the Db9C2 diabody (anti-group I) and the Db4C1op diabody (anti-AahII), the latter being modified to facilitate in vitro production and purification. The effectiveness of the antivenom was tested in vivo under conditions simulating scorpion envenomation. The intraperitoneal injection of 30 μg of the diabody mixture protected almost all the mice exposed to 3 LD(50) s.c. of venom. We also show that the presence of both diabodies is necessary for the animals to survive. Our results are the first demonstration of the strong protective power of small quantities of antivenom used in the context of severe envenomation with crude venom.

Amelioration of cardio-respiratory perturbations following Mesobuthus eupeus envenomation in anesthetized rabbits with commercial polyvalent F(ab')2 antivenom

Immunotherapy is the only specific treatment for scorpion sting. In the present study, protective effects of polyvalent antivenom against hemodynamic disturbances, biomarkers (troponin T, creatinine kinase isoenzyme MB, Lactate dehydrogenase) changes, electrocardiogram abnormalities and histopathological complications in heart and lung induced by Mesobuthus eupeus scorpion venom was investigated in anesthetized rabbits. Twenty four rabbits were randomized into four equal groups: six rabbits in control group received 1 ml ultra-pure water subcutaneously (group 1). Group two received LD50 of venom (4.5 mg/kg). In the third and fourth groups, 5 ml of scorpion antivenom was administrated intravenously simultaneous with venom injection and 60 min following envenomation, respectively. Results of the present study indicate significant decrease in hemodynamic parameters following envenomation in the second group of animals. Venom injection caused edema, myocytolysis, coagulation necrosis, hemorrhage in heart as well as edema, hemorrhage and vascular thrombus in lungs. Although envenomed rabbits presented rises in LDH and TnT but no alteration in CK-MB was observed. Electrocardiogram monitoring of rabbits showed ST elevation and inverted T waves. Simultaneous administration of antivenom and venom prevented entirely the clinical signs, hemodynamic disturbances, markers changes, ECG abnormalities and histopathological damages. Delayed immunotherapy gradually ameliorated clinical signs, hemodynamic disturbances and markers changes related to envenomation. Histopathological evaluation showed slight alterations such as mild myocytolysis in heart and mild edema in lung following delayed immunotherapy. In conclusion, scorpion antivenom administration has preventive, neutralizing and curative properties for M. eupeus scorpion envenomation, if it would be applied at optimum time, dose and route.

Scorpion envenomation and antivenom therapy

Scorpion envenomation is a dangerous and common global event that can result in a variety of toxic clinical effects. These are typically managed with supportive care or antivenom. Antivenom use is controversial because of conflicting evidence of effectiveness for adrenergic toxicity. However, both controlled and uncontrolled studies have shown that antivenom is effective in resolving neuromotor toxicity associated with envenomations by the scorpions of genus Centruroides.

Efficacy and safety of scorpion antivenom plus prazosin compared with prazosin alone for venomous scorpion (Mesobuthus tamulus) sting: randomised open label clinical trial

OBJECTIVE

Envenomation by Mesobuthus tamulus scorpion sting can result in serious cardiovascular effects. Scorpion antivenom is a specific treatment for scorpion sting. Evidence for the benefit of scorpion antivenom and its efficacy compared with that of commonly used vasodilators, such as prazosin, is scarce. We assessed the efficacy of prazosin combined with scorpion antivenom, compared with prazosin alone, in individuals with autonomic storm caused by scorpion sting.

DESIGN

Prospective, open label randomised controlled trial.

SETTING

General hospital inpatients (Bawaskar Hospital and Research Centre Mahad Dist-Raigad Maharashtra, India).

PARTICIPANTS

Seventy patients with grade 2 scorpion envenomation, older than six months, with no cardiorespiratory or central nervous system abnormalities.

INTERVENTION

Scorpion antivenom plus prazosin (n=35) or prazosin alone (n=35) assigned by block randomisation. Treatment was not masked. Analysis was by intention to treat.

MAIN OUTCOME MEASURES

The primary end point was the proportion of patients achieving resolution of the clinical syndrome (sweating, salivation, cool extremities, priapism, hypertension or hypotension, tachycardia) 10 hours after administration of study drugs. Secondary end points were time required for complete resolution of clinical syndrome, prevention of deterioration to higher grade, doses of prazosin required overall and within 10 hours, and adverse events. The study protocol was approved by the independent ethics committee of Mumbai.

RESULTS

Mean (SD) recovery times in hours for the prazosin plus scorpion antivenom group compared with the prazosin alone groups were: sweating 3 (1.1) v 6.6 (2.6); salivation 1.9 (0.9) v 3 (1.9); priapism 4.7 (1.5) v 9.4 (1.5). Mean (SD) doses of prazosin in the groups were 2 (2.3) and 4 (3.5), respectively. 32 patients (91.4%, 95% confidence interval 76.9% to 97.8%) in the prazosin plus antivenom group showed complete resolution of the clinical syndrome within 10 hours of administration of treatment compared with eight patients in the prazosin group (22.9%, 11.8% to 39.3%). Patients from the antivenom plus prazosin group recovered earlier (mean 8 hours, 95% CI 6.5 to 9.5) than those in the control group (17.7 hours, 15.4 to 19.9; mean difference -9.7 hours, -6.9 to -12.4). The number of patients whose condition deteriorated to a higher grade was similar in both groups (antivenom plus prazosin four of 35, prazosin alone five of 35). Hypotension was reported in fewer patients in the antivenom plus prazosin group (12 of 35, 34.3%) than in the prazosin group (19 of 35, 54.3%), but the difference was not statistically significant. No difference was noted in change in blood pressure and pulse rate over time between two groups.

CONCLUSION

Recovery from scorpion sting is hastened by simultaneous administration of scorpion antivenom plus prazosin compared with prazosin alone.

TRIAL REGISTRATION NUMBER

CTRI/2010/091/000584 (Clinical Trials Registry India).

Scorpion envenomation among children: clinical manifestations and outcome (analysis of 685 cases)

Our objective was to characterize both epidemiologically and clinically manifestations after severe scorpion envenomation and to define simple factors indicative of poor prognosis in children. We performed a retrospective study over 13 years (1990-2002) in the medical intensive care unit (ICU) of a university hospital (Sfax-Tunisia). The diagnosis of scorpion envenomation was based on a history of scorpion sting. The medical records of 685 children aged less than 16 years who were admitted for a scorpion sting were analyzed. There were 558 patients (81.5%) in the grade III group (with cardiogenic shock and/or pulmonary edema or severe neurological manifestation [coma and/or convulsion]) and 127 patients (18.5%) in the grade II group (with systemic manifestations). In this study, 434 patients (63.4%) had a pulmonary edema, and 80 patients had a cardiogenic shock; neurological manifestations were observed in 580 patients (84.7%), 555 patients (81%) developed systemic inflammatory response syndrome (SIRS), and 552 patients (80.6%) developed multi-organ failure. By the end of the stay in the ICU, evolution was marked by the death in 61 patients (8.9%). A multivariate analysis found the following factors to be correlated with a poor outcome: coma with Glasgow coma score ≤ 8/15 (odds ratio [OR] = 1.3), pulmonary edema (OR = 2.3), and cardiogenic shock (OR = 1.7). In addition, a significant association was found between the development of SIRS and heart failure. Moreover, a temperature > 39°C was associated with the presence of pulmonary edema, with a sensitivity at 20.6%, a specificity at 94.4%, and a positive predictive value at 91.7%. Finally, blood sugar levels above 15 mmol/L were significantly associated with a heart failure. In children admitted for severe scorpion envenomation, coma with Glasgow coma score ≤ 8/15, pulmonary edema, and cardiogenic shock were associated with a poor outcome. The presence of SIRS, a temperature > 39°C, and blood sugar levels above 15 mmol/L were associated with heart failure.

Scorpion stings in Turkey: epidemiological and clinical aspects between the years 1995 and 2004

The most important health-threatening scorpions found in Turkey are; Androctonus crassicauda, Leiurus quinquestriatus, Mesobuthus gibbosus and M. eupeus species, all of which belong to the Buthidae family. The epidemiological and clinical findings of scorpion stings in Turkey were evaluated between the years 1995 and 2004 based on data recorded in the National Poison Information Center (NPIC). A total of 930 cases were recorded. The cases mostly occurred in the month of July. The gender distribution was 50.22% female and 45.48% male. It was shown that the 20-29 age group presented more scorpion stings. Most of the stings occurred in Central Anatolia and Marmara regions of Turkey. Patients at the hospital showed signs of localized (pain, hyperemia, edema and numbness) and systemic effects (hyperthermia, nausea and vomiting, tachycardia, shivering and lethargy) but no lethality was notified. According to records, 33% of the poisoned patients were treated with antivenin in healthcare facilities.

[Emergency immunotherapy: snake and scorpion antivenoms]

Passive immunotherapy was discovered in 1894. It is the only etiological treatment of envenomations by snakes or scorpions. Immunotherapy is based on administration of antibodies produced by an animal hyperimmunised against venom. Improvement of whole antivenomous sera was obtained, first by separating the antibodies from other components of blood plasma, then by using enzyme digestion of immunoglobulins G and, finally, by purifying the final product. Efficacy and also tolerance were significantly increased. Antivenom administration should be performed through the intravascular route to ensure better diffusion and to facilitate the complexion with the venom. The sale of antivenoms, in particular in Africa, is considerably reduced since about thirty years and is not in adequacy with the epidemiologic needs. In addition to the high cost of the current products, the difficulties of supplying, storage and use seem at the origin of this rejection by both the health staff and the victims who resort massively to traditional medicine. Whereas WHO reminds the rules of production and use of the antivenoms to producers and authorities in charge of drug regulations, it appears that the accessibility of the antivenoms depends on a concerted effort from all the actors, coordinated by health authorities: producers, distributers, manufacturers and public. Beyond technological improvements necessary in antivenom production, the strategy to be implemented must include the strict evaluation of the needs based on epidemiologic studies, the share of cost recovery between all the actors, and the optimization of the therapeutic protocol to make it applicable in remote health centres. Once confidence towards immunotherapy will be restored, mortality will be significantly reduced.

Identification of potent nanobodies to neutralize the most poisonous polypeptide from scorpion venom

Scorpion venom, containing highly toxic, small polypeptides that diffuse rapidly within the patient, causes serious medical problems. Nanobodies, single-domain antigen-binding fragments derived from dromedary heavy-chain antibodies, have a size that closely matches that of scorpion toxins. Therefore these nanobodies might be developed into potent immunotherapeutics to treat scorpion envenoming. Multiple nanobodies of sub-nanomolar affinity to AahII, the most toxic polypeptide within the Androctonus australis hector venom, were isolated from a dromedary immunized with AahII. These nanobodies neutralize the lethal effect of AahII to various extents without clear correlation with the kinetic rate constants kon or koff, or the equilibrium dissociation constant, KD. One particular nanobody, referred to as NbAahII10, which targets a unique epitope on AahII, neutralizes 7 LD50 of this toxin in mice, corresponding to a neutralizing capacity of approx. 37000 LD50 of AahII/mg of nanobody. Such high neutralizing potency has never been reached before by any other monoclonal antibody fragment.

Severe scorpion envenomation in children: Management in pediatric intensive care unit

BACKGROUND

Scorpion envenomation is a common public health problem worldwide and children are at greater risk of developing severe cardiac, respiratory and neurological complications. The aim of this study was to evaluate the effects of antivenin and/or prazosin use on prognosis of scorpion-envenomed children admitted to pediatric intensive care unit (PICU).

METHODS

The standardized medical records of 45 children hospitalized with severe scorpion sting in PICU were retrospectively evaluated. General characteristics of the children, clinical and laboratory findings, treatment approaches and prognosis were evaluated.

RESULTS

The mean age of the patients were 6.1 +/- 4.1 years ranging between 4 month and 15 years. Male to female ratio was 1.8. Thirty-three (71.1%) cases of scorpion stings came from rural areas. Twenty-six (57.8%) of the patients were stung by Androctonus crassicauda. The most common sting localization was the foot-leg (55.6%). The mean duration from the scorpion sting to hospital admission was 4.5 +/- 2.6 hours. The most common findings at presentation were cold extremities (95.5%), excessive sweating (91.1%) and tachycardia (77.7%). The mean leukocyte count, and serum levels of glucose, lactate dehydrogenase, creatine phosphokinase and international normalized ratio were found above the normal ranges. Prazosin was used in all patients, dopamine in 11 (24.4%) and Na-nitroprusside in 4 (8.8%) patients. Two children died (4.4%) due to pulmonary oedema. These children, in poor clinical status at hospital admission, needed mechanical ventilation, and death occurred despite use of antivenin and prazosin in both of them.

CONCLUSION

The current management of children with severe scorpion envenomation consists of administration of specific antivenom and close surveillance in a PICU, where vital signs and continuous monitoring enable early initiation of therapy for life-threatening complications. The aggressive medical management directed at the organ system specifically can be effective. Our data indicated that when admission to hospital is late, the beneficial effect of antivenom and/or prazosin is questionable in severe scorpion stings.