Incidence of immediate and delayed hypersensitivity to Centruroides antivenom

Scorpion Stings and Antivenom Use in Arizona

BACKGROUND

Arizona's rugged desert landscape harbors many venomous animals, including a small nocturnal scorpion, Centruroides sculpturatus, whose venom can cause severe neuromotor disturbance. An effective antivenom is available at selected health care facilities in the state.

METHODS

We analyzed 4398 calls of scorpion stings to the Arizona Poison and Drug Information Center (APDIC) in Tucson over a period of 3 years, from January 2017 to December 2019.

RESULTS

We followed 1952 (44.4%) of the victims to resolution. We excluded 2253 callers with minimal effects of the sting and 193 victims with possible toxic effects who were lost to follow-up. The most common complaints among callers were pain at the sting site in 88.9% and local numbness in 62.2%. Detailed clinical information was obtained from 593 calls from a health care facility. Neuromotor signs consistent with C. sculpuratus envenomation included nystagmus in 163 (27.5%), hypersalivation in 91 (15.3%), and fasciculations in 88 (14.8%). Antivenom (Anascorp; Rare Disease Therapeutics, Inc., Franklin, Tenn) was administered to 145 patients. Most were children <5 years old (n = 76, or 54.4%); 27 (18.6%) were 5-9 years old and 42 (30.0%) were ≥10 years of age. About half, 79 of 145 (54.5%) victims who received antivenom, met the APDIC recommended use criteria.

CONCLUSIONS

Patients treated with antivenom exhibited a rapid resolution of symptoms without immediate or delayed hypersensitivity reactions. We recommend broadened availability of antivenom at sites where it is most needed.

Centruroides sculpturatus envenomation in three adult patients requiring treatment with antivenom

CONTEXT

Envenomation by Centruroides sculpturatus can manifest with cranial nerve dysfunction and neuromuscular hyperactivity. While these symptoms are most commonly seen in young children, they may also be seen in adults.

CASE DETAILS

Three cases of adult patients are presented with grades III & IV scorpion envenomation. They reported symptoms including disconjugate, roving eye movements, and motor involvement. Also reported were hyposmia, difficulty with fine motor movements, and dysgeusia. All were first treated with benzodiazepines with little to no effect. They then received a three vial antivenom bolus with resolution of severe symptoms within 30-60 min.

DISCUSSION

Severe Centruroides envenomation can occur in adults as well as children. These three cases demonstrate the usefulness, safety, and effectiveness of antivenom therapy to quickly relieve symptoms in adult patients with grades III & IV envenomations.

Evolution of alternative methodologies of scorpion antivenoms production

Scorpionism represents a serious public health problem resulting in the death of children and debilitated individuals. Scorpion sting treatment employs various strategies including the use of specific medicines such as antiserum, especially for patients with severe symptoms. In 1909 Charles Todd described the production of an antiserum against the venom of the scorpion Buthus quinquestriatus. Based on Todd's work, researchers worldwide began producing antiserum using the same approach i.e., immunization of horses with crude venom as antigen. Despite achieving satisfactory results using this approach, researchers in this field have developed alternative approaches for the production of scorpion antivenom serum. In this review, we describe the work published by experts in toxinology to the development of scorpion venom antiserum. Methods and results describing the use of specific antigens, detoxified venom or toxins, purified toxins and or venom fractions, native toxoids, recombinant toxins, synthetic peptides, monoclonal and recombinant antibodies, and alternative animal models are presented.

Safety of intravenous equine F(ab')2: insights following clinical trials involving 1534 recipients of scorpion antivenom

INTRODUCTION

The technology of antivenom production has gradually changed since the earliest production of antisera around the turn of the 20th century. Use of early antisera was associated with frequent acute adverse reactions and serum sickness. New F(ab')2 products, manufactured using pepsin degradation of immunoglobulin together with precipitation of unwanted protein and albumin serum fractions, should in concept cause fewer immune reactions in clinical use.

METHODS

A linked set of five prospective clinical trials of an equine F(ab')2 antivenom, together with one historical control study, were completed during development of the product for a Biological License Application through the US FDA. Adverse events were recorded and categorized, with particular attention to the frequency of immune reactions.

RESULTS

A total of 1534 patients ages 0.1-90.5 years received antivenom, in Arizona and in Mexico, for treatment of scorpion envenomation. Total dosing ranged from 1 to 5 vials except for one outlier who received 10 vials. Estimated protein exposure was 12-275 mg per patient (outlier, up to 550 mg). Three patients (0.2%) had acute reactions to antivenom infusion (one urticaria, one urticaria and dyspnea, and one panic attack). Eight (0.5%) had rashes suggestive of Type 3 immune reactions, although none had the full syndrome of serum sickness. Two women were treated for envenomation during the first trimester of pregnancy, one of whom subsequently experienced a spontaneous abortion.

CONCLUSIONS

Rates of immune reaction to this product were two orders of magnitude lower than the range (up to 75% for early and 81% for late reactions) historically reported with use of minimally refined whole immunoglobulin products against a variety of infections and envenomations. Lower protein dose, greater purity of the active component, lack of the immunogenic Fc portion of the immunoglobulin molecule, and slow intravenous infusion are likely to be the reason for this. Clinical implications of a safer product include that it can be employed in settings where antivenom was once considered too dangerous to use, such as primary care clinics and remote rural areas.

Clinical course of bark scorpion envenomation managed without antivenom

Bark scorpion envenomation is potentially life threatening in children and traditionally treated with antivenom (AV). We sought to describe the clinical course, management, complications and outcome of children with severe scorpion envenomation treated with supportive care during a period when AV was unavailable. A retrospective chart review was performed, all children presenting to a referral hospital between September 1, 2004 and July 31, 2006 with severe scorpion envenomation not receiving AV, were included. A standardized data abstraction form was used to record time of symptom onset, time to healthcare facility (HCF), clinical findings, treatment, complications, and length of stay. Eighty-eight patients were included with mean age of 3.7 years (0.33-12). Mean time to symptom onset was 20 min (0-130) and mean time to HCF was 79 min (10-240). Incidence of clinical manifestations include: neuromuscular agitation, 100 %; opsoclonus, 97 %; hypersalivation, 81 %; tachycardia, 82 %; hypertension, 49 %; vomiting, 38 %; fever, 28 %; respiratory distress, 33 %; and hypoxia, 18 %. Complications included rhabdomyolysis in 18 (20 %) and aspiration in 12 (13 %) patients. Intubation was required in 24 % of patients. The most frequently used agents to control symptoms were benzodiazepines (98 %) followed by opioids (69 %). Intravenous fluids were given to 84 %. Mean length of stay was 29 h (range, 6-73 h). There were no deaths. In addition to the classic findings of neuromuscular hyperactivity, opsoclonus, and hypersalivation, a high incidence of hyperadrenergic findings and respiratory compromise are noted in this series. A significant number of patients required mechanical ventilation. Benzodiazpines and opioids were the most common medications used to control symptoms.

Pediatric scorpion envenomation in the United States: morbidity, mortality, and therapeutic innovations

In the Southwestern United States, the venom of the scorpion Centruroides sculpturatus (common name bark scorpion) can cause serious and potentially fatal neurotoxicity, with young children most vulnerable to its effects. Historically, advances in the quality of supportive care have made significant improvements in morbidity and mortality. In recent years, the development of effective antivenom therapies has changed the landscape of caring for these patients. This article reviews the background, pathophysiology, diagnosis, and treatment options for C. sculpturatus envenomation. Recent advances in immunotherapy and subsequent implications for pediatric emergency care providers are discussed.

Serum levels and urine detection of Centruroides sculpturatus venom in significantly envenomated patients

INTRODUCTION

Envenomation by Centruroides sculpturatus can cause systemic signs and symptoms requiring treatment. The toxicokinetics of C. sculpturatus venom has not been described.

METHODS

Venom components were separated for cross-reactivity testing. Serum and urine collected from three patients envenomated by C. sculpturatus had venom levels determined by sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

Western blot analysis indicated recognition of C. sculpturatus venom by Alacramyn, an equine F(ab')(2) antivenom developed against Centruroides scorpion venoms, including C. sculpturatus. Serum venom levels in ng/mL with post-envenomation times in minutes (min) were as follows: 85-year-old woman = 8.2 (approximately 150), 2.8 (515), 1.6 (1,200); 14-month-old girl = 29.7 (approximately 50), 5.0 (729); 3-year-old girl = 11.1 (approximately 313), urine venom level of 9.0 (approximately 490).

CONCLUSION

There is sufficient venom cross-antigenicity among different Centruroides species to allow this ELISA technique with Alacramyn to determine serum and urine C. sculpturatus venom concentrations in envenomated patients.

Life-threatening stings, bites, infestations, and parasitic diseases

Bites, stings and infestations can be fatal. Anaphylaxis to vespids and bees can be prevented with immunotherapy. Patients should be referred to an allergist. The acute care and prevention of arthropod injury is discussed below.

Arthropods in dermatology

Arthropods are important in medicine for a multitude of reasons. Their bites and stings may induce allergic reactions, ranging from annoying to life-threatening. Many arthropod products are also capable of inciting allergic responses in sensitized persons. In recent years, bites and stings have gained greater attention owing to increased concern about disease transmission. A common hypersensitivity response to arthropod bites, stings, and products is papular urticaria. This eruption occurs primarily in children, who eventually "outgrow" this disease, probably through desensitization after multiple arthropod exposures. Papular urticaria is most often caused by fleas or bedbugs, but virtually any arthropod is capable of inducing such a reaction. Two arthropod classes of medical importance are the Arachnida (spiders, scorpions, ticks, and mites) and the Insecta (lice, fleas, bedbugs, flies, bees, and ants). Animals in these two classes are probably responsible for more morbidity and mortality worldwide than are any other group of venomous creatures. In general, the diagnosis of arthropod bites and stings is dependent on maintenance of a high index of suspicion and familiarity with the arthropod fauna not only in one's region of practice, but also in the travel regions of one's patients. Learning objective At the completion of this learning activity, participants should be familiar with the clinical manifestations caused by a variety of arthropods as well as the treatment and possible sequelae of arthropod attacks.

Arachnid envenomation

This article focuses on the medically relevant arachnid species found in North America and selected other arachnids from around the world. While it is largely still true that the geographic location of the envenomation assists in determining the species responsible, the booming trade in arachnids as exotic pets should prompt the clinician to inquire into this possibility. Expert advice should be sought in either case; species identification is critical in determining the need for and proper type of antivenom therapy.

Scorpion envenomations in young children in central Arizona

INTRODUCTION

Centruroides sculpturatus, also known as Centruroides exilicauda or bark scorpion, is the only scorpion native to the United States whose venom produces a potentially life-threatening illness, particularly in children.

OBJECTIVES

To describe the distribution of the severity grades following scorpion envenomations, the onset of clinical signs and symptoms, the time to deterioration, and side effects of antivenom treatment in children < or = 2 yrs of age.

METHODS

Prospective case-series with the following inclusion criteria of presumed scorpion envenomation, witnessed scorpion or signs and symptoms consistent with envenomation, patient age < or = 2 yrs, and the call was received by the poison center. After data were entered prospectively, a reviewer who was blinded as to the purpose of the study reviewed the charts. A second reviewer examined 10% of the charts for accuracy in coding. Envenomation severity grades were based on a previously described scorpion grading scale and were correlated with admission rates, clinical deterioration, and outcomes. Descriptive statistics (STATA & EXCEL) were used.

RESULTS

Of the 491 charts, 483 (98%) had adequate information available. The mean age was 20.8 [range 2-24] months with 133 patients (27.5%) presenting to an emergency department (ED), 86 patients (17.8%) received antivenom, and 25 patients (5.2%) were admitted. The p-value for kappa and the 95% confidence interval (CI) for interobserver reliability kappa score was 0.69 with CI (0.44-0.95). The grade distributions were Grade I = 343 cases (71%), Grade II = 8 cases (1.7%), Grade III = 49 cases (10.1%), and Grade IV = 83 cases (17.2%). The mean time to advancement of grade was 14 min (95% CI [10.97,17.06], 99% CI [10.04,18.03]) and the median time was < 1 min (range 0-140 min). Twenty-five patients (5.2%) were admitted, of which 13 were Grade III and 12 were Grade IV. Three patients (0.6% of total), all Grade IV envenomations, were intubated (95% CI [0.0021-0.0181] or an upper limit of 8.7 patients). Antivenom was administered to 86 patients (17.8%). The mean time of abatement of symptoms following antivenom was 31 [95% CI 10-82] min vs. 22.2 h [95% CI 12-46]. There was one acute reaction (rash) to antivenom administration and 49 cases (57%) of serum sickness.

CONCLUSIONS

Clinical progression following scorpion envenomation in children < or = 2 yrs old occurred on average within 14 min of envenomation with onset almost immediately. Serum sickness occurred in 57% of toddlers receiving antivenom and typically lasted less than 3 days. Admissions were less common among patients receiving antivenom.

A canine study of immunotherapy in scorpion envenomation

OBJECTIVE

To evaluate the effects of scorpion venom and antivenom in experimental envenomation.

DESIGN

Prospective, controlled animal study.

SETTING

University research laboratory

SUBJECTS

Twenty-nine anesthetized and ventilated dogs.

INTERVENTIONS

The first group of animals had venom alone (0.05 mg/kg). Animals from the second group had simultaneous administration of 10 ml of scorpion antivenom (SAV). In the third and fourth groups, 10 ml and 40 ml SAV, respectively, were injected 10 min following venom.

MEASUREMENTS AND RESULTS

Hemodynamic parameters using right heart catheter were recorded and dosage of catecholamines, neuropeptide Y (NPY), endothelin-1, and atrial natriuretic peptide (ANP) were performed at baseline and during 60 min following envenomation. In the control group, at 5 min, there was a sharp increase in pulmonary artery occluded pressure (PAOP, from 2 mmHg to 23 mmHg), mean arterial pressure (MAP, from 125 mmHg to 212 mmHg) and systemic vascular resistance (SVR, from 2450 dyn sec(-1 )m(5) to 5775 dyn sec(-1 )m(5), P<0.05 for all). Heart rate, cardiac output, and stroke volume decreased. There was a 40-fold increase in epinephrine and norepinephrine plasma concentrations. Circulating NPY and ANP dosages increased too. PAOP and MAP decreased thereafter to reach baseline levels. Simultaneous administration of SAV with venom totally offset the hallmarks of scorpion envenomation. Delayed administration of SAV at any dosage failed to alter the features of scorpion envenomation.

CONCLUSION

While simultaneous administration of SAV and scorpion venom is effective in preventing scorpion envenomation-related manifestations, delayed administration of SAV, either at standard or elevated dosages, failed to alter any of the scorpion envenomation features.

Antivenom treatment in arachnidism

Envenomation by arachnids causes significant medical illness worldwide. Scorpion sting is the most important arachnid envenomation causing adult morbidity and pediatric mortality. Important groups of spiders include the widow spiders (Latrodectus spp.), the recluse spiders (Loxosceles spp.), and two spiders confined to single countries: the Australian funnel web spider (Atrax and Hadronyche spp.) and the armed spider (Phoneutria spp.) from Brazil. There are four widow spider antivenoms available, including the Australian redback spider antivenom and the American black widow antivenom. Despite good in vitro animal work demonstrating effective neutralization with these antivenoms, and cross-reactivity between many species, there continues to be a reluctance to use them in some countries. They are both associated with a relatively low rate of allergic reactions. Redback antivenom is routinely used by the intramuscular route, which may not be as effective as intravenous use based on clinical experience and animal studies. Antivenoms are available for Loxosceles spp., but there is little evidence to support their effectiveness, particularly against local effects. The Australian funnel web spider causes severe neurotoxic envenomation, and antivenom appears to be effective in reported cases. An antivenom exists for the Brazilian armed spider, but is used in only a minority of cases. Many scorpion antivenoms exist worldwide, but there remains significant controversy regarding their efficacy. Animal and human venom level studies demonstrate neutralization of circulating venom in systemic envenomation. Clinical experience in countries where antivenom has been introduced suggests it has reduced pediatric mortality. However, three controlled trials demonstrated that antivenom was not effective, but these included few severe cases. Until controlled trials of antivenom in systemically envenomated patients are undertaken, antivenom use appears justified in severe envenomation. Although envenomation from arthropods is common, no antivenoms exist for these, excepting Lonomia caterpillars in South America, and Ixodes paralysis ticks in Australia.

Clinical toxinology--where are we now?

Clinical toxinology encompasses a broad range of medical conditions resulting from envenomation by venomous terrestrial and marine organisms, and also poisoning from ingestion of animal and plant toxins. Toxin-related disease is an important cause of morbidity and mortality worldwide, particularly in the tropical and subtropical continents. Snake bite is the single most important toxin-related disease, causing substantial mortality in many parts of Africa, Asia, and the Americas. The most important snake families are Viperidae and Elapidae, causing a range of clinical effects including local necrosis, neurotoxicity, coagulopathy and hemorrhage, myotoxicity and renal toxicity. These effects vary according to geography and group of snake. Arachnid envenomation results mainly in morbidity, particularly scorpion stings which can cause severe systemic envenomation. Spider bite is far less of a problem, and the majority of medically important cases can be attributed to widow spiders (Latrodectus spp.) and recluse spiders (Loxosceles spp.). Marine-related envenomations are common, but severe effects are less so. Plant and mushroom poisoning occur in most parts of the world, but the types and methods of poisoning vary considerably between continents. Management of toxin-related disease is often difficult, and in many cases meticulous supportive care is all that is available. The mainstay of treatment is the use of antivenoms for many envenomations and poisoning, although these do not exist for all dangerous organisms. Unfortunately antivenoms are not an economically viable product, so development and manufacture of these agents have been limited. This is now further worsened by a current shortage of antivenom. There is a need for improvement in the preventionand management of toxin-related disease. This will require well-designed studies to define the extent of the problem, initiatives to improve the prevention and management of these conditions, and development of new, and continuation of current, antivenom supplies.

Australian scorpion stings: a prospective study of definite stings

There is little information on scorpion stings in Australia. The aim of this study is to describe the circumstances and clinical effects of stings by Australian scorpions. Cases of scorpion stings were collected prospectively from calls and presentations to Australian poison information centres and emergency departments from February 2000 to April 2002. Only definite scorpion stings where the scorpion was immediately collected and expertly identified were included. There were 95 patients, 33 males and 62 females, with a mean age of 32 (SD 19.5; range 1-71) and 23 children (age<15 years). Three families of scorpions caused all stings: Buthidae (79), Bothruiridae (11, all Cercophonius spp.) and Urodacidae (five, all Urodacus spp.). The majority of stings (76%) were by one genus of scorpion Lychas spp. Seventy one percent of stings occurred between 6pm and 8am and 82 (86%) occurred indoors. Sixty percent of stings occurred on distal limbs. The median duration of effects was 6 h (interquartile range (IQR): 1-24 h). Immediate localised pain occurred in all cases and was severe in 76 cases (80%). Other local effects included red mark/redness (66%), tenderness (35%), numbness (12%) and paraesthesia (11%). Minor systemic effects (nausea, headache and malaise) occurred in 11% of cases. There were no deaths or major systemic envenoming. Less severe effects were observed for the larger Urodacus species, compared to Lychas spp. Scorpion stings in Australia do not appear to cause severe or life-threatening effects, even in children. This differs from other parts of the world, where severe envenoming is reported. The major clinical effect is severe pain, consistent with other scorpion stings. Most stings occurred indoors and at night.