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

Evaluation of Scorpion Envenomation by Tityus trivittatus in Adults: An Analysis of Variables Related to Severity of Clinical Presentation

INTRODUCTION

In Argentina, the scorpion species Tityus trivittatus has been the species most commonly associated with serious injury and death.

METHODS

We performed a retrospective study of cases of T trivittatus envenomation that presented to the emergency department at an infectious disease hospital in Cordoba, Argentina, between December 2014 and February 2015. All cases were taxonomically confirmed using criteria established in the Argentine Ministry of Health national guidelines. The primary outcome was classification of clinical presentation (mild/moderate/severe). Classification of clinical presentation was performed in a post hoc fashion using the national guidelines and compared to the classification of clinical presentation given to patients at the time of diagnosis in the emergency department.

RESULTS

We included 450 individuals with T trivittatus envenomation. The median age of was 36 y (interquartile range 25-52), and 57% were female. In the emergency department, only 5 patients (<1%) were diagnosed as moderate cases and received antivenom; all other cases were diagnosed as mild. Conversely, in our post hoc classification of clinical presentations, 280 patients had mild presentations, 170 had moderate presentations, and no patients had severe presentations. In our cohort, there were no deaths, no inpatient hospital admissions, and no requirements for continuous cardiac monitoring. We found that age >50 y, (odds ratio [OR] 2.5, P<0.001), time from sting to presentation >120 min (OR 2.6, P=0.02), and pre-existing hypertension (OR=3.9, P<0.001) were all independently associated with worse post hoc classification severity.

CONCLUSIONS

Our study exposed factors associated with moderate presentations of scorpion envenomation and proposes the option of conservative treatment for affected adults.

The epidemiology and severity of scorpion envenoming in South Africa as managed by the Tygerberg Poisons Information Centre over a 10 year period

INTRODUCTION

South Africa has a wide distribution of scorpion species, yet limited data are available regarding the incidence and severity of scorpion envenomation. The aim of this study was to analyse South African epidemiological data of scorpion stings and envenomation as reported to the Tygerberg Poisons Information Centre (TPIC).

METHODS

A retrospective analysis was conducted of scorpion-related telephonic consultations to the TPIC over a ten year period (1 January 2005 to 31 December 2014). Data were entered onto a Microsoft Excel® spreadsheet and descriptive statistics are presented for all variables. Associations with severity of envenomation are presented as odds ratios (OR) with 95% confidence intervals (95%CI).

RESULTS

During the study period 52,163 consultations were processed by the TPIC of which 740 (1.4%) cases involved scorpion stings. Of these, 146 (19.7%) cases were deemed serious envenomations. Antivenom was recommended to be administered in 131 (90%) of these cases. Healthcare professionals made most calls (63%), but were less likely to phone for non-serious cases (OR 0.16; 95%CI 0.09 to 0.29). The Western Cape Province had the highest incidence of calls (6.9 scorpion-related calls/100 000 people). Adults (>20 years) were victims in 71.4% of cases, and were more likely to experience less serious stings (OR 0.57; 95%CI 0.37 to 0.86). The TPIC was consulted within six hours of the sting occurring in 356 (48.1%) cases with a significant association to less severity (OR 3.51; 95%CI 1.9 to 6.3). Only 2% (15) of the scorpions were available for identification.

CONCLUSION

The incidence of severe scorpionism to the TPIC was low. Care should be taken when children are involved and when calls are received more than six hours after the sting. TPIC consultants as well as healthcare professionals working in semi-arid regions should be aware of these high risk populations.

Determination of median effective dose (ED50) of scorpion antivenom against scorpion envenomation using a newly developed formula

BACKGROUND

About 50 species of scorpions cause fatal scorpionism worldwide. Most of these are members of the Buthidae family, and include, among others, Mesobuthus eupeus, Androctonus crassicauda, Leiurus abdullahbayrami, Leiurus quinquestriatus, Tityus pachyurus and Androctonus australis. Because high doses of scorpion venom and antivenom can cause death and hypersensitive reactions, there is a need to develop a formula that can be used to calculate both lethal and effective doses for scorpion venom and antivenom, respectively, thereby obviating the need for laboratory experiments.

METHODS

In view of this, a literature search was carried out with the aim of modifying the formula (LD 50 = ED 50 3 × W a × 10 - 4 ) for calculation of the median lethal dose (LD50) of scorpion venom and the ED50 of antivenom. The human equivalent dose (HED) formula was assessed for extrapolation of LD50 and ED50 from animals to human for comparison and relevance with the new formula.

RESULTS

The findings showed that the newly developed formula (LD50 = ED50 1/3 × W a  × 10-4) yielded results that are very close to the reported values. Therefore, the newly developed and HED formulas can be used for calculation of LD50 and ED50 values for scorpion venom and antivenom, respectively.

CONCLUSION

The new formula yielded better results than the HED formula, confirming its predictive validity, precision, and reliability, thereby obviating the need for rigorous experiments and justifying the principles of reduction, refinement, and replacement (3Rs).

Acute kidney injury and pancreatitis due to scorpion sting: case report and literature review

Despite the high number of accidents due to scorpion stings in Brazil, severe cases in adults are seldomly reported. In the Northeast region of Brazil, Tityus stigmurus is the most prevalent species. A 69 year-old woman who was stung by a scorpion attended the emergency room 5 hours after envenomation. She got worse due to abdominal pain. Clinical findings were concordant with class III scorpion envenomation (major systemic manifestations), complicated by acute kidney injury and acute pancreatitis. Intensive supportive therapy was adopted. In the follow-up, 3 months later, she was completely recovered. This report is being brought to recommend the thorough management of victims of scorpion accidents, enabling early diagnosis of severe complications, which could lead to death if aggressive supportive measures are not early and adequately taken.

Intracerebral Hemorrhage Secondary to Scorpion Toxin in the Northwest of Argentina; A Case Report

Scorpionism is the clinical picture resulting from the inoculation of scorpion venom. It is considered a major public health problem, especially in countries with low resources and tropical or subtropical climate. Poisoning can be fatal especially in the first hours due to respiratory and / or cardiovascular collapse. The compromise of the central nervous system (CNS) is infrequent but varied and complex, being able to be triggered due to multiple and different neurotoxic properties of the toxin. We report here a severe case of poisoning with cardiovascular and neurological compromise in an endemic region of Argentina. After cardiorespiratory stabilization, neurological deterioration is detected secondary to intracerebral hemorrhage that required surgery and multimodal neuromonitoring. The outcome was fatal due to multiple neurological and systemic complications. Scorpion sting poisoning is a true neurologic and neurosurgical life-threatening emergency.

Effects of Brazilian scorpion venoms on the central nervous system

In Brazil, the scorpion species responsible for most severe incidents belong to the Tityus genus and, among this group, T. serrulatus, T. bahiensis, T. stigmurus and T. obscurus are the most dangerous ones. Other species such as T. metuendus, T. silvestres, T. brazilae, T. confluens, T. costatus, T. fasciolatus and T. neglectus are also found in the country, but the incidence and severity of accidents caused by them are lower. The main effects caused by scorpion venoms - such as myocardial damage, cardiac arrhythmias, pulmonary edema and shock - are mainly due to the release of mediators from the autonomic nervous system. On the other hand, some evidence show the participation of the central nervous system and inflammatory response in the process. The participation of the central nervous system in envenoming has always been questioned. Some authors claim that the central effects would be a consequence of peripheral stimulation and would be the result, not the cause, of the envenoming process. Because, they say, at least in adult individuals, the venom would be unable to cross the blood-brain barrier. In contrast, there is some evidence showing the direct participation of the central nervous system in the envenoming process. This review summarizes the major findings on the effects of Brazilian scorpion venoms on the central nervous system, both clinically and experimentally. Most of the studies have been performed with T. serrulatus and T. bahiensis. Little information is available regarding the other Brazilian Tityus species.

Value of troponin levels in the diagnosis of cardiac dysfunction in moderate scorpion envenomation

Context:

Cardiac dysfunction is one of the most serious consequences of scorpion envenomation. The best tool to evaluate cardiac function is echocardiography, but it is not available at all emergency departments. Many studies aimed to describe biological predictive factors of cardiac dysfunction in scorpion envenomation. Troponin is one of these biomarkers but its correlation with myocarditis is not well established. The aim of this study was to evaluate correlation between troponin levels and cardiac dysfunction in moderate scorpion envenomation.

Methods:

A retrospective monocentric study including patients admitted in the emergency department for moderate scorpion envenomation with troponin measurement during their early management. On arrival, an electrocardiogram and a chest X-ray were realized for all patients.

Results:

We enrolled 132 patients with a mean age at 31.3 ± 24.4 years and a 1.35 sex-ratio. All patients had moderate systemic manifestations. There were 28 patients with clinical manifestations of cardiac dysfunction without life-threatening troubles (21.2%). Troponin was undetectable in 69 patients (56%). The mean value of troponin level (pg/ml) was higher in patients with clinical manifestations of left ventricular dysfunction (1.80 ± 3.8 vs. 0.11 ± 0.5; p = 0.02). Troponin levels were significantly higher in patients with positive T wave on electrocardiogram.

Conclusion:

In patients with moderate scorpion envenomation with positive T wave, high values of troponin suggest the presence of cardiac dysfunction.

Comparative analyses and implications for antivenom serotherapy of four Moroccan scorpion Buthus occitanus venoms: Subspecies tunetanus, paris, malhommei, and mardochei

Temporary passive immunity such as serotherapy against venoms requires the full knowledge of all venom's components. Here, four venoms from Moroccan common yellow scorpions belonging to Buthus occitanus, subspecies tunetanus, paris, malhommei, and mardochei, all collected in four different restricted areas, were analysed in deep. They were fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) and their molecular masse profile determined by off-line MALDI-TOF mass spectrometry. Characterisation of their main components was achieved by enzyme-linked immunosorbent assay (ELISA) using specific antisera against the major lethal scorpion toxins identified so far, i.e. voltage-gated sodium channels (Na_v) modulators α- and β-toxins, as well as diverse potassium channel pore blocker toxins. For fractions with identical RP-HPLC retention times, we observe that their relative quantities show large differences. Moreover, identical masses present simultaneously in the four venoms are infrequent. ELISAs show that the majority of the RP-HPLC compounds cross-react with the antiserum against the "α-like" toxin Bot I, which has been previously identified in the Algerian Buthus occitanus tunetanus venom. Moreover, minor fractions were recognised by the antiserum against the highly lethal "classical" α-toxin of reference AaH II from the Androctonus australis venom. As such, our results bring new sights for further improving scorpion venom serotherapy in Morocco.

Perinatal effects of scorpion venoms: maternal and offspring development

Scorpion envenomation is a public health problem, especially in tropical and subtropical countries. Considering the high incidence of scorpionism in some areas, pregnant women and nursing mothers may be possible victims. Scorpion stings alter the release of neurotransmitters and some cytokines. These mediators act as organizers and programmers in the adequate formation of the nerves, and non-physiological concentrations of them during the brain organization originate disorders and diseases that can appear later in the life of the individual. Despite the importance of this subject, there are only a few studies showing the effects of scorpion venom on maternal reproductive development, in the morphology and physical and behavioral development of offspring. The present review article summarizes the major findings on this issue. Biochemical changes in the blood – such as hyperglycemia, increase on the level of sodium and on the creatinine concentration – are observed after scorpion sting in humans and experimental animals. Some studies in the literature demonstrate that the scorpion venom affects the maternal reproductive development in humans and in experimental animals, increasing the frequency and amplitude of uterine contraction and the number of resorptions. The venom can also lead to some alterations in the embryonic or fetal development increasing the total weight of fetuses and of some organs. Moreover, it affects the general activity and locomotion during childhood and adulthood, and the anxiety level in adult females and males. It also alters the number of hippocampal neurons and interferes in the level of some cytokines. Altogether, it is evident that the venom, when administered during the pregnancy or lactation, affects the development of the offspring. Studies are being conducted to determine the actual participation of the venom in the development of the offspring, and to what extent they are detrimental to animal development.

Antivenom Evaluation by Electrophysiological Analysis

Scorpion stings on humans are medically relevant because they may contain toxins that specifically target ion channels. During antivenom production, pharmaceutical companies must use a large number of experimental animals to ensure the antivenom's efficacy according to pharmacopeia methods. Here we present an electrophysiological alternative for the evaluation of horse antivenoms produced against two species of Moroccan scorpions: Buthus mardochei and Androctonus mauretanicus. Human sodium and potassium channels and acetylcholine nicotinic receptors were analyzed by standard patch-clamp techniques. The results showed that the antivenom is capable of reversing ion current disruption caused by the venom application. We propose the use of this in vitro technique for antivenom evaluation as an alternative to using a large number of live animals.