Update on the Epidemiology of Scorpion Envenomation in the South of Tunisia

Epidemiological, clinical, biological and evolutionary profile of scorpion envenomed children under one year to 15 years in the Souss Massa region of Morocco

Morocco is one of the main countries affected in North African with the scorpion envenomations. Faced with the threat, significant morbidity and a major risk of death especially in children, a detailed identification of scorpionic profile of stings remains important for health authorities at national or even regional level. The current study aims to establish the epidemiological, clinical, biological and evolutionary data of the scorpionism by analyzing 383 cases of scorpion stings in children from three age groups (<1 year, 1-5 years and >5 years), admitted at the Regional Hospital Hassan II-Agadir in the Souss Massa region during the period of 9 years and 10 months from January 2013 to October 2022. Our results showed that patients under 1 year of age presented the most severe cases and had the highest mortality rate. However, the clinical signs and symptoms observed illustrated severe damages to vital systems, particularly the cardiovascular, neurological and pulmonary systems, although the signs associated with the latter were present only in cases admitted in grades 2 and 3 for the three age categories studied. Fluctuations in vital constants (temperature and peripheral oxygen saturation, blood pressure, heart rate and respiratory rate), biochemical parameters (ASAT, ALAT, urea and blood creatine, as well as blood sugar) and CBC results revealed major functional disturbances in vital organs, especially in envenomated cases admitted in grade 3. A positive correlation was mentioned between the state of evolution and the various epidemiological parameters, digestive symptoms, as well as signs and symptoms linked to hemodynamic state, general and neurological state. The main interest is to illustrate the seriousness of scorpion envenomations, especially in the high-risk population, for whom an improved therapeutic approach in health centers will undoubtedly be reinforced, and the admission of immunotherapy, as a fundamental part of the treatment, remains important.

Development and Efficacy of the Antivenom Specific to Severe Envenomations in Morocco and North Africa: Advancements in Scorpion Envenomation Management

Scorpion envenomation poses a global public health issue, with an estimated 1,500,000 cases worldwide annually resulting in 2600 deaths. North Africa, particularly Morocco, experiences severe envenomations, mainly attributed to Androctonus mauretanicus and Buthus occitanus in Morocco, and Buthus occitanus and Androctonus australis hector in Algeria and Tunisia, with case numbers often underestimated. Current treatment relies mainly on symptomatic approaches, except in Morocco, where management is limited to symptomatic treatment due to controversies regarding specific treatment. In Morocco, between 30,000 and 50,000 scorpion envenomation cases are reported annually, leading to hundreds of deaths, mainly among children. Controversies among clinicians persist regarding the appropriate course of action, often limiting treatments to symptomatic measures. The absence of a specific antivenom for the venoms of the most lethal scorpions further exacerbates the situation. This study aims to address this gap by developing a monovalent antivenom against the endemic and most dangerous scorpion, Androctonus mauretanicus. The antivenom was produced by immunizing albino rabbits with a mixture of Androctonus mauretanicus venom collected from high-risk areas in Morocco. Immunizations were performed by subcutaneous injections at multiple sites near the lymphatic system, following an immunization schedule. Production control of neutralizing antibody titers was conducted through immunodiffusion. Once a sufficient antibody titer was achieved, blood collection was performed, and the recovered plasma underwent affinity chromatography. The efficacy of purified IgG was evaluated by determining the ED50 in mice, complemented by histological and immunohistochemical studies on its ability to neutralize venom-induced tissue alterations and the neutralization of toxins bound to receptors in the studied organs. The monovalent antivenom demonstrated specificity against Androctonus mauretanicus venom and effective cross-protection against the venom of the scorpions Buthus occitanus and Androctonus australis hector, highly implicated in lethal envenomations in the Maghreb. This study shows that the developed monovalent antivenom exhibits notable efficacy against local scorpions and a surprising ability to neutralize the most lethal envenomations in North Africa. These results pave the way for a new, more specific, and promising therapeutic approach to countering severe scorpion envenomations, especially in Morocco, where specific treatment is lacking.

French Scorpionism (Mainland and Oversea Territories): Narrative Review of Scorpion Species, Scorpion Venom, and Envenoming Management

Sixty-seven scorpion species have been described in France and its territories, where they have been found to be heterogeneously distributed. Indeed, only one species can be found on Réunion Island, while 38 species exist in French Guiana. The number of stings is also heterogenous, with up to 90 stings per 100,000 inhabitants occurring annually. Scorpion species can frequently be determined through simple visual factors, including species of medical importance (i.e., Buthus, Centruroides and Tityus). Scorpion venom is composed of local enzymes and peptides with a cysteine-stabilized α/β motif (NaTxs, Ktxs, Calcines), which allow for venom diffusion and the prey's incapacitation, respectively. Harmful scorpion species are limited to Centruroides pococki in the French West Indies, which can induce severe envenoming, and the Tityus obscurus and Tityus silvestris in French Guiana, which can cause fatalities in children and can induce severe envenoming, respectively. Envenomation by one of these scorpions requires hospital monitoring as long as systemic symptoms persist. Typical management includes the use of a lidocaine patch, pain killers, and local antiseptic. In the case of heart failure, the use of dobutamine can improve survival, and pregnant women must consult an obstetrician because of the elevated risk of preterm birth or stillbirth. France does not have scorpion antivenom, as scorpion stings are generally not fatal.

Neutralizing Dromedary-Derived Nanobodies Against BotI-Like Toxin From the Most Hazardous Scorpion Venom in the Middle East and North Africa Region

Scorpion envenoming is a severe health problem in many regions causing significant clinical toxic effects and fatalities. In the Middle East/North Africa (MENA) region, Buthidae scorpion stings are responsible for devastating toxic outcomes in human. The only available specific immunotherapeutic treatment is based on IgG fragments of animal origin. To overcome the limitations of classical immunotherapy, we have demonstrated the in vivo efficacy of NbF12-10 bispecific nanobody at preclinical level. Nanobodies were developed against BotI analogues belonging to a distinct structural and antigenic group of scorpion toxins, occurring in the MENA region. From Buthus occitanus tunetanus venom, BotI-like toxin was purified. The 41 N-terminal amino acid residues were sequenced, and the LD₅₀ was estimated at 40 ng/mouse. The BotI-like toxin was used for dromedary immunization. An immune VHH library was constructed, and after screening, two nanobodies were selected with nanomolar and sub-nanomolar affinity and recognizing an overlapping epitope. NbBotI-01 was able to neutralize 50% of the lethal effect of 13 LD₅₀ BotI-like toxins in mice when injected by i.c.v route, whereas NbBotI-17 neutralized 50% of the lethal effect of 7 LD₅₀. Interestingly, NbBotI-01 completely reduced the lethal effect of the 2 LD₅₀ of BotG50 when injected at 1:4 molar ratio excess. More interestingly, an equimolar mixture of NbBotI-01 with NbF12-10 neutralized completely the lethal effect of 7 and 5 LD₅₀ of BotG50 or AahG50, at 1:4 and 1:2 molar ratio, respectively. Hence, NbBotI-01 and NbF12-10 display synergic effects, leading to a novel therapeutic candidate for treating Buthus occitanus scorpion stings in the MENA region.

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.

Autopsy Findings in Case of Fatal Scorpion Sting: A Systematic Review of the Literature

Scorpion sting is a public health issue in several countries, particularly in America, the Middle East, India and Africa. The estimated annual global incidence of scorpion envenomings is about 1.5 million, resulting in 2600 deaths. Scorpions are Arthropoda characterized by a tail ending in a terminal bulbous (telson) containing paired venom glands and the stinger. There are 19 known families of scorpions and more than 2200 species, of which about 50 from the families of Buthidae, Hemiscorpiidae and Scorpionidae are harmful to humans. Scorpion venom is a complex structure composed of neurotoxic proteins, salts, acidic proteins and organic compounds, thereby having neurologic, cardiovascular, hematologic and renal side effects, in addition to local effects such as redness, pain, burning and swelling. When the sting is fatal, the mechanism of death is often related to cardiotoxicity with terminal pulmonary edema. However, the cholinergic excess or the neuromuscular excitation can provoke respiratory failure. Sometimes, death is due to an anaphylactic reaction to the envenoming. The purpose of this literature review is to evaluate the autopsy findings in scorpion sting-related deaths in order to better understand the pathophysiological mechanisms underlying them, thus helping pathologists in defining the correct diagnosis.