Amazonian scorpions and scorpionism: integrating toxinological, clinical, and phylogenetic data to combat a human health crisis in the world's most diverse rainfores

Exploring the potential of Brazilian Amazonian scorpion venoms: A comprehensive review of research from 2001 to 2021

The Amazon biome is home to many scorpion species, with around two hundred identified in the region. Of these, forty-eight species have been reported in Brazil so far and six of them are of medical importance: Tityus apiacas, T. metuendus, T. obscurus, T. raquelae, T. silvestris, and T. strandi. Three non-medically important species have also been studied: Opisthanthuscayaporum, Brotheas amazonicus and Rhopalurus laticauda. The venom of the scorpion T. obscurus is the most studied, followed by O. cayaporum. We aim to update the study of these Amazonian scorpion species. We will explore the harmful and beneficial properties of scorpion venom toxins and how they could be applied in drug development. This systematic review will focus on collecting and analyzing venoms from scorpions in Brazil. Only papers on Amazonian scorpion venom studies published between 2001 and 2021 (scientific articles, theses, and dissertations) were selected, based on the lists of scorpions available in the literature. Species found in the Amazon but not confirmed to be Brazilian were omitted from the review. Theses and dissertations were chosen over their derived articles. We found 42 eligible studies (13 theses, 27 articles and 2 patents) out of 17,950 studies and a basic statistical analysis was performed. The literature showed that T. obscurus was the most studied venom with 28 publications, followed by O. cayaporum with seven articles, B. amazonicus with four articles, T. metuendus with two article and R. laticauda with one article. No publication on the characterization of T. silvestris and T. apiacas venoms were found during the reviewed period, only the clinical aspects were covered. There is still much to be explored despite the increasing number of studies conducted in recent years. Amazonian scorpions have promising potential for pharmaceutical and clinical applications.

The complex repertoire of Tityus spp. venoms: Advances on their composition and pharmacological potential of their toxins

Animal venoms are a rich and complex source of components, including peptides (such as neurotoxins, anionic peptides and hypotensins), lipids, proteins (such as proteases, hyaluronidases and phospholipases) and inorganic compounds, which affect all biological systems of the envenoming victim. Their action may result in a wide range of clinical manifestations, including tachy/bradycardia, hyper/hypotension, disorders in blood coagulation, pain, edema, inflammation, fever, muscle paralysis, coma and even death. Scorpions are one of the most studied venomous animals in the world and interesting bioactive molecules have been isolated and identified from their venoms over the years. Tityus spp. are among the scorpions with high number of accidents reported in the Americas, especially in Brazil. Their venoms have demonstrated interesting results in the search for novel agents with antimicrobial, anti-viral, anti-parasitic, hypotensive, immunomodulation, anti-insect, antitumor and/or antinociceptive activities. Furthermore, other recent activities still under investigation include drug delivery action, design of anti-epileptic drugs, investigation of sodium channel function, treatment of erectile disfunction and priapism, improvement of scorpion antivenom and chelating molecules activity. In this scenario, this paper focuses on reviewing advances on Tityus venom components mainly through the modern omics technologies as well as addressing potential therapeutic agents from their venoms and highlighting this abundant source of pharmacologically active molecules with biotechnological application.

Proteomic profile of the venom of three dark-colored Tityus (Scorpiones: Buthidae) from the tropical rainforests of Costa Rica

OBJECTIVE

We aimed to elucidate the potential differences in the venom peptide sequences of three Tityus species from Costa Rican rainforests: T. jaimei, T. championi and T. dedoslargos, compared to T. cf. asthenes from Colombia, which could explain the low level of scorpionism in Costa Rica, evidenced by the lack of epidemiological data.

METHODOLOGY

We applied venom proteomics of peptides purified by RP-HPLC and compared the obtained sequences from venoms of these Tityus species to the sequences previously identified from Tityus inhabiting other Central and South American regions.

RESULTS

Venom proteome analysis evidences that most of the putative peptide toxins identified in Costa Rican dark-colored Tityus are very similar to those present in other T. (Atreus) from the region.

CONCLUSIONS

Our study suggests that, in the case of potential envenomation by Tityus in Costa Rica, the same level of toxicity should be observed, compared to other cases caused by members of the subgenus from other geographical localities. On the other hand, compared to countries with more accelerated urban expansion, Costa Rican Tityus still inhabit secondary rainforests and do not commonly share the same spaces with humans, so the lack of epidemiological evidence of medical emergencies caused by envenoming by this scorpion group could be more related to ecological and demographic factors and less attributed to the characteristics of the venom.

Scorpion envenomation in the neotropical savannah: Environmental predictors and years of lost life

Scorpion stings envenomation (SSE) is a growing medical concern in Brazil, particularly in the state of Minas Gerais, which has recorded a significant number of incidents. This study aimed to investigate the potential predictors of scorpion sting incidence and evaluate the cost-effectiveness of interventions in Minas Gerais. Generalized Estimating Equations (GEE) models were constructed using socioeconomic and environmental variables as predictors and scorpion sting incidence as the response variable. The analysis revealed that mean annual temperature and major land use type were significant predictors of scorpion sting incidence, while precipitation and socioeconomic variables showed no relationship with incidence. The total number of cases and annual incidence of scorpion stings overlapped with regions experiencing higher forest conversion and agricultural land use, as well as higher temperatures. The estimated Disability-Adjusted Life Years (DALY) for scorpion sting incidents in Minas Gerais was substantial, indicating the need for effective prevention and treatment measures. The cost per DALY averted varied among municipalities, with some requiring minimal investment while others needing significant funding to address the scorpion risk. Mean annual temperature emerged as the main risk factor for scorpion stings, contributing to increased costs associated with antivenom treatment. These findings highlight the importance of considering environmental factors and implementing targeted interventions to mitigate scorpion sting incidents and reduce associated morbidity and mortality.

Lipidomic profiling of the Brazilian yellow scorpion venom: new insights into inflammatory responses following Tityus serrulatus envenomation

Due to the high prevalence and clinical relevance, scorpionism is a critical public health issue in several Brazilian regions. Tityus serrulatus, commonly known as the Brazilian yellow scorpion, is the most venomous genus found in Brazilian fauna and associated with severe clinical manifestations such as localized pain, hypertension, sweating, tachycardia and complex hyperinflammatory responses. In general, T. serrulatus venom contains a complex mixture of active compounds, including proteins, peptides, and amino acids. Although knowledge of the protein fractions of scorpion venom is available, venom lipid components are not yet comprehensively known. The aim of the present study was to determine and characterize the lipid constituents/profile of the T. serratus venom utilizing liquid chromatography coupled with high-resolution mass spectrometry. Lipid species (164 in total) belonging to 3 different lipid categories, glycerophospholipids, sphingolipids, and glycerolipids, were identified. A further search on MetaCore/MetaDrug platform, which is based upon a manually curated database of molecular interactions, molecular pathways, gene-disease associations, chemical metabolism, and toxicity information, exhibited several metabolic pathways for 24 of previously identified lipid species, including activation of nuclear factor kappa B and oxidative stress pathways. Further several bioactive compounds, such as plasmalogens, lyso-platelet-activating factors, and sphingomyelins, associated with systemic responses triggered by T. serrulatus envenomation were detected. Finally, lipidomic data presented provide advanced and valuable information to better comprehend the mechanisms underlying the complex pathophysiology induced by T. serrulatus envenomation.

On the noxious black Amazonian scorpion, Tityus obscurus (Scorpiones, Buthidae): Taxonomic notes, biology, medical importance and envenoming treatment

Tityus obscurus has caused mild, moderate and severe accidents of medical relevance in the eastern Brazilian Amazon and French Guiana. Tityus obscurus has sexual dimorphism although males and females have uniform black coloration. In the Amazon, one of the habitats of this scorpion is seasonally flooded forests (igapós and várzeas). However, most stings occur in terra firme forest areas (non-flooded region), where most rural communities are located. Adults and children stung by T. obscurus may experience an "electric shock" sensation for more than 30 h after the sting. Our data shows that people inhabiting remote forest areas, including rubber tappers, fishermen and indigenous people, with no access to anti-scorpion serum, use parts of native plants, such as seeds and leaves, against pain and vomiting caused by scorpion stings. Although there is a technical effort to produce and distribute antivenoms in the Amazon, many cases of scorpion stings are geographically unpredictable in this region, due to the lack of detailed knowledge of the natural distribution of these animals. In this manuscript, we compile information on the natural history of T. obscurus and the impact of its envenoming on human health. We identify the natural sites that host this scorpion in the Amazon, in order to warn about the risk of human envenoming. The use of specific antivenom serum is the recommended treatment for accidents involving venomous animals. However, atypical symptoms not neutralized by the available commercial antivenom are reported in the Amazon region. Facing this scenario, we present some challenges to the study of venomous animals in the Amazon rainforest and possible experimental bottlenecks and perspectives for establishing a method aimed at producing an efficient antivenom.

Case Report: Fatal Scorpion Envenomation in a Shuar Child by Tityus cisandinus from Amazonian Ecuador: A Call for Specific Antivenom Availability in the Amazon Basin

Envenomation by scorpions belonging to the genus Tityus can be life threatening in the Americas, particularly in the Amazon Basin. We report a 4-month-old Ecuadorean boy of Shuar origin stung by a scorpion identified as Tityus cisandinus in the Amazonian province of Morona Santiago, presenting with pulmonary edema and systemic inflammation. We administered immunotherapy using the scorpion antivenom available in Ecuador, of Mexican origin (anti-Centruroides). Catecholamine discharge-related events such as hyperglycemia and thrombocytosis were resolved after treatment but leukocytosis did not, suggesting that factors associated with the sting-admission delay and specificity of antivenom played a role in the envenomation outcome. Cardiorespiratory arrest determined a fatal outcome, despite specific maneuvers. The case severity and the limited supply of nonspecific scorpion antivenoms in problematic areas of Amazonian Ecuador and elsewhere in northwestern Amazonia are discussed in regard to the need for specific therapeutic immunoglobulins in the area and in the Amazon Basin as a whole.

Scorpion envenomation in Brazil: Current scenario and perspectives for containing an increasing health problem

Opportunistic scorpion species can colonize urban environments, establishing high-density communities that enhance the chances of human accidents. This scenario has been taking place in Brazil, in which some Tityus species have taken city centers, causing an explosion in the number of scorpion envenoming cases. The characteristics of this scorpionism epidemic in Brazil is discussed in the present work. The number of Brazilian scorpion stings has surpassed 120,000 cases in 2017, and has been maintained above this number ever since, representing a more than 3-fold increase in 10 years, which was higher than the number of cases for most of the neglected tropical diseases in the country. The escalation in scorpionism cases is even higher in some regions of Brazil. Fortunately, the proportion of mild cases has also increased in the analyzed period, as well as the number of victims seeking for medical attention within the first hour after the accident. The species Tityus serrulatus, Tityus stigmurus, Tityus bahiensis, and Tityus obscurus are traditionally accountable for most of the scorpion accidents in different regions of Brazil, but other species deserve to be closely watched. Despite scorpionism being a notable health problem in Brazil, accident prevention and pest control regarding this venomous animal have not been properly addressed by the scientific community nor by policy makers. Therefore, this review also aims to point possible fields of research that could help to contain the aggravation of the current scorpionism landscape in Brazil.

An overview of Tityus cisandinus scorpion venom: Transcriptome and mass fingerprinting reveal conserved toxin homologs across the Amazon region and novel lipolytic components

Tityus cisandinus, a neglected medically important scorpion in Ecuadorian and Peruvian Amazonia, belongs to a complex of species related to the eastern Amazon endemic Tityus obscurus, spanning a distribution of ca. 4000 km. Despite high morbidity and mortality rates, no effective scorpion antivenom is currently available in the Amazon region. Knowledge of the structural/functional relationships between T. cisandinus venom components and those from related Amazonian species is crucial for designing region-specific therapeutic antivenoms. In this work, we carried out the first venom gland transcriptomic study of an Amazonian scorpion outside Brazil, T. cisandinus. We also fingerprinted its total venom through MALDI-TOF MS, which supported our transcriptomic findings. We identified and calculated the expression level of 94 components: 60 toxins, 25 metalloproteases, five disulfide isomerases, three amidating enzymes, one hyaluronidase, and also uncovered transcripts encoding novel lipolytic beta subunits produced by New World buthid scorpions. This study demonstrates the high similarity between T. cisandinus and T. obscurus venoms, reinforcing the existence of a neglected complex of genetically and toxinologically related Amazonian scorpions of medical importance. Finally, we demonstrated the low recognition of currently available therapeutic sera against T. cisandinus and T. obscurus venoms, and concluded that these should be improved to protect against envenomation by Amazonian Tityus spp.