Scorpionism is a relevant medical condition in Brazil. It is responsible for most accidents involving venomous animals in the country, which leads to severe symptoms that can evolve to death. In recent years, an increase of almost 50% in the incidence of scorpionism has been observed in the Northern Region, where the highest severity of envenoming has been notified since the beginning of the 21^st century. This review aims to provide an in-depth assessment of public data and reports on symptoms and epidemiology of envenoming, ecological aspects of scorpions, and characterization of venoms and toxins to access the gaps that need to be filled in the knowledge of the scorpion species of medical importance from the Brazilian Amazon. A systematic search using the string words “Amazon” and “scorpion” was performed on 11 databases. No restriction on date, language or status of the publication was applied. Reports not related to the Brazilian Amazon were excluded. Therefore, 88 studies remained. It is shown that populations of scorpions of medical importance, even of the same species, may present significant toxic variations peculiar to some regions in the Brazilian Amazon, and commercial scorpion antivenoms were not able to shorten the intensity and duration of neurological manifestations in patients stung by T. silvestris, T. apiacas or T. obscurus. It is also highlighted that the toxins responsible for triggering these alterations have not been elucidated yet and this is a fruitful field for the development of more efficient antivenoms. Furthermore, the geographic distribution of scorpions of the genus Tityus in the Brazilian Amazon was revised and updated. The cumulative and detailed information provided in this review may help physicians and scientists interested in scorpionism in the Brazilian Amazon.

Scorpionism is a growing public health concern in Brazil, with the Amazon region presenting the highest mortality rates but remaining understudied, especially regarding local scorpion venoms composition. This study presents the first comprehensive biochemical characterization of venoms from three Amazonian species—Tityus metuendus (TmetuV), Tityus silvestris (TsilvV), and Brotheas amazonicus (BamazV)—using an integrated approach combining Multi-Enzymatic Limited Digestion (MELD)-based bottom-up proteomics, high-resolution LC-MS/MS, chromatography, zymography, and enzymatic assays. Tityus serrulatus venom was included as a reference. Significant biochemical differences were observed: TsilvV was rich in 20–30 kDa proteins and showed strong metalloprotease activity; BamazV exhibited high molecular weight proteins and potent phospholipase A₂ (PLA₂) activity but lacked proteolytic and fibrinogenolytic activities; TmetuV showed the highest hyaluronidase activity and abundance of α-KTx neurotoxins. Zymography revealed a conserved ~45 kDa hyaluronidase in all species. Three novel components were partially characterized: BamazPLA₂ (Group III PLA₂), Tmetu1 (37-residue α-KTx), and TsilvMP_A (a metalloprotease homologous to antarease). This is the first application of MELD-based proteomics to Amazonian scorpion venoms, revealing molecular diversity and functional divergence within Tityus and Brotheas, emphasizing the need for region-specific antivenoms. These findings provide a foundation for future pharmacological studies and the discovery of bioactive peptides with therapeutic potential.

Leishmaniasis is a vector-transmitted zoonosis caused by different species of the genus Leishmania, with a wide clinical spectrum. It is a public health problem aggravated by a series of limitations regarding treatment. In the search for new therapeutic alternatives, scorpion venoms are a source of multifunctional molecules that act against the natural resistance of pathogens. This work evaluated the antileishmanial potential of Brotheas amazonicus and Tityus metuendus venoms against the promastigote forms of Leishmania amazonensis e Leishmania guyanensis. The venoms of B. amazonicus and T. metuendus were evaluated for their constituents using Fourier Transform Infrared (FTIR). Growth inhibition and death of promastigotes were evaluated in the presence of diferente crude venom concentrations (100 µg/mL, 50 µg/mL, 10 µg/mL, 1 µg/mL) after one hour of incubation at 25 °C. The FTIR spectra of both venoms exhibited bands in approximate regions, revealing that both exhibit similar functional groups. Crude venom from both scorpion species showed similar or superior leishmanicidal effects to the standart drug N-methylglucamine antimoniate. At the highest concentration of 100 µg/mL, cultures of L. guyanensis treated with the venom of B. amazonicus showed the highest mortality percentages, above 28%, while T. metuendus venom showed the highest activity against L. amazonensis, with mortality above 7%. This preliminar study demonstrates that B. amazonicus and T. metuendus venoms can be important tools in the search for new drugs Against leishmaniasis. Next step involves evaluating the activity against the amastigote forms and purifying the venom proteins in order to identify the best anti-leishmania candidates.

Scorpions are of particular interest in cytogenomic studies, as they can present a high incidence of chromosomal rearrangements heterozygous in natural populations. In this study, we cytogenetically analyzed four species of Chactidae. In Brotheas, 2n = 40 was observed in Brotheas silvestris, 2n = 48 in Brotheas paraensis, and 2n = 50 (cytotype A) or 2n = 52 (cytotype B) among populations of Brotheas amazonicus. Our results showed a bimodal karyotype in Neochactas parvulus, 2n = 54, with microchromosomes and a concentration of constitutive heterochromatin in macrochromosomes. The 45S rDNA is located in only one pair of the karyotype, with different heteromorphisms of clusters of this rDNA in the cytotype B of B. amazonicus, with NOR-bearing chromosomes involved in multi-chromosomal associations during meiosis I. The U2 snDNA was mapped in the interstitial region of distinct karyotype pairs of three Chactidae species. Our results indicate the possible formation of cryptic species in B. amazonicus; the different 45S rDNA configurations in the genome of this species may result from amplification and degeneration. We suggest that the bimodal karyotype in N. parvulus results from fusion/fission events and that the unequal distribution of repetitive DNAs between macro and microchromosomes contributes to the maintenance of its asymmetry.

The natural beauty of the Amazon attracts tourists and natural historians from all over the world. ¹ Simonetti S.R. Tourism and intangible heritage of the village of Paricatuba: the history in the ruins. Tourism. 2019; 1 : 85-106 Google Scholar ^,2 Peralta N. Ecotourism as an incentive to biodiversity conservation: the case of Uakari Lodge, Amazonas, Brazil. Uakari. 2012; 8 : 75-94 Google Scholar In the region of Manaus, capital of the state of Amazonas, the tourist attractions include places such as museums, jungle hotels, zoos, walks through the forest, rivers, and beaches. ² Peralta N. Ecotourism as an incentive to biodiversity conservation: the case of Uakari Lodge, Amazonas, Brazil. Uakari. 2012; 8 : 75-94 Google Scholar A popular site is the ruins of Village of Paricatuba (3°04'58.1"S 60°14'04.6"W), located on the banks of the Rio Negro, Municipality of Iranduba, state of Amazonas, Brazil. ¹ Simonetti S.R. Tourism and intangible heritage of the village of Paricatuba: the history in the ruins. Tourism. 2019; 1 : 85-106 Google Scholar These buildings opened in the 19th century and served as an agricultural school, hospital, and public prison. ¹ Simonetti S.R. Tourism and intangible heritage of the village of Paricatuba: the history in the ruins. Tourism. 2019; 1 : 85-106 Google Scholar During our scientific expedition (November 2020) to this site (Figure 1, top), we identified 15 adult specimens of Tityus dinizi Lourenço, 1997, inside these ruins. An adult male found inside the buildings was approximately 1 m above the ground (Figure 1, bottom). In Brazil, there are a total of 170 species of scorpions known, ³ Lourenço W.R. Scorpions of Brazil. Les Editions de l’If Paris, 2002 Google Scholar ^,4 Martins J.G. Santos G.C. Procópio R.E. Arantes E.C. Bordon K.C.F. Scorpion species of medical importance in the Brazilian Amazon: a review to identify knowledge gaps. J Venom Anim Toxins Incl Trop Dis. 2021; 27 e20210012 Google Scholar and approximately 28% of this fauna occurs in the state of Amazonas. ⁴ Martins J.G. Santos G.C. Procópio R.E. Arantes E.C. Bordon K.C.F. Scorpion species of medical importance in the Brazilian Amazon: a review to identify knowledge gaps. J Venom Anim Toxins Incl Trop Dis. 2021; 27 e20210012 Google Scholar Figure 1 Historic site of Paricatuba in the state of Amazonas, Brazil (top); Tityus dinizi on an inner wall of the building (bottom). View Large Image Figure Viewer Download Hi-res image