Scorpion species of medical importance in the Brazilian Amazon: a review to identify knowledge gaps

Abstract

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.

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

“…Besides T . obscurus , the species Tityus metuendus , Tityus silvestri s, Tityus bastosi , Tityus apiacas , and Tityus strandi seem to be responsible for most envenomation cases in Brazilian Amazonia [ 106 , 108 ].…”

“…Recent scientific publications have described relevant human accidents with other scorpion species, especially in the Amazon region, which has the highest Tityus species diversity [17]. Besides T. obscurus, the species Tityus metuendus, Tityus silvestris, Tityus bastosi, Tityus apiacas, and Tityus strandi seem to be responsible for most envenomation cases in Brazilian Amazonia [106,108].…”

Antifungal activity of Rhopalurus crassicauda venom against Candida spp.

“…Inhabiting Amazonian savannah in the Brazilian northern and Guyana Southern ( di Caporiacco, 1947 ; Martins et al, 2021 ), the scorpion Rhopalurus crassicauda Lourenço, 2002 (synonym Rhopalurus amazonicus Lourenço, 1986 and Rhopalurus laticauda Thorell, 1876) ( Esposito et al, 2017 ; Martins et al, 2021 ) is a poorly studied species. There is only one study developed by Abreu et al (2020) revealing the structure and function of the major toxin (Rc1 with ∼7 kDa) and the isolation of a hyaluronidase.…”

Recombinant expression and antigenicity of two peptide families of neurotoxins from Androctonus sp.

“…Scorpion venoms contain neurotoxins that act directly, or in synergism with other molecules from the same venom, on mammalian or insect cell receptors that cause envenomation symptoms, paralysis, or death [ 1 - 3 ]. There are more than 2,000 scorpion species known in the world, but the venom of only a few species is dangerous to humans [ 4 ].…”

“…The two types of proteins differ slightly in their primary structures and belong to two distinct structural and immunological groups of neurotoxins. The mammalian neurotoxins Acra4, AaH1, and AaH3 represent one group, and the neurotoxins such AaH2, AmmV, and AmmVIII represent another group (see Table 1A and 1B ).…”