Scorpion envenoming in Morona Santiago, Amazonian Ecuador: Molecular phylogenetics confirms involvement of the Tityus obscurus group

Abstract Scorpion envenomingby species in the genus Tityus is hereby reported from rural locations in the Amazonianprovince of Morona Santiago, southeastern Ecuador. Twenty envenomingcases (18 patients under 15 years of age) including one death (a 4-year-old male) were recorded at the Macas General Hospital, Morona Santiago, between January 2015 and December 2016 from the counties of Taisha (n = 17), Huamboyo (n = 1), Palora (n = 1), and Logrono (n = 1). An additional fatality from 2014 (a 3-year-old female from Nayantza, Taisha county) is also reported. Leukocytosisand low serum potassium levels were detected in most patients. We observed a significant negative correlation between leukocytosisand hypokalemia. Scorpionsinvolved in three accidents from Macuma, Taisha County, were identified as genetically related to Tityus obscurus from the Brazilian Amazonianregion based on comparison of mitochondrial DNA sequences encoding cytochrome oxidase subunit I. These cases, along with previously reported envenomingfrom northern Manabi, reinforce the notion that scorpionismis a health hazard for children in Ecuador and emphasizes the need to supply effective antivenomsagainst local species, which are not currently available. The genetic affinity of the Ecuadorian specimens with T. obscurus may underlay toxinological, clinical, and venom antigenic relationships among Amazonian scorpionsthat deserves further exploration for designing therapeutic strategies to treat scorpionismin the region.