Scorpion Envenoming in Ecuador: District-Level Risk, Updated Scorpion Diversity, and Challenges for Treatment and Public Health

 

Scorpion Envenoming in Ecuador: District-Level Risk, Updated Scorpion Diversity, and Challenges for Treatment and Public Health

Abstract

This study assessed scorpion envenoming risk in Ecuador at provincial and district levels between 2017 and 2021, estimated national incidence and mortality rates, and identified the likely implicated taxa. Data were obtained from the Ministry of Public Health and aggregated by province and district, with incidence and mortality rates calculated per 100,000 inhabitants using annual population estimates. District-level risk was visualized with choropleth maps, and scorpion diversity and distribution were compiled from updated national inventories. A total of 1,514 scorpion stings were reported between 2017 and 2021. National incidence and mortality rates (per 100,000 inhabitants) averaged 1.75 and 0.02. Regional incidence was highest in the Amazonian region (16.81), followed by the coastal (1.39) and Andean highlands (0.66). Hyperendemic districts (≥95th percentile of risk) included Taisha and Tiwintza (Morona Santiago), Arajuno (Pastaza), Flavio Alfaro (Manabí), and La Concordia (Santo Domingo de los Tsáchilas). Mortality was highest in the Amazonian and piedmont coastal regions, with 10 deaths per region and an Amazonian rate of 0.44 per 100,000 inhabitants. These areas are inhabited by Tityus species from distinct morphological and toxinological groups, notably Tityus cf. rosenbergi in western Ecuador and Tityus cisandinus in Morona Santiago and Pastaza. Geographical variation in incidence and mortality likely reflects both the distribution of noxious taxa and population density. Despite high scorpion endemicity (79.2%), a national lethality rate of 1.32% that appears higher than reported in other countries where scorpionism is a public health concern, and the concentration of fatalities in children (75% in ages 1–9), Ecuador still depends on imported scorpion antivenoms, including that prepared against Centruroides species, which show low reactivity to Tityus toxins. These findings highlight the urgent need for preclinical neutralization studies to evaluate local antivenom efficacy and to investigate regional differences in clinical outcomes, to guide future adjustments to immunotherapy based on the biogeographic distribution of medically important Tityus species.

Borges, A., De Sousa, L., Borja-Cabrera, G. P., & Rivera, A. (2025). Scorpion Envenoming in Ecuador: District-Level Risk, Updated Scorpion Diversity, and Challenges for Treatment and Public Health. Acta Tropica, 107942. https://doi.org/10.1016/j.actatropica.2025.107942