Freshwater jellyfish in northeastern Argentina: a risk to human health

Abstract

Background: Although cnidarians are mostly marine organisms, the occurrence of freshwater jellyfish frequently arouses the interest of ecologists, due to their sudden and unusual appearances in natural and artificial water bodies around the world. Methods: This study describes a series of cases compatible with cnidarian envenomation that occurred coinci- dentally in time and space with the presence of Craspedacusta sowerbii Lankester, 1880 jellyfish in the province of Misiones (El Saltito stream) in January 2022. A year later, its presence was confirmed in another watercourse of this province (Cazador stream). Based on these findings, its possible toxicological consequences in humans were evaluated by characterizing the jellyfish extract using sodium dodecyl sulfate-polyacrylamide gel electrophore- sis and enzymatic/toxic activities. Results: We revealed the presence of proteolytic enzymes and cytolytic toxin(s), which—by means of activating the inflammatory cascade—could explain the stinging skin lesions observed in the suspected cases described. Conclusions: In addition to recording for the first time the occurrence of this cnidarian in northeastern Argentina, this work provides, for the first time, a toxinological explanation for the clinical observations after contact with the most widespread freshwater jellyfish species in the world, giving support to health professionals in the diagnosis and management of such accidents/envenomation.