Differing Effects of Vinegar on <i>Pelagia noctiluca</i> (Cnidaria: Scyphozoa) and <i>Carybdea marsupialis</i> (Cnidaria: Cubozoa) Stings—Implications for First Aid Protocols

• Main Authors: Ainara Ballesteros, Macarena Marambio, Verónica Fuentes, Mridvika Narda, Andreu Santín, Josep-Maria Gili
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: Toxins
• Subjects: jellyfish; sting; first-aid; vinegar; seawater; nematocyst discharge
• Online Access: https://www.mdpi.com/2072-6651/13/8/509

The jellyfish species that inhabit the Mediterranean coastal waters are not lethal, but their stings can cause severe pain and systemic effects that pose a health risk to humans. Despite the frequent occurrence of jellyfish stings, currently no consensus exists among the scientific community regarding the most appropriate first-aid protocol. Over the years, several different rinse solutions have been proposed. Vinegar, or acetic acid, is one of the most established of these solutions, with efficacy data published. We investigated the effect of vinegar and seawater on the nematocyst discharge process in two species representative of the Mediterranean region: <i>Pelagia noctiluca</i> (Scyphozoa) and <i>Carybdea marsupialis</i> (Cubozoa), by means of (1) direct observation of nematocyst discharge on light microscopy (tentacle solution assay) and (2) quantification of hemolytic area (tentacle skin blood agarose assay). In both species, nematocyst discharge was not stimulated by seawater, which was classified as a neutral solution. In <i>P. noctiluca</i>, vinegar produced nematocyst discharge <i>per se</i>, but inhibited nematocyst discharge from <i>C. marsupialis</i>. These results suggest that the use of vinegar cannot be universally recommended. Whereas in case of a cubozoan <i>C. marsupialis</i> sting, the inhibitory effect of vinegar makes it the ideal rinse solution, in case of a scyphozoan <i>P. noctiluca</i> sting, vinegar application may be counterproductive, worsening the pain and discomfort of the stung area.