The toxicity of Physalia physalis: systematic review and experimental study

Abstract

Introduction: Jellyfish poisonings are frequent in coastal areas of temperate latitudes. In Spain, the most
frequent and dangerous jellyfish is the Portuguese man-of-war or Physalia physalis. Although the clinical
manifestations of P. physalis envenomation are known, the acute management and complications are
controversial, with varying criteria about proper treatment.
Materials and methods: This paper presents a systematic review of those studies that have collected clinical
aspects of the sting of P. physalis, as well as an experimental study that evaluates the discharge capacity
of nematocysts under different conditions (heated seawater at 50°C, 4°C seawater, distilled water, 25%
commercial vinegar, distilled water, 25% commercial vinegar in seawater) as a proxy for envenomation
potential including in sea lice. Also, discharged and undischarged nematocyst count was performed in air-
-dried tentacles at different times after specimen collection.
Results: Acetic acid does not produce nematocyst discharge when diluted in seawater and warm seawater
is an optimal rinsing agent that dissolves the jellyfish mesoglea. Furthermore, the nematocysts detached
from the jellyfish body maintain toxic capacity for at least 120 days after the stranding of the organism.
Conclusions: Most controversy regarding the treatment of P. physalis envenomation is related to the lack
of proper species stratification or identification. In our sample, acetic acid does not elicit nematocyst discharge
by itself, but depending on the solvent. Both vinegar and hot seawater rinses are the best first-aid
treatments. A first aid protocol is proposed based on data from the review and the experimental study.