WILDERNESS & ENVIRONMENTAL MEDICINE, 27, 25–38 (2016)

ORIGINAL RESEARCH

Efﬁcacy of Topical Treatments for Chrysaora chinensis
Species: A Human Model in Comparison with an In
Vitro Model
Matthieu P. DeClerck, MD; Yvonne Bailey, MD; David Craig, MD; Michelle Lin, BA; Lauren J. Auerbach, BS;
Olivia Linney, BS; Doug E. Morrison, MS; Wyatt Patry, BS; Paul S. Auerbach, MD, MS
From the Division of Emergency Medicine, Department of Surgery, Stanford University School of Medicine, Stanford, CA (Drs CeClerck, Bailey,Craig, and P. Auerbach; Ms Lin; and Ms L. Auerbach); the Oregon Health and Science University School of Medicine, Portland, OR (Ms Linney);
the Department of Surgery, Stanford University School of Medicine, Stanford, CA (Mr Morrison); and the Division of Husbandry, Monterey Bay
Aquarium, Monterey, CA (Mr Patry).

Objectives.—This study sought to create a model for testing topical treatment of jellyﬁsh stings.
It sought to determine which treatments 1) stimulate/inhibit nematocyst discharge; 2) decrease pain; and3) decrease skin inﬂammation; it also sought to discover whether there is a clinical correlation between
stimulated nematocyst discharge observed in vitro to the pain and erythema experienced by humans
stung by a particular species of jellyﬁsh, C chinensis.
Methods.—Chrysaora chinensis stung 96 human subjects, who were then treated with isopropyl
alcohol, hot water, acetic acid, papain meat tenderizer, lidocaine, or sodium bicarbonate. Pain anderythema were measured. In a separate experiment, nematocysts were examined microscopically after
exposure to the same topical treatments used in the human experiment.
Results.—Forearms treated with papain showed decreased mean pain over the ﬁrst 30 minutes after
being stung, relative to placebo, although only by a small amount. The other topical treatments tested
did not reach statistical signiﬁcance. Sodium bicarbonate may reduce erythema after 30 minutes oftreatment; sodium bicarbonate and papain may reduce erythema at 60 minutes. The other topicaltreatments tested did not reach statistical signiﬁcance. Nematocyst discharge in vitro occurred whententacles of C chinensis were exposed to acetic acid or isopropyl alcohol. Sodium bicarbonate, papain,
heated water, and lidocaine did not induce nematocyst discharge.
Conclusions.—Papain-containing meat tenderizer used as a topical treatment for C chinensis stings
may decrease pain. Although there is published experimental support for the concept that in vitro
nematocyst discharge correlates with in vivo human pain perception, no deﬁnitive randomized
controlled trial, including ours, has yet provided incontrovertible evidence of this assertion. Despite
this study’s limitations, it presents a viable basis for future human studies looking at the efﬁcacy of
topical treatments for jellyﬁsh stings.

Introduction
Jellyﬁsh stings upon humans are worldwide occurrences,with an estimated 150 million people stung annually.1
Jellyﬁsh of the phylum Cnidaria envenom prey by using
stinging organelles (nematocysts) that are contained
within nematocytes lining the tentacles and mouth.
Nematocysts comprise a secretory organelle (cnida)with a capsule containing a coiled, barb-laden tubule
Corresponding author: Matthieu P. DeClerck, MD, 743 S. Mentor
Ave, Pasadena, CA 91106 (e-mail: mpdeclerck@gmail.com).

(nema), trigger (cnidocil), and venom. Envenomation
occurs upon mechanical or chemical stimulation of thecnidocil, which leads to injection of the nema into
the victim and venom release.2 A single jellyﬁsh
may carry millions of nematocysts. An individual
nematocyst can discharge its nema with a velocity of
2 m/s, corresponding to an acceleration of 40,000g,ensuring effective penetration of human skin andenvenomation.2,3There exist thousands of jellyﬁsh species, many ofwhich are dangerous to humans.3 The nematocysts andvenom of the majority of these species have not been not26
well characterized, but it is clear that variability exists innematocyst structure and venom composition. There areat least 30 morphological types of nematocysts.4
Similarly, clinical manifestations of jellyﬁsh stings vary
widely. Reactions range from minor local skin eruption
with pain (most common) to systemic toxicity and death.
Many jellyﬁsh venoms contain a dermonecrotic
component, which causes local skin inﬂammation andnecrosis.5 Although the exact mechanisms of systemic
toxicity have still not been completely elucidated,previous studies suggest that jellyﬁsh venoms containneurotoxic, cardiotoxic, and hemolytic components that
may lead to death from respiratory failure, cardiac
failure, or anaphylactic shock.2,5,6 The severity of ajellyﬁsh sting varies according to the species of jellyﬁsh,degree of envenomation, and age and baseline health ofthe victim.
Various recommendations exist in the medical and lay
literature regarding the most effective treatments forpeople who have experienced jellyﬁsh stings. Sometreatments seek to prevent the ﬁring of undischargednematocysts; others attempt to inactivate the injected
toxin or decrease inﬂammation. Anecdotal recommendations and prior studies have referenced a wide variety
of topical remedies, including such substances as humanurine, vinegar, isopropyl alcohol, distilled spirits, ammonia, bleach, acetone, sodium bicarbonate, lidocaine, meattenderizer, Coca-Cola, old wine, salt water, cold packs,
hot packs, hot water, and commercial products such as
Stingose or Stingaid.2–5,7–12
Many sources recommend a single treatment method
for all jellyﬁsh stings, but it is likely that no single
topical approach is effective for all known stinging
species. For example, studies showing that acetic acidinhibits nematocyst discharge in multiple species of
cubozoan jellyﬁsh have cemented the role of acetic acidin the acute treatment of stings by the deadly Chironex
ﬂeckeri.6,8 However, studies using other jellyﬁsh species
have found that acetic acid causes nematocyst discharge.4,6–8 Conﬂicting data regarding nematocyst discharge have even been found for two species ofPhysalia. For instance, some studies utilizing the genusPhysalia have observed nematocyst discharge afterapplication of acetic acid, whereas others have foundinhibition of discharge.7,9 Whether nematocyst discharge
observed during in vitro experimentation actually translates to clinical outcomes is unknown.
In our study, we set out to create a human model ofjellyﬁsh sting treatment that would allow for testing ofcommonly proposed topical remedies in a controlled,prospective, randomized, and blinded manner. The
human model was run in comparison with the in vitro
model to assess for any correlation between clinical

DeClerck et al
outcomes with nematocyst discharge triggered by topicaltreatments. This model would hopefully allow futurestudies to use the same or similar methodology.
The speciﬁc questions we sought to address were 1)
which treatments increase or decrease the number ofnematocysts discharged when viewed microscopically; 2)which treatments decrease pain in humans using a verbal
pain scale; 3) which treatments decrease the amount of skininﬂammation using an erythema index; and 4) whether
there is a clinically relevant correlation between stimulated
nematocyst discharge observed in vitro and the pain anderythema humans stung by a jellyﬁsh experienced.
Methods
JELLYFISH ACQUISITION
We used Chrysaora chinensis (Figure 1), a tropicaljellyﬁsh species indigenous to coastal waters in theAndaman, Java, and South China Seas. This species ofjellyﬁsh was chosen for its ready availability andstinging potential. The jellyﬁsh were supplied andmaintained by the jellyﬁsh husbandry team at theMonterey Bay Aquarium (MBA) in Monterey,California. C chinensis jellyﬁsh were shipped to theFigure 1. Live specimen of Chrysaora chinensis used for harvestingof tentacles for study. The jellyﬁsh were housed in saltwater aquariums
at the Monterey Bay Aquarium in California.

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