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Writer's pictureFibonacciMD
Nov 6

Mauve Stinger Jellyfish (Pelagia noctiluca) Envenomation

Mauve stinger jellyfish are making waves in 2024.

This year, there have been increased sightings and stinging victims of mauve stinger jelly fish in Britain and France. Two years ago there were a large number sighted in Mid-Atlantic U.S. waters. These jellyfish, typically found in warmer waters, have been pushed further north due to unusual weather patterns. Learn about their sting symptoms, treatment options, and preventive measures.

InBrief

mauve stinger jellyfish

In late summer and fall of 2024, some areas of Europe were inundated with mauve stinger jellyfish sightings (also known as the purple-striped jellyfish or Pelagia noctiluca).  In September, 120 swimmers in a swim challenge event off the coast of the Isles of Scilly, in southwest Britain, ran into two swarms of mauve stinger jellyfish with most of the swimmers being stung.[1]  In October, tens of thousands of mauve stingers washed up on beaches in South Finistère, France.  It was thought that tropical storms had brought them further north than normal.[2]  In late August and early September 2022, there were numerous mauve stinger jellyfish, sightings and stings in Long Island and the New Jersey Shore in the U.S.[3,4]  These jellyfish are typically seen offshore and rarely found on the Northeastern U.S. coastline.  Weather and tide conditions were thought to be responsible.[4]  The mauve stinger jellyfish is most commonly found in the Mediterranean Sea but has been seen in other costal parts of Europe, as well as off the California coast.[5]


anatomy of a jellyfish

Jellyfish anatomy [6]

Mauve Stinger Jellyfish Stings

Mauve stinger jellyfish are typically 1 to 5 inches in diameter and are colored pink, mauve or light brown with a phosphorescent bell.  The nematocysts (the stinging cells of a jellyfish) are on the tentacles, the oral arms, and what is somewhat unusual for a jellyfish, on the surface of the bell.  Envenomation can occur from contact with either alive or dead mauve stinger jellyfish.  Typically, the stings are usually limited to the skin surface and cause only erythematous (reddish), edematous (swollen), and vesicular (blistering) lesions, with localized pain that can last for one to two weeks. Systemic complications or cutaneous infections are rare.  The skin lesions can be circular or irregularly shaped and scarring and hyperpigmentation may occur after healing.  The venom is also able to cause severe generalized allergic reactions.  Studies have revealed that most stings produce localized skin reactions, but a small percentage will have more serious systemic symptoms.  There are no reports of fatalities, but there is a case report of Guillain-Barre syndrome following envenomation.[7]  A relapse of the skin rash some years later may occur if re-stung by another mauve stinger jellyfish and has also been reported in some individuals who had no further contact with the jellyfish.  There may be some cross reactivity between mauve stinger jellyfish venom and Portuguese man o’war venom which can stimulate an allergic reaction.[5]



mauve jellfish sting on a finger

mauve jellyfish sting on forehead

Mauve Stinger Jellyfish Stings[8,9]

Treatment

The treatment of all jellyfish stings is controversial and the scientific literature in some cases is inconclusive or conflicting.  For some species vinegar (acetic acid) is recommended while in others baking soda slurry (sodium bicarbonate) is the recommended method to inactivate the nematocytes.  For some jellyfish stings hot water is recommended as initial therapy while in other species ice packs are suggested.[10]


Vinegar (acetic acid) is no longer recommended by the U.S. Red Cross for most jellyfish stings in U.S. waters, as there have been some studies that showed increased release of venom with its use.[11]  Several studies found vinegar increased nematocyst discharge in mauve stinger envenomations but seawater did not.[12,13]  However, an in vitro study (a study done in the laboratory) conversely found that vinegar did reduce nematocyst discharge.[14].  Sodium bicarbonate or baking soda is recommended for some jellyfish envenomations, such as for the sea nettle.  However, it has been found to increase nematocyst discharge in mauve purple jellyfish.[13]  Although there are conflicting recommendations, use of alkaline or acidic solutions may possibly cause a worsening of the envenomation in mauve stinger jellyfish stings and based on available literature probably should be avoided.[5]


It has been reported that 1% lidocaine, 70% ethanol, and 20% ammonia in vitro reduced nematocyst discharge[14], but as is not atypical another study found that ammonia activated the nematocysts.[13]  Used alone, topical lidocaine has been found in several mauve stinger studies to inactivate the nematocysts.[13,14]  It has also been found that calcium ions may be an important part of nematocyst activation and gadolinium which blocks cellular calcium channels was found to block nematocyst discharge in one study, but had no effect in another one.[5,13,15]


Though there are conflicting data and recommendations, the general recommendation for local care of mauve stinger jellyfish stings is first washing the area with seawater.  As removing the attached nematocyst may cause increased envenomation, any adherent jellyfish parts should gently be removed with gloves or a tweezer after sea water washing.[10,11]  They can also be scraped off with a seashell,[11] but scraping has been shown to potentially increase nematocyst discharge in some jellyfish species.[10]  If gloves are not available, adherent tentacles may be removed with bare fingers, which may only cause relatively harmless prickling, due to the thick palmar skin, but this is not a first choice.[16,17]  Topical lidocaine is recommended as an option in jellyfish stings by the Red Cross to reduce pain[11] and has been found in several mauve stinger studies to inactivate the nematocysts[13,14], so that can be one treatment option prior to removing the attached jellyfish parts.  The maximal recommended lidocaine dose should not be exceeded to avoid toxicity.


There has been some controversy about whether to use heat or ice packs as initial therapy after a jellyfish sting after the nematocysts have been removed.  In Australia, icepacks are recommended for tropical jellyfish stings and heat for non-tropical ones.[17]  As heat can inactivate jellyfish venom, which can decrease pain, the U.S Red Cross guidelines advise applying hot water or a hot pack between approximately 106-113° F (41-45o C) or as hot as tolerated (not scalding), for 20 minutes or until pain is relieved.[11]


mauve jellyfish

Mauve Stinger Jellyfish


Over-the-counter medication is generally adequate for treating pain.  Medical treatment, including possible hospitalization, may be needed for more severe reactions.  For all jellyfish stings, a tetanus booster is recommended if not up to date.  Prophylactic antibiotics are typically not necessary.  Antihistamines can be used for urticaria or allergic-type symptoms.[18]


There have been some studies using proprietary formulations to treat purple mauve stinger jellyfish stings, but one positive study authored by manufacturer employees, was unblinded and had no control group.[8]  The other was an in vitro study which found 10% lidocaine and some compounds used in cosmetics also work as inhibitors of nematocyst discharge.  It was thought that due to its viscous consistency one of the compounds, butylene glycol, wraps around the tentacle to act as a physical barrier.[13]


mauve jellyfish

Prevention

Prevention of stings can be achieved by avoiding swimming in jellyfish-infested waters, or use of a Lycra whole body stinger suit.[16]  A repellent cream of octyl methoxycinnamate and zinc oxide, sold commercially in some countries has been demonstrated to reduce the severity of jellyfish stings as well as providing sunburn protection.[16]  Another commercial jellyfish sting inhibitor and sunblock, that contains octinoxate, titanium dioxide and multiple other ingredients has also been demonstrated to reduce sting severity from some species.[16,19,20]


Conclusions

Mauve stinger jellyfish stings are generally painful but not life threatening.  This year they were seen in increased numbers in some areas of Europe and previously have been found in New Jersey and New York State coastal waters.  The literature, as is typical with jellyfish research, is sometimes contradictory.  Avoidance of jellyfish when they are seen in the water is the best advice, but once stung, washing with seawater and gentle removal of attached parts of the jellyfish is recommended.  Topical lidocaine may reduce pain and inactivate nematocysts.  Immersion of the affected area, showering in warm water, or using hot packs to try to deactivate the venom appears to be a reasonable recommendation.  Acid and alkali solutions have in some studies shown to worsen the venom discharge from nematocysts and are probably best avoided.  Other products that have been tested may have some benefit, but the studies were either in vitro or were not of sufficient scientific quality.



 



Here is another article on Jellyfish Stings .


 


References

Initially published Sept 2022.



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