Jellyfish are marine invertebrates. They are divided into 4 groups: Hydrozoa (e.g., the Portuguese man-of-war), Scyphozoa (true jellyfish), Cubozoa (e.g., Chironex fleckeri or the sea wasp, considered the most toxic), and Anthozoa (sea anemones and corals).1 Jellyfish are the main cause of marine envenomation. Their tentacles have stinging cells, or nematocysts, which they use to capture prey and to defend themselves. These cells contain a capsule with a thread that injects the venom on contact with the prey. The toxicity of the jellyfish sting varies according to the species: most jellyfish stings cause a painful burning sensation but the symptoms are usually short-lasting. However, bathers are advised to leave the water immediately because of the risk of anaphylactic shock and drowning.

We report the case of a 46-year-old woman with no relevant personal history who presented with a skin lesion on the right leg that had appeared 24hours earlier after bathing in the sea. The patient stated that the symptoms had begun as a sharp burning pain and within minutes the signs of inflammation had appeared. She came to the clinic because the symptoms were progressively worsening.

Physical examination revealed confluent erythematous papules in the shape of a jellyfish and a slight inflammation of the surrounding and underlying tissue (Fig. 1). The rest of the physical examination was normal. With an initial diagnosis of uncomplicated jellyfish sting, moderately potent corticosteroid cream and oral antihistamines were prescribed. However, the inflammation continued to progress until it caused secondary cellulitis covering almost the entire leg, making it necessary to prescribe systemic antibiotics and anti-inflammatory drugs. After 15 days the inflammation had resolved, leaving a slight residual hyperpigmentation that disappeared spontaneously over the following months.

Figure 1.

Inflammatory plaque on the leg in the shape of the jellyfish that caused the sting.

(0.07MB).

Reactions that occur after jellyfish envenomation are divided into 3 groups: immediate allergic reactions, immediate toxic reactions, and delayed allergic reactions.2 Death from stinging occurs through a hypersensitivity mechanism or through the effect of several toxins on the cardiovascular or respiratory systems or on the liver.3

Immediate local reactions are characterized by burning and itching of varying intensity according to the species of jellyfish that caused the sting. Involvement of surrounding soft tissue is common. The disease frequently presents as whiplash-like erythematous papules and papulovesicular lesions.

Vascular reactions (ischemia from vasospasm and thrombophlebitis of the underlying vessels) and regional lymph node reactions (inflammation of locoregional lymph nodes) have also been reported.

Other less commonly reported reactions include angioedema, recurrent reactions, contact dermatitis, and papular urticaria.

Delayed and persistent reactions, though little known, are not uncommon.4,5

Medical treatment depends on the type of reaction. Patients with uncomplicated skin reactions are treated symptomatically with topical corticosteroids and oral antihistamines and show a good response in a few days.

The most important advice for the first-aid management of jellyfish envenomation is to take measures to avoid release of the venom toxins: to wash the area with sea water rather than fresh water, to apply ice in packs rather than directly, to avoid rubbing the affected area, and to avoid applying urine or alcoholic drinks, which can change the pH and activate the nematocysts. Depending on the species of jellyfish that causes the sting, it can be useful to apply vinegar, a 1:1 aqueous solution of sodium bicarbonate, or a saturated solution of magnesium sulfate in a solution of sodium chloride.

Jellyfish sting reactions are very common on the Spanish coast in summer. Therefore, although these reactions tend to be local and short-lasting, we consider it important to know how to deal with them and to be aware of the less common reactions in order to diagnose them correctly and provide early treatment.