LIONFISH STINGS

Indo-Pacific lionfish (Pterois volitans) have invaded many popular scuba diving locations in the Atlantic and Caribbean. Aside from causing possible harm to swimmers and divers, this voracious predator can dramatically affect populations of native marine animals in the ecosystems to which they have been introduced.

Lionfish are venomous and belong to the Scorpaenidae family. These fish and those of the Synanceiidae family (such as Synanceia, or stonefish) comprise most of the existing venomous fish. Without putting life at risk, envenomations caused by scorpionfish and lionfish can cause significant symptoms due to the systemic action of their venoms.

Lionfish have spines that are covered by an epithelial sheath containing venom-producing glands in the grooves of the upper two-thirds of the long and slender spines. The dorsal fin has

12 or 13 rays or spines, the pelvic fin has two, and the anal fin has three. When the ray of the fin penetrates the victim’s skin, venom flows to the wound. Possible contact with various marine life occurs during diving, fishing and food handling. Even though most fish stings are benign, some lionfish stings require urgent medical treatment.

Puncture wounds by lionfish can cause pain lasting for several hours, rapid edema (swelling) and subcutaneous bleeding. Swelling typically clears in two to three days, while the tissue discolourations can last up to five days. In some cases swelling can become so severe that blood flow is compromised, possibly leading to tissue necrosis

(tissue death), which can be common in fingertips. A secondary complication is wound infections. Lionfish venom is not lethal to healthy humans, and we are not aware of any published reports of death.

Envenomations are rare even in areas where lionfish are common, but recognition of the fish is important to prevent injuries. In Cozumel, we have gathered six years of data encompassing 107 cases for which we recorded the following symptoms in order of frequency: pain, erythema (redness), edema, local heat, blisters, necrosis (dead tissue), nausea, vomiting, dyspnea, fever and muscular weakness.

Limb paralysis and cardiac failure are infrequently observed.

We have recorded only two complications from lionfish envenomations: one due to thermal burn (and later infection) when applying hot water to the sting area and one case of decompression sickness resulting from a diver reacting with a rapid ascent after being stung. The injuries we recorded did not pose risks of cardiovascular failure or death in our patients. The most important symptoms were the local inflammation and severe pain. We did not observe in our patients some signs and symptoms sometimes reported with lionfish envenomations; we recorded