Aquatic Antagonists: Lionfish (Pterois volitans)

The lionfish (Pterois volitans) is a member of the Scorpaenidae family of venomous fish.^1-3 Lionfish are an invasive species originally from the Indian and Pacific oceans and the Red Sea that now are widely found throughout tropical and temperate oceans in both hemispheres. They are a popular aquarium fish and were inadvertently introduced in the Atlantic Ocean in South Florida during the late 1980s to early 1990s.^2,4 Since then, lionfish have spread into reef systems throughout the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico in rapidly growing numbers, and they are now fo und all along the southeastern coast of the United States.⁵

Characteristics

Lionfish are brightly colored with red or maroon and white stripes, tentacles above the eyes and mouth, fan-shaped pectoral fins, and spines that deliver an especially painful venomous sting that often results in edema (Figure 1). They have 12 dorsal spines, 2 pelvic spines, and 3 anal spines.

Figure 1. Lionfish (Pterois volitans).

Symptoms of Envenomation

As lionfish continue to spread to popular areas of the southeast Atlantic Ocean and Caribbean Sea, the chances of human contact with lionfish have increased. Lionfish stings are now the second most common marine envenomation injury after those caused by stingrays.⁴ Lionfish stings usually occur on the hands, fingers, or forearms during handling of the fish in ocean waters or in maintenance of aquariums. The mechanism of the venom apparatus is similar for all venomous fish. The spines have surrounding integumentary sheaths containing venom that rupture and inject venom when they penetrate the skin.⁶ The venom is a heat-labile neuromuscular toxin that causes edema (Figure 2), plasma extravasation, and thrombotic skin lesions.⁷

Figure 2. Edema of the right hand from a lionfish sting.

Wounds are classified into 3 categories: grade I consists of local erythema/ecchymosis, grade II involves vesicle or blister formation, and grade III denotes wounds that develop local necrosis.⁸ The sting causes immediate and severe throbbing pain, often described as excruciating or rated 10/10 on a basic pain scale, typically radiating up the affected limb. Puncture sites may bleed and often have associated redness and swelling. Pain may last up to 24 hours. Occasionally, foreign material may be left in the wound requiring removal. There also is a chance of secondary infection at the wound site, and severe envenomation can lead to local tissue necrosis.⁸ Systemic effects can occur in some cases, including nausea, vomiting, sweating, headache, dizziness, disorientation, palpitations, and even syncope.⁹ However, to our knowledge there are no documented cases of human death from a lionfish sting. Anaphylactic reactions are possible and require immediate treatment.⁶

A study conducted in the French West Indies evaluated 117 patients with lionfish envenomation and found that victims experienced severe pain and local edema (100%), paresthesia (90%), abdominal cramps (62%), extensive edema (53%), tachycardia (34%), skin rash (32%), gastrointestinal tract symptoms (28%), syncope (27%), transient weakness (24%), hypertension (21%), hypotension (18%), and hyperthermia (9%).⁹ Complications included local infection (18%) such as skin abscess (5%), skin necrosis (3%), and septic arthritis (2%). Twenty-two percent of patients were hospitalized and 8% required surgery. Local infectious complications were more frequent in those with multiple stings (19%). The study concluded that lionfish now represent a major health threat in the West Indies.⁹ As lionfish numbers have grown, health care providers are seeing increasing numbers of envenomation cases in areas of the coastal southeastern United States and Caribbean associated with considerable morbidity. Providers in nonendemic areas also may see envenomation injuries due to the lionfish popularity in home aquariums.⁹