The family Scorpaenidae are saltwater fish that are mostly bottom dwellers noted for their ability to camouflage themselves and disappear into the environment. There are 30 genera and about 300 species, some 30 of which can envenomate humans. Although they once were considered an occupational hazard only to commercial fishing, increasing contact with these fish by scuba divers and home aquarists has increased the frequency of envenomations.
Mechanism of toxicity. Envenomation usually occurs when the fish is being handled or stepped on or when the aquarist has hands in the tank. The dorsal, anal, and pectoral fins are supported by spines that are connected to venom glands. The fish will erect its spines and jab the victim, causing release of venom (and often sloughing of the integumentary sheath of the spine into the wound). The venom of all these organisms is a heat-labile mixture that is not completely characterized.
Toxic dose. The dose of venom involved in any sting is variable. Interspecies difference in the severity of envenomation is generally the result of the relation between the venom gland and the spines.
Synanceja (Australian stonefish) have short, strong spines with the venom gland located near the tip; therefore, large doses of venom are delivered, and severe envenomation often results.
Pterois (lionfish, turkeyfish) have long delicate spines with poorly developed venom glands near the base of the spine and therefore are usually capable of delivering only small doses of venom.
Clinical presentation. Envenomation typically produces immediate onset of sharp, throbbing, intense, excruciating pain. In untreated cases, the intensity of pain peaks at 60–90 minutes, and the pain may persist for 1–2 days.
Systemic intoxication associated with stonefish envenomation can include the rapid onset of hypotension, tachycardia, cardiac arrhythmias, myocardial ischemia, syncope, diaphoresis, nausea, vomiting, abdominal cramping, dyspnea, pulmonary edema, cyanosis, headache, muscular weakness, and spasticity.
Local tissue effects include erythema, ecchymosis, and swelling. Infection may occur owing to retained portions of the integumentary sheath. Hyperalgesia, anesthesia, or paresthesias of the affected extremity may occur, and persistent neuropathy has been reported.
Diagnosis usually is based on a history of exposure, and the severity of envenomation is usually readily apparent.
Specific levels. There are no specific toxin levels available.
Other useful laboratory studies for severe intoxication include electrolytes, glucose, BUN, creatinine, creatine kinase (CK), urinalysis, ECG monitoring, and chest radiography. Soft-tissue radiographs of the sting site may occasionally demonstrate a retained integumentary sheath or other foreign material but should not be substituted for direct exploration of the wound when indicated.
Emergency and supportive measures
After severe stonefish envenomation:
Maintain an open airway and assist ventilation if needed (See Airway and Breathing). Administer supplemental oxygen.
Treat hypotension (See Hypotension) and arrhythmias (See QRS interval prolongation, Tachycardia, and Ventricular dysrhythmias) if they occur.
General wound care:
Clean the wound carefully and remove any visible integumentary sheath. Monitor wounds for development of infection.
Give tetanus prophylaxis if needed.
Specific drugs and antidotes. Immediately immerse ...