Scorpions-friend or foe?

Scorpion Envomenation

Disease description:
Scorpion venom toxicosis in the U.S. is due to the sting of Centruroides spp. which usually does not cause a medically significant problem ¹ except for an allergic type of reaction. In other parts of the world, especially tropical and subtropical countries, some scorpion species (example: Tityus) can result in death especially in sensitive individuals. ^2-4

Scorpions are arachnids with a long, slender body and a five-segmented tail that can be arched over the back. The tail ends in a bulb-like poison gland or stinger. Scorpions are found in many types of habitats in the U.S: desert flats, sand dunes, desert and mesic mountains, grasslands, pine forests, deciduous forests, and chaparral. They prefer moist cool hiding places and tend to hide during the day and become active at night. Centruroides sculpturatus is about 4 cm long with yellowish coloration, slender pincers, and a tubercle at the base of its stinger.

PATHOPHYSIOLOGY

Worldwide, scorpions range in size from 0.5 inch to 7.25 inches long (including the tail) depending on the species. Of 1,500 species of scorpions worldwide, only about 20 to 25 are regarded as dangerous. Scorpion venom contains protein neurotoxins that activate sodium channels depolarizing the presynaptic terminals causing excitatory neurotoxicity. Stings from dangerous species may cause disorientation, hypertension, paralysis, severe convulsions. Tachyarrhythmias and respiratory and cardiac failure can result in death. Parasympathetic signs could include hyperlacrimation, urination, defecation, and hypersalivation. Sympathetic signs could include skeletal muscle fasciculations, restlessness, hypermotility, and contortions.

CLINICAL SIGNS AND DIAGNOSIS OF CENTRUROIDES STINGS

Although Centruroides spp. can cause serious systemic signs (hypertension and CNS signs), most stings only cause local signs similar to that of a wasp sting: pain at sting site, hyperesthesia, itching, and local swelling. However, reaction to the bite may vary based on sensitivity of the individual.

Diagnosis is based on seeing a scorpion sting the patient and identifying the scorpion.