The Dangers of Scorpion Sting Allergy

Scorpions are found worldwide. While some assume them to be insects, they are actually arachnids closely related to spiders, mites, and ticks. Scorpions have the ability to kill their prey by injecting venom from a stinger located at the end of their tail. 

The common striped bark scorpion, Centruroides vittatus, is the type most frequently seen in the United States. It is responsible for thousands of stings every year, most of which are painful but relatively harmless. Few human deaths are known to have occurred recently in the U.S. as a result of a scorpion sting. 

Symptoms

The venom of scorpion is responsible for mild neurotoxic symptoms, including numbness and tingling throughout the body. However, the range and severity of symptoms a person may experience may not be caused by the neurotoxin itself.

As with certain stinging insects, such as honeybees and yellow jackets, scorpion stings are known ​to cause an allergic reaction in susceptible people irrespective of the neurotoxic effects. In some cases, the allergy may result in a potentially life-threatening reaction known as anaphylaxis. Symptoms may include:

• Hives
• Allergic rhinitis
• Asthma-like symptoms
• Facial swelling
• Nausea or vomiting
• Drooling
• Respiratory distress
• Increased or erratic heart rate
• A feeling of impending doom
• Coma
• Shock

Causes

Typically speaking, in order for an allergy to occur, a person must have been exposed to a substance (known as an allergen) which the body regards as abnormal. After the initial exposure, allergic antibodies are produced. When that person is later re-exposed to the allergen, the antibodies trigger an allergic reaction.

This suggests that a person with a scorpion allergy must have been previously stung, right? Not always. In some cases, the immune system will recognize proteins in one allergen as belonging to another and respond in the same manner. This is referred to as "cross-reactivity."

In the case of scorpions, the venom of the red imported fire ant (Solenopsis invicta) appears to be highly cross-reactive. This type of stinging ant is native to South America but has become a widespread health hazard in many parts of the southern U.S. 

Treatment

Acute allergic reactions from scorpion stings are treated in much the same way as any insect sting. For mild skin-only reactions, antihistamines may be used. In life-threatening systemic reactions, epinephrine is used.

Currently, there is no known cure for a scorpion allergy other than to avoid being stung. However, given the cross-reactivity between scorpion and fire ant venom, some have theorized that allergy shots using fire ant extract may prevent both allergies. This may be an appropriate option for persons at risk of anaphylaxis in areas where fire ants and/or scorpions are endemic.