Blister beetle dermatitis

A skin condition caused by contact with blister beetles

Classification
External resources

Blister beetle dermatitis is a skin condition that occurs when the skin comes into contact with certain species of blister beetles. These beetles secrete a chemical called cantharidin, which can cause irritation and blistering of the skin.

Overview

Blister beetles belong to the family Meloidae, and there are over 7,500 species worldwide. They are commonly found in areas with abundant vegetation, as they feed on plants. The beetles are known for their ability to produce cantharidin, a potent blistering agent that serves as a defense mechanism against predators.

Pathophysiology

The primary irritant in blister beetle dermatitis is cantharidin. When a blister beetle is crushed against the skin, cantharidin is released and absorbed into the epidermis. This leads to the formation of blisters, which are similar in appearance to those caused by burns. The blisters are typically painless but can be accompanied by itching and redness.

Clinical Presentation

The symptoms of blister beetle dermatitis usually appear within a few hours of contact with the beetle. The affected area may show:

• Erythema (redness)
• Vesicles or bullae (blisters)
• Pruritus (itching)
• Mild pain or discomfort

The blisters can vary in size and may coalesce to form larger bullae. In most cases, the condition is self-limiting and resolves within a week without scarring.

Diagnosis

Diagnosis of blister beetle dermatitis is primarily clinical, based on the characteristic appearance of the lesions and a history of exposure to blister beetles. In some cases, a skin biopsy may be performed to rule out other conditions.

Treatment

Treatment of blister beetle dermatitis is generally supportive. Recommendations include:

• Washing the affected area with soap and water to remove any remaining cantharidin
• Applying cool compresses to reduce inflammation
• Using topical corticosteroids to alleviate itching and redness
• Avoiding scratching to prevent secondary infection

In severe cases, oral antihistamines or systemic corticosteroids may be prescribed.

Prevention

Preventive measures include:

• Avoiding areas where blister beetles are known to inhabit
• Wearing protective clothing when working in gardens or fields
• Being cautious when handling plants that may harbor blister beetles

Related pages

• Dermatitis
• Cantharidin
• Meloidae
• Skin conditions