OVERVIEW

What is mite dermatitis?

Mite dermatitis, commonly known as "grain itch," refers to an acute dermatitis characterized by erythema, rashes, and significant itching caused by mite bites or contact with their secretions.

Is mite dermatitis common?

Yes, it is common and can affect people of all ages. However, it most frequently occurs among farmers, workers handling crops or agricultural products, outdoor laborers, and hikers. People who frequently sleep on straw mats may also occasionally develop it.

Is mite dermatitis the same as scabies?

Not exactly.

Scabies specifically refers to a contagious skin disease caused by the scabies mite. It is more prevalent in winter and typically affects areas with thin, delicate skin, such as the armpits, groin, and finger webs. Scabies occurs when the mites burrow into the skin's stratum corneum, secreting toxins and excreting waste, which damage the skin and trigger an allergic reaction, leading to rashes.

The rashes are usually papules, either skin-colored or light red, and are accompanied by intense itching, especially at night. The two conditions can be distinguished by the type of rash and microscopic identification of the mite.

SYMPTOMS

What are the manifestations of mite dermatitis?

• It commonly occurs in warm and humid summer and autumn seasons. The rash mostly appears on exposed skin, and in severe cases, it may affect the entire body, particularly the neck, trunk, and limbs.

• The types of rashes include erythema, maculopapules, papulovesicles, urticarial papules, blisters, and ecchymosis. Sometimes, tiny needle-sized bite marks can be seen at the center of the rash. It is accompanied by intense itching, so in addition to the rash itself, scratch marks from the patient's scratching may also be visible.

• In patients with severe allergic reactions, systemic symptoms such as fever, headache, fatigue, and joint pain may occur alongside the skin rash. In rare cases, asthma may be triggered, and even kidney damage leading to proteinuria.

Can mite dermatitis heal on its own?

Mite dermatitis usually occurs after mites come into contact with the skin. These mites do not parasitize humans, so the itching gradually subsides and disappears within a few days. The rash typically resolves within 1–2 weeks, though occasionally it may persist for several weeks.

Does mite dermatitis leave any sequelae?

Generally, there are no sequelae. After the rash subsides, there may be temporary hyperpigmentation, but usually no scars remain. However, if severe skin damage occurs due to scratching or secondary bacterial infection, deeper and larger wounds may leave scars.

CAUSES

What causes mite dermatitis?

It is caused by mite bites and allergic reactions triggered by their secretions irritating the skin. Mites are small arachnids that often parasitize animals and plants. There are hundreds of thousands of mite species, including grain mites, chiggers, bird mites, rat mites, flour mites, and lice mites, which can lead to mite dermatitis.

DIAGNOSIS

How is mite dermatitis diagnosed?

The diagnosis of mite dermatitis is primarily based on a history of exposure, such as recent contact with crops, agricultural products, or outdoor activities involving bare skin, along with the appearance of characteristic rashes. After excluding other conditions, a diagnosis can usually be made.

What tests are needed for mite dermatitis? Why are these tests performed?

For confirmation, mites can be collected from the rash using adhesive tape and directly observed under an optical microscope. A blood test (complete blood count) may also reveal elevated eosinophils, though this finding is nonspecific, as it can occur in parasitic infections or allergic reactions.

What conditions should mite dermatitis be differentiated from?

Mite dermatitis should be distinguished from scabies, chickenpox, allergic contact dermatitis, pemphigus, and dermatitis caused by bites from other arthropods (such as lice or fleas).

TREATMENT

Which department should I visit for mite dermatitis?

Dermatology.

Does mite dermatitis require hospitalization?

Usually not.

How is mite dermatitis treated?

• Apply 1%–2% menthol, calamine lotion with phenol, or 5% camphor ethanol to the rash to relieve symptoms.

• For widespread rashes or severe itching, topical corticosteroid creams such as fluocinonide or dexamethasone can be used, along with oral antihistamines like promethazine, chlorpheniramine, or loratadine.

• If the rash becomes infected, topical antibiotic ointments can be applied.

DIET & LIFESTYLE

What should patients with mite dermatitis pay attention to in their diet?

There are no particularly prohibited foods, but try to minimize spicy, irritating foods and allergenic foods.

What should patients with mite dermatitis pay attention to in daily life?

• Avoid vigorous scratching when itching occurs to prevent skin damage from worsening and bacterial infections.

• Avoid washing rashes with excessively hot water.

• Keep the affected area dry.

Does mite dermatitis require follow-up visits?

Generally not necessary. It is considered cured once symptoms disappear and the rash subsides. Prevention measures should be taken to avoid re-exposure to the causative agents.

PREVENTION

Can Mite Dermatitis Be Prevented? How to Prevent It?

Mite dermatitis can be prevented.

• When handling crops, agricultural products, or engaging in outdoor activities, take personal protective measures by minimizing exposed skin and applying insect repellents containing aromatic oils (such as tea tree oil or lemongrass oil) to clothing and exposed skin. After activities, wash surface clothing with boiling water or treat them with pyrethroid insecticides to eliminate mites.

• Ensure proper ventilation and dryness in living spaces, warehouses, and grain stacks. Sun exposure and insecticide sprays can also kill mites.