Acarodermatitis

Definition & Etymology

Acarodermatitis is a form of dermatitis characterized by skin inflammation resulting from bites or infestation by mites of the order Acarina (from Greek akari, “mite” + derma, “skin” + -itis, “inflammation”). The condition is primarily a hypersensitivity reaction to the mite’s saliva, feces, or body parts. The clinical presentation, therefore, stems not from the physical trauma of the bite itself but from the host’s immune response to foreign antigens introduced by the arthropod.

Clinical Significance

Clinically, acarodermatitis is a common cause of intense pruritus (itching) and erythematous skin eruptions. The characteristic lesions are typically papules, vesicles, or wheals, which are often excoriated due to scratching. The location and pattern of the rash can provide diagnostic clues to the specific type of mite involved. Diagnosis relies heavily on the patient’s history of potential exposure (e.g., contact with animals, infested bedding, or outdoor activities) and the characteristic clinical findings. While microscopic identification of the causative agent from skin scrapings is definitive for certain conditions like scabies, it is often not feasible for other mite-related dermatoses.

Related Conditions

Acarodermatitis is a broad term that encompasses several specific conditions. The most well-known and clinically significant is scabies, caused by Sarcoptes scabiei. Other related conditions include chigger bites (trombiculosis), demodicosis (from Demodex mites), and dermatoses caused by animal mites that transiently infest humans, such as cheyletiellosis (“walking dandruff”) from pet mites, or dermatitis from bird and rodent mites. Differential diagnoses include other arthropod bites (e.g., fleas, bed bugs), allergic contact dermatitis, and atopic dermatitis.

Key Takeaways

• Acarodermatitis refers to any skin inflammation caused by an allergic reaction to mites, not a direct infection.
• The hallmark symptoms are intense itching (pruritus) and a papular or vesicular rash, which can lead to secondary bacterial infections from scratching.
• It is an umbrella term for various specific mite-induced conditions, with scabies being the most prominent example in humans.

Note: This content is for informational purposes only and does not substitute for professional medical advice. Always consult your doctor for diagnosis and treatment.