Scabies (pediatric) in Infant/Neonate
Scabies is a parasitic infestation of the epidermis. It is caused by the obligate human parasite Sarcoptes scabiei var hominis and is transmitted via direct skin-to-skin contact and rarely by fomites. Scabies affects all ethnic groups and socioeconomic levels. It is most common in young children, and the highest prevalence is seen in children younger than 2 years. It is extremely contagious, spreading between individuals who share close contact or living spaces. Frequent outbreaks occur in schools, group homes, and orphanages where direct contact with infested individuals is common. The most common predisposing factors are overcrowding, poverty, poor nutrition, and being undomiciled. Other predisposing conditions include immunocompromised status, HIV infection, and severe intellectual or physical disability.
Symptoms and signs typically develop approximately 3 weeks after the primary infestation. The most common clinical manifestation of scabies in infants is the development of pustules, vesicles, and crusting. The palms and soles, fingers, face, and scalp are most heavily involved. Secondary impetigo and eczematization are also common. The primary symptom of infestation is pruritus, and in young infants who have not developed a coordinated itch response, this may manifest as rubbing the head against a caregiver, irritability, insomnia, and poor feeding.
Crusted scabies (formerly known as Norwegian scabies) is a variant of scabies characterized by profuse proliferation of mites within the epidermis, with subsequent widespread scaly, crusted, or hyperkeratotic papules and plaques. Pruritus may be severe but is usually minimal or absent. It is mainly seen in immunocompromised individuals.
B86 – Scabies
128869009 – Infestation by Sarcoptes scabiei var hominis
Differential Diagnosis & Pitfalls
- Infantile acropustulosis – Thought by many authors to be precipitated by scabies.
- Eosinophilic folliculitis of infancy – Extremely pruritic; scalp involvement may differentiate from scabies.
- Impetigo – Erythematous vesiculopustular lesions that rupture, forming the pathognomonic honey-colored crust. Lesions may involve the face, neck, and extremities. Scabies may sometimes be impetiginized, so a good history may distinguish primary versus secondary impetigo.
- Neonatal herpes – Discrete or grouped vesicles on an erythematous base, possibly with systemic symptoms. Tzanck smear from the vesicle reveals multinucleated giant cells.
- Congenital cutaneous candidiasis – Presents at birth, may affect the nails, and may be associated with placental lesions and inflammation. Potassium hydroxide (KOH) preparation of vesicular contents reveals yeast and pseudohyphae.
- Cutaneous candidiasis – Affects the intertriginous areas, especially the groin or neck, in the form of confluent erythematous patches with multiple, small satellite pustules. A KOH test from a pustular lesion reveals budding spores and pseudohyphae.
- Atopic dermatitis – Eczematous lesions with oozing on the face and flexural areas (cubital and popliteal fossa). Lichenification is seen in chronic dermatitis. Burrows are absent, and lesions are not seen in the web spaces.
- Papular urticaria – A hypersensitivity reaction to a variety of bites, such as mosquitoes, fleas, bedbugs, and mites. There may be a seasonal occurrence. Recurrent episodes of excoriated papular and urticarial lesions on the exposed parts of the extremities (extensor aspect) are the cardinal features. Absence of burrows and family history of itching differentiate this from scabies.