Scabies in an Infant

A 6-week-old girl was brought to the office for evaluation of a rash. The mother reported that the infant also had been fussy and had not been eating well, but had had no fever and was otherwise fine.

On physical examination, the girl was noted to have a generalized papular rash that was worse on the trunk and in the axillae (A and B). The rest of the physical examination findings were unremarkable. The infant’s mother and grandmother also reported having an extremely pruritic rash in the web spaces of their hands.

The infant received a diagnosis of scabies infestation. After 2 weeks of treatment with a topical scabicide, her condition had improved markedly (C).

Scabies is a contagious skin condition caused by Sarcoptes scabiei, a tiny parasitic mite with a round body. Human scabies almost always is spread by way of person-to-person contact. The mites burrow into the epidermis, where they secrete proteases and feed on necrotic tissue.

The number of mites on an invested person generally is fewer than 100; however, infested persons who are immune deficient can develop severe, crusted lesions known as Norwegian scabies that cover large areas of the body and house hundreds or even thousands of mites and mite ova.

Affected children become symptomatic approximately 4 to 6 weeks after the initial infestation. The associated rash is characterized by burrows and an erythematous papular eruption. The lesions also may be nodular, especially in infants.

Scabies mites prefer warmer sites, such as areas covered by jewelry (eg, the wrist, between the fingers), the beltline, around the nipples, and on the penis. In infants and children, the entire body can be affected, including the palms, soles, and scalp. In adults, the back, scalp, and usually neck are spared.

Diagnosis is based on clinical presentation and history, as well as potassium hydroxide testing of scrapings from a lesion. The management is 5% permethrin cream or oral ivermectin.