Skin Disorders in Elderly Persons: Scabies

A number of factors heighten the risk of parasitic infections in elderly persons, who often live in communal settings (eg, nursing homes), where they are more likely to encounter parasites, such as the scabies mite. Debilitated patients are particularly susceptible to infestation and are thus at increased risk for the development of crusted, or Norwegian, scabies.

Here I describe and illustrate the manifestations of scabies in older adults.

DIAGNOSIS

Scabies is caused by infestation with Sarcoptes scabiei var hominis. It occurs worldwide and is highly contagious.

Figure 1

Figure 2

Figure 3

Scabies manifests as papules, pustules, burrows, nodules and, occasionally, urticarial papules and plaques. It can resemble eczema and psoriasis. Lesions are commonly found on the wrists, finger webs (Figure 1), antecubital fossae, axillae, areolae, periumbilical region, and genitals, including the penis (Figure 2). Most patients with scabies experience severe pruritus.

A subset of patients have Norwegian scabies (Figure 3).These patients, who are usually debilitated or immunocompromised, experience little or no pruritus and therefore do not scratch. As a result, hundreds to millions of mites are free to multiply and to infest the skin; the infestation manifests as confluent crusted plaques topped by thick hyperkeratotic scales.

Diagnosis of scabies is based on the patient history, physical examination results, and demonstration of mites, eggs, or scybala (black or brown football-shaped masses of feces of scabies mites) on microscopic examination.