Am Fam Physician. 2009;79(12):1089-1090
Author disclosure: Nothing to disclose.
Scabies is an infestation of the skin by the mite Sarcoptes scabiei. In adults, the most common sites of infestation are the fingers and the wrists, although infection may manifest in older persons as a diffuse truncal eruption.
The estimated prevalence is 300 million cases worldwide, with most instances occurring in resource-poor countries.
Topical permethrin is highly effective at increasing clinical and parasitic cure of scabies within 28 days.
Topical lindane is also an effective treatment for scabies, although it has been withdrawn from the market in the United Kingdom.
Lindane and permethrin may be more likely to be related to rare severe adverse effects, such as death or convulsions, compared with other treatments, such as benzyl benzoate, crotamiton, or malathion.
Topical crotamiton successfully produces clinical or parasitic cure after 28 days, although it is less effective than permethrin.
We did not find sufficient evidence to judge the effectiveness of topical benzyl benzoate, topical malathion, or topical sulfur compounds for treating scabies.
Oral ivermectin seems effective at increasing clinical cure rates compared with placebo.
Observational data suggest that oral ivermectin may be effective when included in the treatment of hyperkeratotic crusted scabies, and in persons with concomitant human immunodeficiency virus (HIV).
| What are the effects of topical treatments for scabies? | |
| Beneficial | Crotamiton (topical; as effective as topical lindane, but less effective than topical permethrin) |
| Permethrin (topical) | |
| Trade-off between benefits and harms | Lindane (topical) |
| Unknown effectiveness | Benzyl benzoate (topical) |
| Malathion (topical) | |
| Sulfur compounds (topical) | |
| What are the effects of systemic treatments for scabies? | |
| Likely to be beneficial | Ivermectin (oral) |
Definition
Scabies is an infestation of the skin by the mite Sarcoptes scabiei. Typical sites of infestation are skin folds and flexor surfaces. In adults, the most common sites are between the fingers and on the wrists, although infection may manifest in older persons as a diffuse truncal eruption. In infants and children, the face, scalp, palms, and soles are also often affected. Infection with the scabies mite causes discomfort and intense itching, particularly at night, with irritating papular or vesicular eruptions. The discomfort and itching can be especially debilitating among immunocompromised persons, such as those with HIV or acquired immunodeficiency syndrome (AIDS).
Prevalence
Scabies is a common public health problem, with an estimated prevalence of 300 million cases worldwide. It mostly affects persons in resource-poor countries, where prevalence can exceed 50 percent. In industrialized countries, it is most common in institutionalized communities. Case studies suggest that epidemic cycles occur every seven to 15 years, and that these partly reflect the population's immune status.
Etiology
Scabies is particularly common in areas where there is social disruption, overcrowding with close body contact, and limited access to water. Young children, immobilized older persons, persons with HIV or AIDS, and other medically and immunologically compromised persons are predisposed to scabies infestation and have particularly high mite counts.
Prognosis
Scabies is not life threatening, but the severe, persistent itching and secondary infections may be debilitating. Occasionally, crusted scabies develops. This form of the disease is resistant to routine treatment, can be a source of continued reinfestation, and may spread to other persons.
editor's note: Benzyl benzoate is not available in the United States.