Clinical Evidence Handbook A Publication of BMJ Publishing Group

Scabies PAUL JOHNSTONE, Blenheim House, Leeds, United Kingdom MARK STRONG, University of Sheffield, Sheffield, United Kingdom

This is one in a series of Scabies is an infestation of the skin by the • Although tested in randomized chapters excerpted from mite Sarcoptes scabiei. In adults, the most controlled trials (RCTs), oral ivermectin is the Clinical Evidence Handbook, published by common sites of infestation are the fingers not presently licensed for the treatment of the BMJ Publishing Group, and the wrists, although it may manifest in scabies in most countries. It is only avail- London, U.K. The medical older persons as a diffuse truncal eruption. able on a named patient basis in the United information contained herein is the most accurate • Scabies is a very common public health Kingdom. available at the date of problem. In many resource-poor settings, it Topical lindane use has been restricted publication. More updated is an endemic problem; whereas in indus- or is not available in many parts of the and comprehensive infor- trialized countries, it is most common in world owing to the mounting evidence mation on this topic may be available in future print institutionalized communities. for serious adverse effects. We have not editions of the Clinical Evi- • Topical permethrin seems highly effec- included it in this review. However, it may dence Handbook, as well tive at increasing clinical cure of scabies be the most effective treatment that is as online at http://www. within 28 days. locally available in some countries. Harms clinicalevidence.bmj.com (subscription required). Topical permethrin use has been associ- must be carefully weighed against benefits ated with isolated reports of serious adverse before it is used. This series is coordinated by Kenny Lin, MD, MPH, effects, including death. Associate Deputy Editor Topical crotamiton seems effective at Definition for AFP Online. increasing clinical cure of scabies at 28 days, Scabies is an infestation of the skin by the A collection of Clinical although it is less effective than topical mite S. scabiei. Typical sites of infestation are Evidence Handbook pub- permethrin. skin folds and flexor surfaces. In adults, the lished in AFP is available We found insufficient evidence to judge most common sites are between the fingers at http://www.aafp.org/ the effectiveness of topical benzyl benzoate, and on the wrists, although it may manifest afp/bmj. topical malathion, or topical sulfur com- in older persons as a diffuse truncal erup- CME This clinical content pounds for treating scabies. tion. In infants and children, the face, scalp, conforms to AAFP criteria for continuing medical Oral ivermectin seems more effective at palms, and soles are also often affected. education (CME). See increasing clinical cure of scabies compared Infection with the scabies mite causes dis- CME Quiz Questions on with placebo. It may be more effective at comfort and intense itching, particularly at page 869. increasing clinical cure compared with topi- night, with irritating papular or vesicular Author disclosure: Paul cal benzyl benzoate. However, it may be eruptions. The discomfort and itching can Johnstone and Mark less effective than topical permethrin in the be especially debilitating in immunocom- Strong declare they have no competing interests. short term. promised persons, such as those with HIV/ • There have been isolated reports of severe AIDS. adverse effects with oral ivermectin, includ- ing death and convulsion, but these are rare. Incidence and Prevalence • Observational data suggest that oral Scabies is a common public health problem. ivermectin may be effective in certain cir- In many resource-poor settings, scabies is an cumstances, such as when included in the endemic problem; whereas in industrialized treatment of hyperkeratotic crusted sca- countries, it is most common in institution- bies, in persons with concomitant human alized communities. Case studies suggest that immunodeficiency virus (HIV) infection, epidemic cycles occur every seven to 15 years, and when treating outbreaks in residential and that these partly reflect the population’s facilities. immune status.

November 15, 2015 ◆ Volume 92, Number 10 www.aafp.org/afp American Family Physician 919 Clinical Evidence Handbook

Etiology and Risk Factors are predisposed to infestation and have par- Scabies is particularly common where there ticularly high mite counts. Although not is social disruption, overcrowding with close based on evidence from randomized con- body contact, and limited access to water. trolled trials, treating family members and Young children, immobilized older persons, other close contacts at the same time as treat- persons with HIV/AIDS, and other medically ing the index case is advisable to minimize and immunologically compromised persons reinfection and further spread. Clothing and bed linen belonging to the index case should also be washed. Clinical Questions Prognosis What are the effects of topical treatments for scabies? Scabies is not life-threatening, but the severe, Beneficial Permethrin (topical) persistent itch and secondary infections may Likely to be Crotamiton (topical; less effective than topical be debilitating. Occasionally, crusted scabies beneficial permethrin) develops. This form of the disease is resistant Unknown Benzyl benzoate (topical) to routine treatment and can be a source of effectiveness Malathion (topical) continued reinfestation and spread to others. Sulfur compounds (topical) What are the effects of systemic treatments for scabies? SEARCH DATE: July 2013 Likely to be Ivermectin (oral; although tested in randomized Adapted with permission from Johnstone P, Strong M. beneficial controlled trials, it is not presently licensed for the Scabies. Clin Evid Handbook. June 2015:582-583. Visit treatment of scabies in most countries) http://www.clinicalevidence.bmj.com for full text and references. ■

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920 American Family Physician www.aafp.org/afp Volume 92, Number 10 ◆ November 15, 2015