Cochrane Review: Interventions for treating scabies

Abstract

BackgroundScabies is an intensely itchy parasitic infection of the skin caused by the Sarcoptes scabiei mite. It is a common public health problem with an estimated global prevalence of 300 million cases. Serious adverse effects have been reported for some drugs used to treat scabies.ObjectivesTo evaluate topical and systemic drugs for treating scabies.Search strategyIn June 2010, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2010, Issue 2), MEDLINE, EMBASE, LILACS, and INDMED. In August 2010, we also searched the grey literature and sources for registered trials. We also checked the reference lists of retrieved studies.Selection criteriaRandomized controlled trials of drug treatments for scabies.Data collection and analysisTwo authors independently assessed trial quality and extracted data. Results were presented as risk ratios with 95% confidence intervals and data combined where appropriate.Main resultsTwenty‐two small trials involving 2676 people were included. One trial was placebo controlled, 18 compared two or more drug treatments, three compared treatment regimens, and one compared different drug vehicles.Fewer treatment failures occurred by day seven with oral ivermectin compared with placebo in one small trial (55 participants). Topical permethrin appeared more effective than oral ivermectin (140 participants, 2 trials), topical crotamiton (194 participants, 2 trials), and topical lindane (753 participants, 5 trials). Permethrin also appeared more effective in reducing itch persistence than either crotamiton (94 participants, 1 trial) or lindane (490 participants, 2 trials). No difference was detected between permethrin (a synthetic pyrethroid) and a natural pyrethrin‐based topical treatment (40 participants, 1 trial), and between permethrin and benzyl benzoate (53 participants, 1 trial), however both these trials were small.No significant difference was detected in the number of treatment failures between crotamiton and lindane (100 participants, 1 trial), lindane and sulfur (68 participants, 1 trial), benzyl benzoate and sulfur (158 participants, 1 trial), and benzyl benzoate and natural synergized pyrethrins (240 participants, 1 trial); all were topical treatments. No trials of malathion were identified.No serious adverse events were reported. A number of trials reported skin reactions in participants randomized to topical treatments. There were occasional reports of headache, abdominal pain, diarrhoea, vomiting, and hypotension.Authors' conclusionsTopical permethrin appears to be the most effective treatment for scabies. Ivermectin appears to be an effective oral treatment. More research is needed on the effectiveness of malathion, particularly when compared to permethrin, and on the management of scabies in an institutional setting and at a community level.Plain Language SummaryInterventions for treating scabiesScabies is a parasitic infection of the skin. It occurs throughout the world, but is particularly problematic in areas of poor sanitation, overcrowding, and social disruption, and is endemic in many resource‐poor countries. The global prevalence of scabies is estimated at 300 million cases, but the level of infection varies between countries and communities. The female mite burrows into the skin to lay eggs which then hatch out and multiply. The infection can spread from person to person via direct skin contact, including sexual contact. It causes intense itching with eruptions on the skin. Various drugs have been developed to treat scabies, and herbal and traditional medicines are also used. The review of trials attempted to cover all these. The authors identified 22 small trials involving 2676 people, with 19 of the trials taking place in resource‐poor countries. Permethrin appeared to be the most effective topical treatment for scabies, and ivermectin appeared to be an effective oral treatment. However, ivermectin is unlicensed for this indication in many countries. Adverse events such as rash, vomiting, and abdominal pain were reported, but the trials were too small to properly assess serious but rare potential adverse effects. No trials of herbal or traditional medicines were identified for inclusion.

Impetigo and scabies – Disease burden and modern treatment strategies

“…47 The efficacy of oral ivermectin is superior to placebo and topical lindane whilst trials comparing oral ivermectin to topical benzyl benzoate have demonstrated mixed results. 49,54 In the Cochrane review of scabies therapies, topical permethrin was found to be superior to oral ivermectin although the length of follow up in included trials ranged from 1 to 2 weeks only. 49 Although ivermectin is an effective and well-tolerated agent in the treatment of scabies there remain some limitations to its use.…”

“…20 Certainly comparison between studies examining prevalence and treatment outcomes is hindered by the lack of consensus criteria for the diagnosis of scabies. 48,49 Further research in designing simple and accurate diagnostic tests for scabies is ongoing.…”

“…46,54 The application of topical scabies therapies can result in skin reactions and tolerability may be further reduced in humid tropical climates. 49 Ivermectin is an oral scabicide which was previously reserved for cases of scabies refractory to topical therapy but is increasingly seen as a useful agent for both individual and community based treatment. 55 As ivermectin is not ovicidal a second dose is recommended 8e15 days following the initial dose to prevent recrudescence.…”

“…The distribution of infestation is different in infants with involvement of the palms, soles and scalp. 49 Scabies infestation is associated with significant complications related to secondary infection with bacteria. Bacterial infection, particularly with S. pyogenes and S. aureus, is a well-recognised complication of scabies infestation.…”

“…In a Cochrane review of randomised control trials comparing scabies therapies, permethrin was found to be the most effective topical therapy (superior to lindane and crotamiton). 49 Benzyl benzoate is another effective topical therapy that is preferred in some resource-limited settings due to the relatively high cost of permethrin, but is less well tolerated. 46,54 The application of topical scabies therapies can result in skin reactions and tolerability may be further reduced in humid tropical climates.…”