Control of scabies and secondary impetigo: optimising treatment effectiveness in endemic settings
Authors: Olivier Chosidow, Roderick J Hay
Journal: The Lancet Infectious Diseases (2019)

Scabies is more than a common parasitic skin disease1Chosidow O Clinical practices. Scabies.N Engl J Med. 2006; 354: 1718-1727Crossref PubMed Scopus (377) Google Scholar and health authorities in low-income and middle-income countries now recognise it as a public health issue. In 2017, WHO added scabies to the list of neglected tropical diseases for the following reasons: it is very common (point prevalence of up to 200 million),2GBD 2017 Disease and Injury Incidence and Prevalence CollaboratorsGlobal, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017.Lancet. 2018; 392: 1789-1858Summary Full Text Full Text PDF PubMed Scopus (6082) Google Scholar has a substantial global burden in disability-adjusted life-years,3Hay RJ Johns NE Williams HC et al.The global burden of skin disease in 2010: an analysis of the prevalence and impact of skin conditions.J Invest Dermatol. 2014; 134: 1527-1534Summary Full Text Full Text PDF PubMed Scopus (794) Google Scholar, 4Karimkhani C Colombara DV Drucker AM et al.The global burden of scabies: a cross-sectional analysis from the Global Burden of Disease Study 2015.Lancet Infect Dis. 2017; 17: 1247-1254Summary Full Text Full Text PDF PubMed Scopus (130) Google Scholar has notable psychosocial and economic effects caused by stigma and work disruption, and the major sleep disturbances and damage to the skin barrier caused by scratching. Sarcoptes scabiei also inhibits complement pathways, leading to streptococcal and staphyloccocal superinfection of the skin.5Swe PM Christian LD Lu HC Sriprakash KS Fischer K Complement inhibition by Sarcoptes scabiei protects Streptococcus pyogenes—an in vitro study to unravel the molecular mechanisms behind the poorly understood predilection of S. pyogenes to infect mite-induced skin lesions.PLoS Negl Trop Dis. 2017; 11: e0005437Crossref PubMed Scopus (33) Google Scholar Controlling secondary bacterial pyodermas caused by scabies is crucial. Patients in tropical areas with Staphylococcus aureus bacteraemia and scabies have a higher mortality than those without scabies;6Lynar S Currie BJ Baird R Scabies and mortality.Lancet Infect Dis. 2017; 17: 1234Summary Full Text Full Text PDF PubMed Scopus (24) Google Scholar but other life threatening infections such as cellulitis or necrotising soft tissue infection might occur, and impetigo might lead to haematuria or post-streptococcal glomerulonephritis and acute rheumatic fever or rheumatic heart disease.7Engelman D Kiang K Chosidow O et al.Toward the global control of human scabies: introducing the International Alliance for the Control of Scabies.PLoS Negl Trop Dis. 2013; 7: e2167Crossref PubMed Scopus (123) Google Scholar, 8Thornley S Marshall R Jarrett P Sundborn G Reynolds E Schofield G Scabies is strongly associated with acute rheumatic fever in a cohort study of Auckland children.J Paediatr Child Health. 2018; 54: 625-632Crossref PubMed Scopus (32) Google Scholar In The Lancet Infectious Diseases, Lucia Romani and colleagues9Romani L Marks M Sokana O et al.Efficacy of mass drug administration with ivermectin for control of scabies and impetigo, with coadministration of azithromycin: a single-arm community intervention trial.Lancet Infect Dis. 2019; (published online April 4.)http://dx.doi.org/10.1016/S1473-3099(18)30790-4Summary Full Text Full Text PDF PubMed Scopus (52) Google Scholar report on the efficacy of the coadministration of oral ivermectin and azithromycin for control of scabies and impetigo in the Choiseul Province of the Solomon Islands. Using the opportunity of a trachoma mass drug administration campaign in the general population, the investigators added ivermectin (or permethrin 5% cream) in a subgroup of the population using a single-arm intervention study design. Primary outcome data, published elsewhere,10Romani L Marks M Sokana O et al.Feasibility and safety of mass drug coadministration with azithromycin and ivermectin for the control of neglected tropical diseases: a single-arm intervention trial.Lancet Glob Health. 2018; 6: e1132-e1138Summary Full Text Full Text PDF PubMed Scopus (20) Google Scholar showed that combining ivermectin and azithromycin is safe and achievable. As a secondary outcome, the authors measured the prevalence of scabies and impetigo using a before-and-after design with two different sets of ten randomly selected villages (only four of the ten villages were actually visited twice, with change in prevalence assessed via a paired sensitivity analysis). A parallel relative reduction in prevalence was found for scabies (88%, 95% CI 76·5–99·3) and impetigo (74%, 63·4–84·7). And a comparison of outpatient attendance at government clinics across the province in the 3 months before and after mass drug administration showed that the number of people presenting with skin sores, boils, and abscesses decreased by 50·9% (95% CI 48·6–53·1).9Romani L Marks M Sokana O et al.Efficacy of mass drug administration with ivermectin for control of scabies and impetigo, with coadministration of azithromycin: a single-arm community intervention trial.Lancet Infect Dis. 2019; (published online April 4.)http://dx.doi.org/10.1016/S1473-3099(18)30790-4Summary Full Text Full Text PDF PubMed Scopus (52) Google Scholar Compared with interventions in individuals, a lot of data is now available in endemic or epidemic settings from mass drug administration for treatment of scabies, whether adults or children, or other diseases—eg, onchocerciasis.11Engelman D Steer A Control strategies for scabies.Trop Med Infect Dis. 2018; 3: E98Crossref PubMed Scopus (33) Google Scholar, 12May PJ Tong SYC Steer AC et al.Treatment, prevention and public health management of impetigo, scabies, crusted scabies and fungal skin infections in endemic populations: a systematic review.Trop Med Int Health. 2019; 24: 280-293Crossref PubMed Scopus (18) Google Scholar Which drug should be used for scabies and whether it should be combined with antibiotics are important decisions. David Taplin13Taplin D Porcelain SL Meinking TL et al.Community-control of scabies: a model based on use of permethrin cream.Lancet. 1991; 337: 1016-1018Summary PubMed Scopus (128) Google Scholar first used a mass drug administration approach in 1986 for control of scabies in Panama, and showed that application of 5% permethrin cream substantially decreased the prevalence of scabies for up to 3·8 years after treatment (33% at baseline to 12% at 3·8 years). A parallel sustained decrease in bacterial skin infections, without any oral or topical antibiotic, was also noted (32% at baseline to 2% at 3·8 years).13Taplin D Porcelain SL Meinking TL et al.Community-control of scabies: a model based on use of permethrin cream.Lancet. 1991; 337: 1016-1018Summary PubMed Scopus (128) Google Scholar However, wide use of this community treatment appeared impractical because of the logistics involved in mass topical therapy. Subsequently, the SHIFT scabies cluster randomised controlled trial in Fiji showed a significant response after oral ivermectin (1–2 doses) versus 5% permethrin cream and the normal standard of care. As in Panama, the response included a parallel and sustained 12 months (24-month data are yet unpublished) decrease in the prevalence of scabies and impetigo (relative reduction of 94%, 95% CI 83–100 and 67%, 95% CI 52–83).14Romani L Whitfeld MJ Koroivueta J et al.Mass drug administration for scabies control in a population with endemic disease.N Engl J Med. 2015; 373: 2305-2313Crossref PubMed Scopus (167) Google Scholar Finally, in a randomised controlled trial involving six communities in the Solomon Islands, coadministration of azithromycin with ivermectin led to similar decreases in the prevalence of scabies and impetigo compared with ivermectin alone;15Marks M Toloka H Baker C et al.Randomized trial of community treatment with azithromycin and ivermectin mass drug administration for control of scabies and impetigo.Clin Infect Dis. 2019; 68: 927-933Crossref PubMed Scopus (36) Google Scholar however, a transient increase in the proportion of macrolide-resistant S aureus strains was reported after azithromycin mass drug administration. From the point of view of health policy decision making, mass drug administration with oral ivermectin in highly endemic or epidemic settings is clearly effective, producing a relevant long-term effect on both scabies and impetigo. Adding an antibiotic to an active mass drug administration-based scabies strategy does not appear to provide additional benefit, although combining drug administration with mass drug administration for trachoma (or yaws) is a potential option. Many of these studies have involved island populations and similar work needs to be assessed in continental programmes and in refugee camps or institutions—eg, nursing homes, and in high-income countries. Efforts should be made to facilitate access to oral ivermectin, including listing in the WHO essential list of medicines or through donor programmes, such as for onchocerciasis. Alternative regimens such as a single dose of moxidectin, which is already approved for onchocerciasis, might be an even better alternative because of its pharmacokinetic properties;16Bernigaud C Fang F Fischer K et al.Preclinical study of single-dose moxidectin, a new oral treatment for scabies: efficacy, safety and pharmacokinetics compared to two-doses ivermectin in a porcine model.PLoS Negl Trop Dis. 2016; 10: e0005030Crossref PubMed Scopus (49) Google Scholar but this option needs to be studied. OC reports speaker fees and research support from Codexial, speaker fees from Zambon, research support from MSD, and has been an unpaid scientific advisor for Medicines Development. RJH declares no competing interests. OC is a member of the Skin infectious diseases and STDs group (GR/IDIST) of the French Society of Dermatology and OC and RJH are members of the International Alliance for the Control of Scabies. We dedicate this Comment to Prof David Taplin (University of Miami, Miami, USA) who died in 2018. Efficacy of mass drug administration with ivermectin for control of scabies and impetigo, with coadministration of azithromycin: a single-arm community intervention trialIvermectin-based mass drug administration can be scaled to a population of over 25 000 with high efficacy and this level of efficacy can be achieved when mass drug administration for scabies is integrated with mass drug administration of azithromycin for trachoma. These findings will contribute to development of population-level control strategies. Further research is needed to assess durability and scalability of mass drug administration in larger, non-island populations, and to assess its effect on the severe bacterial complications of scabies. Full-Text PDF Open Access