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Scabies: Epidemiology, clinical features, and diagnosis

Authors
Beth G Goldstein, MD
Adam O Goldstein, MD, MPH
Section Editors
Robert P Dellavalle, MD, PhD, MSPH
Moise L Levy, MD
Ted Rosen, MD
Deputy Editor
Abena O Ofori, MD

INTRODUCTION

Scabies is an infestation of the skin by the mite Sarcoptes scabiei. Classic scabies typically manifests as an intensely pruritic eruption with a characteristic distribution. The sides and webs of the fingers, wrists, axillae, areolae, and genitalia are among the common sites of involvement. Crusted scabies, a less common variant that primarily occurs in the setting of reduced cellular immunity and is associated with a heavy mite burden, is characterized by thick scale, crusts, and fissures. The diagnosis of scabies is confirmed through the detection of scabies mites, eggs, or feces with microscopic examination.

The clinical features and diagnosis of scabies will be reviewed here. The management of scabies is discussed separately. (See "Scabies: Management".)

EPIDEMIOLOGY

Scabies is a relatively common infestation that can affect individuals of any age and socioeconomic status. The worldwide prevalence is estimated to be 100 million people, with wide variation in prevalence among individual geographic regions [1,2]. A systematic review of population-based studies from various regions of the world (excluding North America) found prevalence estimates ranging from 0.2 to 71 percent, with the highest prevalences in the Pacific region and Latin America [3]. Scabies is particularly common in resource-limited regions.

Crowded conditions increase risk for scabies infestation [4]. Epidemics can occur in institutional settings, such as long-term care facilities and prisons [5].

LIFE CYCLE

S. scabiei var. hominis is a whitish-brown, eight-legged mite (picture 1A). Female mites are larger than male mites and measure approximately 0.4 x 0.3 mm [4]. After mating, female mites burrow into the epidermis, a process facilitated by secretion of proteolytic enzymes that cause keratinocyte damage [6]. Female mites continue to extend the burrow and lay two to three eggs per day before dying after four to six weeks [4]. Larvae hatch in three to four days and molt three times within the burrow to reach adulthood.

               
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Literature review current through: Sep 2017. | This topic last updated: Sep 27, 2017.
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References
Top
  1. Vos T, Flaxman AD, Naghavi M, et al. Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2012; 380:2163.
  2. Fuller LC. Epidemiology of scabies. Curr Opin Infect Dis 2013; 26:123.
  3. Romani L, Steer AC, Whitfeld MJ, Kaldor JM. Prevalence of scabies and impetigo worldwide: a systematic review. Lancet Infect Dis 2015; 15:960.
  4. Heukelbach J, Feldmeier H. Scabies. Lancet 2006; 367:1767.
  5. www.cdc.gov/parasites/scabies/epi.html (Accessed on August 11, 2017).
  6. Fimiani M, Mazzatenta C, Alessandrini C, et al. The behaviour of Sarcoptes scabiei var. hominis in human skin: an ultrastructural study. J Submicrosc Cytol Pathol 1997; 29:105.
  7. Currie BJ, McCarthy JS. Permethrin and ivermectin for scabies. N Engl J Med 2010; 362:717.
  8. Johnston G, Sladden M. Scabies: diagnosis and treatment. BMJ 2005; 331:619.
  9. Arlian LG, Runyan RA, Achar S, Estes SA. Survival and infectivity of Sarcoptes scabiei var. canis and var. hominis. J Am Acad Dermatol 1984; 11:210.
  10. Arlian LG, Vyszenski-Moher DL, Pole MJ. Survival of adults and development stages of Sarcoptes scabiei var. canis when off the host. Exp Appl Acarol 1989; 6:181.
  11. Chosidow O. Clinical practices. Scabies. N Engl J Med 2006; 354:1718.
  12. www.cdc.gov/parasites/scabies/index.html (Accessed on August 11, 2017).
  13. Chosidow O. Scabies and pediculosis. Lancet 2000; 355:819.
  14. Vorou R, Remoudaki HD, Maltezou HC. Nosocomial scabies. J Hosp Infect 2007; 65:9.
  15. Walton SF, Oprescu FI. Immunology of scabies and translational outcomes: identifying the missing links. Curr Opin Infect Dis 2013; 26:116.
  16. McCarthy JS, Kemp DJ, Walton SF, Currie BJ. Scabies: more than just an irritation. Postgrad Med J 2004; 80:382.
  17. Pomares C, Marty P, Delaunay P. Isolated itching of the genitals. Am J Trop Med Hyg 2014; 90:589.
  18. Eshagh K, DeKlotz CM, Friedlander SF. Infant with a papular eruption localized to the back. JAMA Pediatr 2014; 168:379.
  19. Suh KS, Han SH, Lee KH, et al. Mites and burrows are frequently found in nodular scabies by dermoscopy and histopathology. J Am Acad Dermatol 2014; 71:1022.
  20. Czeschik JC, Huptas L, Schadendorf D, Hillen U. Nodular scabies: hypersensitivity reaction or infection? J Dtsch Dermatol Ges 2011; 9:840.
  21. Kartono F, Lee EW, Lanum D, et al. Crusted Norwegian scabies in an adult with Langerhans cell histiocytosis: mishaps leading to systemic chemotherapy. Arch Dermatol 2007; 143:626.
  22. Wong SS, Woo PC, Yuen KY. Unusual laboratory findings in a case of Norwegian scabies provided a clue to diagnosis. J Clin Microbiol 2005; 43:2542.
  23. Bilan P, Colin-Gorski AM, Chapelon E, et al. [Crusted scabies induced by topical corticosteroids: A case report]. Arch Pediatr 2015; 22:1292.
  24. Lin S, Farber J, Lado L. A case report of crusted scabies with methicillin-resistant Staphylococcus aureus bacteremia. J Am Geriatr Soc 2009; 57:1713.
  25. Witkowski JA, Parish LC. Scabies: a cause of generalized urticaria. Cutis 1984; 33:277.
  26. Chapel TA, Krugel L, Chapel J, Segal A. Scabies presenting as urticaria. JAMA 1981; 246:1440.
  27. Kristjansson AK, Smith MK, Gould JW, Gilliam AC. Pink pigtails are a clue for the diagnosis of scabies. J Am Acad Dermatol 2007; 57:174.
  28. Mahé A, Faye O, N'Diaye HT, et al. Definition of an algorithm for the management of common skin diseases at primary health care level in sub-Saharan Africa. Trans R Soc Trop Med Hyg 2005; 99:39.
  29. Heukelbach J, Wilcke T, Winter B, Feldmeier H. Epidemiology and morbidity of scabies and pediculosis capitis in resource-poor communities in Brazil. Br J Dermatol 2005; 153:150.
  30. Walter B, Heukelbach J, Fengler G, et al. Comparison of dermoscopy, skin scraping, and the adhesive tape test for the diagnosis of scabies in a resource-poor setting. Arch Dermatol 2011; 147:468.
  31. Dupuy A, Dehen L, Bourrat E, et al. Accuracy of standard dermoscopy for diagnosing scabies. J Am Acad Dermatol 2007; 56:53.
  32. Micheletti RG, Dominguez AR, Wanat KA. Bedside diagnostics in dermatology: Parasitic and noninfectious diseases. J Am Acad Dermatol 2017; 77:221.
  33. Jacks SK, Lewis EA, Witman PM. The curette prep: a modification of the traditional scabies preparation. Pediatr Dermatol 2012; 29:544.
  34. Katsumata K, Katsumata K. Simple method of detecting sarcoptes scabiei var hominis mites among bedridden elderly patients suffering from severe scabies infestation using an adhesive-tape. Intern Med 2006; 45:857.
  35. Prins C, Stucki L, French L, et al. Dermoscopy for the in vivo detection of sarcoptes scabiei. Dermatology 2004; 208:241.
  36. Chavez-Alvarez S, Villarreal-Martinez A, Argenziano G, et al. Noodle pattern: a new dermoscopic pattern for crusted scabies (Norwegian scabies). J Eur Acad Dermatol Venereol 2017.