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Epidemiology, microbiology, clinical manifestations, and diagnosis of leprosy

David Scollard, MD, PhD
Barbara Stryjewska, MD
Section Editor
C Fordham von Reyn, MD
Deputy Editor
Elinor L Baron, MD, DTMH


Leprosy (also known Hansen's disease) is an infectious disease caused by Mycobacterium leprae that involves the skin and peripheral nerves. Leprosy is an important global health concern; early diagnosis and a full course of treatment are critical for preventing lifelong neuropathy and disability [1].

Leprosy remains poorly understood and often feared by the general public and even by some in the healthcare professions, although (contrary to popular folklore) it is not highly contagious, and very effective treatment is available [2,3]. Although the infection is highly responsive to treatment, disabilities of the eyes, hands, and feet due to neuropathy are often not reversible and may require lifelong care and rehabilitation. Therefore, early diagnosis and management are necessary to minimize the likelihood of these disabilities [4].

The epidemiology, microbiology, clinical manifestations, and diagnosis of leprosy are reviewed here. Issues related to treatment are discussed separately. (See "Treatment and prevention of leprosy".)


In the 1990s, the World Health Organization (WHO) established a goal of eliminating leprosy as a public health problem by the year 2000; "elimination" was defined as a reduction in prevalence to <1 case per 10,000 population in all endemic countries. Between 1985 and 2011, the number of registered cases fell from 5.4 million to 219,075; the prevalence rate per 10,000 fell from 21.1 to 0.37; these figures exclude Europe [5].

The prevalence of leprosy is variable; the overwhelming majority of cases are found in developing countries. Of the 16 countries reporting more than 1000 new cases annually in 2009, the greatest numbers of new cases were seen in India, Brazil, Indonesia, Bangladesh, and Nigeria [1]. With increasing international travel, however, patients with leprosy may present anywhere.

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Literature review current through: Sep 2017. | This topic last updated: Dec 01, 2016.
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  1. Global leprosy situation, 2010. Wkly Epidemiol Rec 2010; 85:337.
  2. Moschella SL. An update on the diagnosis and treatment of leprosy. J Am Acad Dermatol 2004; 51:417.
  3. Scollard DM, Adams LB, Gillis TP, et al. The continuing challenges of leprosy. Clin Microbiol Rev 2006; 19:338.
  4. WHO Global Leprosy Strategy agreed for 2011-2015. www.searo.who.int/EN/Section980/Section2572/Section2578_14961.htm (Accessed on October 12, 2011).
  5. Global leprosy situation, 2012. Wkly Epidemiol Rec 2012; 87:317.
  6. Moet FJ, Schuring RP, Pahan D, et al. The prevalence of previously undiagnosed leprosy in the general population of northwest bangladesh. PLoS Negl Trop Dis 2008; 2:e198.
  7. Health Resources and Services Administration. National Hansen's Disease (Leprosy) Program: Caring and Curing Since 1894. http://www.hrsa.gov/hansensdisease/ (Accessed on June 20, 2011).
  8. Truman RW, Singh P, Sharma R, et al. Probable zoonotic leprosy in the southern United States. N Engl J Med 2011; 364:1626.
  9. Domozych R, Kim E, Hart S, Greenwald J. Increasing incidence of leprosy and transmission from armadillos in Central Florida: A case series. JAAD Case Rep 2016; 2:189.
  10. Sharma R, Singh P, Loughry WJ, et al. Zoonotic Leprosy in the Southeastern United States. Emerg Infect Dis 2015; 21:2127.
  11. Abraham S, Mozhi NM, Joseph GA, et al. Epidemiological significance of first skin lesion in leprosy. Int J Lepr Other Mycobact Dis 1998; 66:131.
  12. Araujo S, Freitas LO, Goulart LR, Goulart IM. Molecular Evidence for the Aerial Route of Infection of Mycobacterium leprae and the Role of Asymptomatic Carriers in the Persistence of Leprosy. Clin Infect Dis 2016; 63:1412.
  13. van Beers SM, Hatta M, Klatser PR. Patient contact is the major determinant in incident leprosy: implications for future control. Int J Lepr Other Mycobact Dis 1999; 67:119.
  14. Moet FJ, Pahan D, Schuring RP, et al. Physical distance, genetic relationship, age, and leprosy classification are independent risk factors for leprosy in contacts of patients with leprosy. J Infect Dis 2006; 193:346.
  15. Eiglmeier K, Parkhill J, Honoré N, et al. The decaying genome of Mycobacterium leprae. Lepr Rev 2001; 72:387.
  16. Mira MT, Alcaïs A, Nguyen VT, et al. Susceptibility to leprosy is associated with PARK2 and PACRG. Nature 2004; 427:636.
  17. Alter A, Alcaïs A, Abel L, Schurr E. Leprosy as a genetic model for susceptibility to common infectious diseases. Hum Genet 2008; 123:227.
  18. Zhang FR, Huang W, Chen SM, et al. Genomewide association study of leprosy. N Engl J Med 2009; 361:2609.
  19. Montoya D, Modlin RL. Learning from leprosy: insight into the human innate immune response. Adv Immunol 2010; 105:1.
  20. Fitness J, Tosh K, Hill AV. Genetics of susceptibility to leprosy. Genes Immun 2002; 3:441.
  21. Moraes MO, Cardoso CC, Vanderborght PR, Pacheco AG. Genetics of host response in leprosy. Lepr Rev 2006; 77:189.
  22. Trindade MA, Palermo ML, Pagliari C, et al. Leprosy in transplant recipients: report of a case after liver transplantation and review of the literature. Transpl Infect Dis 2011; 13:63.
  23. Martiniuk F, Rao SD, Rea TH, et al. Leprosy as immune reconstitution inflammatory syndrome in HIV-positive persons. Emerg Infect Dis 2007; 13:1438.
  24. Scollard DM, Joyce MP, Gillis TP. Development of leprosy and type 1 leprosy reactions after treatment with infliximab: a report of 2 cases. Clin Infect Dis 2006; 43:e19.
  25. Truman R. Leprosy in wild armadillos. Lepr Rev 2005; 76:198.
  26. Valverde CR, Canfield D, Tarara R, et al. Spontaneous leprosy in a wild-caught cynomolgus macaque. Int J Lepr Other Mycobact Dis 1998; 66:140.
  27. Cole ST, Eiglmeier K, Parkhill J, et al. Massive gene decay in the leprosy bacillus. Nature 2001; 409:1007.
  28. Monot M, Honoré N, Garnier T, et al. Comparative genomic and phylogeographic analysis of Mycobacterium leprae. Nat Genet 2009; 41:1282.
  29. Gillis T, Vissa V, Matsuoka M, et al. Characterisation of short tandem repeats for genotyping Mycobacterium leprae. Lepr Rev 2009; 80:250.
  30. Han XY, Sizer KC, Tan HH. Identification of the leprosy agent Mycobacterium lepromatosis in Singapore. J Drugs Dermatol 2012; 11:168.
  31. Han XY, Sizer KC, Thompson EJ, et al. Comparative sequence analysis of Mycobacterium leprae and the new leprosy-causing Mycobacterium lepromatosis. J Bacteriol 2009; 191:6067.
  32. Gillis TP, Scollard DM, Lockwood DN. What is the evidence that the putative Mycobacterium lepromatosis species causes diffuse lepromatous leprosy? Lepr Rev 2011; 82:205.
  33. Han XY, Jessurun J. Severe leprosy reactions due to Mycobacterium lepromatosis. Am J Med Sci 2013; 345:65.
  34. Jessamine PG, Desjardins M, Gillis T, et al. Leprosy-like illness in a patient with Mycobacterium lepromatosis from Ontario, Canada. J Drugs Dermatol 2012; 11:229.
  35. Ridley DS, Jopling WH. Classification of leprosy according to immunity. A five-group system. Int J Lepr Other Mycobact Dis 1966; 34:255.
  36. Pardillo FE, Fajardo TT, Abalos RM, et al. Methods for the classification of leprosy for treatment purposes. Clin Infect Dis 2007; 44:1096.
  37. Noussitou F, Sansarricq H, Walter J. Leprosy in children. WHO, Geneva 1976.
  38. World Health Organization. Classification of leprosy. WHO, Geneva 2011.
  39. Elinav H, Palladas L, Applbaum YH, et al. Plantar ulcers and eyebrow-hair paucity. Clin Infect Dis 2006; 42:684.
  40. Lane JE, Balagon MV, Dela Cruz EC, et al. Mycobacterium leprae in untreated lepromatous leprosy: more than skin deep. Clin Exp Dermatol 2006; 31:469.
  41. Kumar B, Rai R, Kaur I. Systemic involvement in leprosy and its significance. Indian J Lepr 2000; 72:123.
  42. Fleury RN, Duerksen F. Emergency in leprosy: involvement of the larynx. Lepr Rev 2007; 78:148.
  43. Saunderson P, Bizuneh E, Leekassa R. Neuropathic pain in people treated for multibacillary leprosy more than ten years previously. Lepr Rev 2008; 79:270.
  44. Lasry-Levy E, Hietaharju A, Pai V, et al. Neuropathic pain and psychological morbidity in patients with treated leprosy: a cross-sectional prevalence study in Mumbai. PLoS Negl Trop Dis 2011; 5:e981.
  45. Wilder-Smith EP, Van Brakel WH. Nerve damage in leprosy and its management. Nat Clin Pract Neurol 2008; 4:656.
  46. Meima A, Saunderson PR, Gebre S, et al. Dynamics of impairment during and after treatment: the AMFES cohort. Lepr Rev 2001; 72:158.
  47. Richardus JH, Nicholls PG, Croft RP, et al. Incidence of acute nerve function impairment and reactions in leprosy: a prospective cohort analysis after 5 years of follow-up. Int J Epidemiol 2004; 33:337.
  48. Saunderson P, Gebre S, Desta K, et al. The pattern of leprosy-related neuropathy in the AMFES patients in Ethiopia: definitions, incidence, risk factors and outcome. Lepr Rev 2000; 71:285.
  49. van Brakel WH, Nicholls PG, Wilder-Smith EP, et al. Early diagnosis of neuropathy in leprosy--comparing diagnostic tests in a large prospective study (the INFIR cohort study). PLoS Negl Trop Dis 2008; 2:e212.
  50. Scollard DM. The biology of nerve injury in leprosy. Lepr Rev 2008; 79:242.
  51. Scollard DM, McCormick G, Allen JL. Localization of Mycobacterium leprae to endothelial cells of epineurial and perineurial blood vessels and lymphatics. Am J Pathol 1999; 154:1611.
  52. Daniel E, Ffytche TJ, Kempen JH, et al. Incidence of ocular complications in patients with multibacillary leprosy after completion of a 2 year course of multidrug therapy. Br J Ophthalmol 2006; 90:949.
  53. Scollard DM. Time and change: new dimensions in the immunopathologic spectrum of leprosy. Ann Soc Belg Med Trop 1993; 73 Suppl 1:5.
  54. Lockwood DN, Lucas SB, Desikan KV, et al. The histological diagnosis of leprosy type 1 reactions: identification of key variables and an analysis of the process of histological diagnosis. J Clin Pathol 2008; 61:595.
  55. Stefani MM, Guerra JG, Sousa AL, et al. Potential plasma markers of Type 1 and Type 2 leprosy reactions: a preliminary report. BMC Infect Dis 2009; 9:75.
  56. Scollard DM, Chaduvula MV, Martinez A, et al. Increased CXC ligand 10 levels and gene expression in type 1 leprosy reactions. Clin Vaccine Immunol 2011; 18:947.
  57. Ranque B, Nguyen VT, Vu HT, et al. Age is an important risk factor for onset and sequelae of reversal reactions in Vietnamese patients with leprosy. Clin Infect Dis 2007; 44:33.
  58. Silva EA, Iyer A, Ura S, et al. Utility of measuring serum levels of anti-PGL-I antibody, neopterin and C-reactive protein in monitoring leprosy patients during multi-drug treatment and reactions. Trop Med Int Health 2007; 12:1450.
  59. White C, Franco-Paredes C. Leprosy in the 21st century. Clin Microbiol Rev 2015; 28:80.
  60. Rea TH, Jerskey RS. Clinical and histologic variations among thirty patients with Lucio's phenomenon and pure and primitive diffuse lepromatosis (Latapi's lepromatosis). Int J Lepr Other Mycobact Dis 2005; 73:169.
  61. Williams DL, Scollard DM, Gillis TP. PCR-based diagnosis of leprosy in the US. Clin Micro Newsltr 2003; 25:57.
  62. Brennan PJ. Skin test development in leprosy: progress with first-generation skin test antigens, and an approach to the second generation. Lepr Rev 2000; 71 Suppl:S50.
  63. Kuper SWA. The Lepromin Reaction. In: Leprosy in theory and practice, Cochrane RG, Davey TF (Eds), John Wright and Sons, Ltd, Bristol, UK 1964. p.183.
  64. Mitra DK, Joshi B, Dinda AK, et al. Induction of lepromin reactivity in cured lepromatous leprosy patients: impaired chemokine response dissociates protective immunity from delayed type hypersensitivity. Microbes Infect 2009; 11:1122.
  65. Kaplan G, Laal S, Sheftel G, et al. The nature and kinetics of a delayed immune response to purified protein derivative of tuberculin in the skin of lepromatous leprosy patients. J Exp Med 1988; 168:1811.
  66. Butlin CR, Soares D, Neupane KD, et al. IgM anti-phenolic glycolipid-I antibody measurements from skin-smear sites: correlation with venous antibody levels and the bacterial index. Int J Lepr Other Mycobact Dis 1997; 65:465.
  67. Bührer SS, Smits HL, Gussenhoven GC, et al. A simple dipstick assay for the detection of antibodies to phenolic glycolipid-I of Mycobacterium leprae. Am J Trop Med Hyg 1998; 58:133.
  68. Oskam L, Slim E, Bührer-Sékula S. Serology: recent developments, strengths, limitations and prospects: a state of the art overview. Lepr Rev 2003; 74:196.
  69. Douglas JT, Celona RV, Abalos RM, et al. Serological reactivity and early detection of leprosy among contacts of lepromatous patients in Cebu, the Philippines. Int J Lepr Other Mycobact Dis 1987; 55:718.
  70. Ulrich M, Smith PG, Sampson C, et al. IgM antibodies to native phenolic glycolipid-I in contacts of leprosy patients in Venezuela: epidemiological observations and a prospective study of the risk of leprosy. Int J Lepr Other Mycobact Dis 1991; 59:405.
  71. Chanteau S, Glaziou P, Plichart C, et al. Low predictive value of PGL-I serology for the early diagnosis of leprosy in family contacts: results of a 10-year prospective field study in French Polynesia. Int J Lepr Other Mycobact Dis 1993; 61:533.
  72. Aseffa A, Brennan P, Dockrell H, et al. Report on the first meeting of the IDEAL (Initiative for Diagnostic and Epidemiological Assays for Leprosy) consortium held at Armauer Hansen Research Institute, ALERT, Addis Ababa, Ethiopia on 24-27 October 2004. Lepr Rev 2005; 76:147.
  73. Duthie MS, Truman RW, Goto W, et al. Insight toward early diagnosis of leprosy through analysis of the developing antibody responses of Mycobacterium leprae-infected armadillos. Clin Vaccine Immunol 2011; 18:254.