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A. Epidemiology [1]navigator

  1. About 720,000 new cases in 2002
  2. India has the highest rate
  3. Brazil, Burma, Madagascar, Nepal, Mozambique account for the remainder of cases
  4. Number of new cases is declining
  5. Multidrug therapy is highly effective

B. Classification of Leprosy navigator

  1. Many patients infected with M. leprae clear the infection without clinical symptoms
  2. Intermediate Disease
    1. Small hypopigmented erythematous macule
    2. Diminished sensation in the area
    3. This is early stage disease and patients go on to heal or to other forms
  3. Paucibacillary / Tuberculous
    1. Five or fewer (anesthetic) skin lesions with no bacilli on skin smears
    2. Single lesion paucibacillary form is not uncommon
    3. Tuberculous: localized, well circumscribed skin eruptions
    4. About 90% of cases currently present with this form
  4. Multibacillary / Lepromatous
    1. Six or more lesions, usually skin smear positive
    2. Lepromatous: infection not well contained, disseminated skin lesions occur
    3. About 10% of cases currently present with this form
    4. Patients may (rarely) switch over to Tuberculous form ("Type 1 Reaction")
  5. Nerve Involvement [3]
    1. Often involve peripheral nerve sheaths
    2. Patients can present with very swollen and sometimes tender areas around sheaths
    3. Sensory loss is most commonly found in the area of the skin lesions
    4. Loss of temperature sensation is particularly marked and can be pathognemonic
    5. Motor deficits occur in areas of larger (usually lepromatous) lesions
  6. Patients may oscillate between different forms

C. Etiology navigator

  1. Mycobacterium leprae infection
  2. Most patients have depressed immune responses
  3. Failure to produce IFN gamma (IFNg) especially at lesion sites
    1. Patients with lepromatous variant have a Th2 (T helper cell type 2) dominant response
    2. These patients overproduce Interleukin (IL-) 4 and 10 at lesion sites
    3. These cytokines appear to suppress effector immune responses
    4. Patients with localized (tuberculous) forms have Th1 dominant responses
    5. There is more IFNg at the site, and little IL-4 or IL-10

D. Clinical Presentationnavigator

  1. Skin lesions are macules and hypopigmented and lack sensation
  2. Painful dysesthesias or anesthesia (sensory loss) often present
  3. May affect other areas including eyes, nose, and testicles
  4. Motor and sensory loss generally most severe in borderline (lepromatous/tuberculous) form
  5. Erythema nodosum leprosum (ENL, Type 2 reaction)
    1. Believed to be an immune complex disorder
    2. Fever with multiple erythematous tender nodules
    3. Neuritis, edema, arthralgias, iridocyclitis, orchitis, nephritis may be present
    4. Leukocytosis may occur
    5. Increased levels of tumor necrosis factor alpha (TNFa) may be involved

E. Diagnosisnavigator

  1. Clinical suspicion and evaluation: skin lesions with peripheral neuropathy
  2. Demonstration of M. leprae
    1. Skin lesion smears
    2. Lesion biopsy
    3. Sural nerve biopsy
  3. Culture of organisms

F. Therapy [1,2]navigator

  1. Active Commonly Used Antileprosy Drugs
    1. Dapsone was standard therapy with increasing resistance
    2. Multidrug therapy is now standard
    3. Rifampicin or rifampin
    4. Clofazamine
    5. Treatment usually continued for 1 or more years
  2. Less Commonly Used Drugs
    1. Minocycline
    2. Ofloxacin
    3. Clarithromycin
  3. Combination Therapy is always used
    1. Paucibacillary: 600mg rifampicin monthly + 100mg dapsone qd for 6 months
    2. Single lesion paucibacillary treat with rifampin 600mg, ofloxacin 400mg, minocycline 100mg (single dose of each agent)
    3. Multibacillary: 600mg rifampicin and 300mg clofazamine monthly, along with 100mg dapsone and 50mg clofazamine daily, all for 12 months
    4. Caution with dapsone which can cause hemolytic anemia (especially G6PD deficiency)
    5. Relapse rates about 1% for each kind of leprosy
  4. IFN gamma may induce lasting immune responses to the organism
  5. Thalidomide (Thalomid®) [4,5]
    1. Synthetic derivative of glutamic acid
    2. Efficacy in recurrent erythema nodosum leprosum (ENL)
    3. Anti-inflammatory and immunomodulatory activities
    4. Inhibits the synthesis of tumor necrosis factor alpha (TNFa)
    5. Also effective aphthous ulcers in HIV+ and HIV- persons
    6. Some efficacy in Behcet's Disease, GVHD, others
    7. Due to high teratogenicity, registration with manufacturer required by physicians
    8. ENL dose is 100-300mg once daily
    9. Teratogenicity and peripheral neuropathy are the major effects
    10. Dose related sedation, constipation, mild hypotension, dry mouth and/or skin also occur

References navigator

  1. Britton WJ and Lockwood DNJ. 2004. Lancet. 363(9416):1209 abstract
  2. Hsu S, Le EH, Khoshevis MR. 2001. Am Fam Phys. 62(2):289
  3. Chad DA and Hedley-Whyte ET. 2004. NEJM. 350(2):166 (Case Record) abstract
  4. Thalidomide. 1996. Med Let. 38(968):15 abstract
  5. Thalidomide. 1998. Med Let. 40(1038):103 abstract