Leprosy

Aka: Leprosy, Mycobacterium leprae, Hansen's Disease, Hansen's Bacillus

1. Epidemiology
   1. Children more vulnerable to infection than adults
   2. Immunity in 95% of patients
   3. Endemic areas
      1. Asia
      2. Africa
      3. Latin America
      4. United States (rare except in a few states)
         1. Texas
         2. Louisiana
         3. Hawaii
         4. California
2. Etiology
   1. Mycobacterium leprae (acid fast bacilli)
3. Pathophysiology
   1. Chronic granulomatous infection
   2. Incubation: 3 to 20 years
   3. Growth best in cooler parts of body at 35.6C (96.0F)
   4. Transmission
      1. Nasal secretions from untreated patients
      2. Low risk from casual and household contact
4. Types
   1. Tuberculoid Leprosy (intact cellular immunity)
      1. Nerve changes predominate
   2. Lepromatous Leprosy (defective cellular immunity)
      1. Skin changes predominate
      2. Extensive bilateral symmetric Macules and Papules
      3. High bacterial load
5. Signs
   1. Skin lesions
      1. Types
         1. Macules or Papules, Nodules or Plaques
         2. Hypopigmented in dark skinned individuals
         3. May be hyperpigmented in other patients
         4. Sensation may be dulled in these areas
         5. Loss of lateral eyebrows
      2. Sites
         1. Face and ears
         2. Wrists
         3. Buttocks
         4. Knees
      3. Spared areas
         1. Groin
         2. Axilla
         3. Hair covered scalp
   2. Nose and Throat changes
      1. Nasal symptoms to obstruction
      2. Laryngitis
      3. Hoarseness
   3. Neurologic changes
      1. Nerve tuberculoid changes (may be palpable)
         1. Ulnar Nerve
         2. Peroneal nerve
         3. Greater auricular nerve
      2. Muscle atrophy
      3. Contractures
   4. Eye changes
      1. Corneal Ulcerations
      2. Blindness
6. Complications
   1. Crippling of hand (Worldwide most frequent cause)
7. Differential Diagnosis
   1. See Annular Lesions
8. Labs
   1. VDRL false positive (10-20%)
9. Diagnosis
   1. Acid-fast stain (Fite method) for acid-fast bacilli
      1. Skin smears, or skin or nerve biopsy
      2. Bacteria abundant in Lepromatous Leprosy
   2. Skin lesion biopsy
      1. Tuberculoid Leprosy
         1. Epitheliod granulomas
         2. Numerous peripheral Lymphocytes
      2. Lepromatous Leprosy
         1. Macrophages with foamy cytoplasm
   3. Serology
      1. Lepromatous (95% sensitive)
      2. Tuberculoid (30% sensitive)
10. Management
    1. Tuberculoid, Borderline Tuberculoid
       1. Dapsone 50-100 mg qd for 24-30 months AND
       2. Rifampin 600 mg qd for 6-12 month
    2. Borderline Lepromatous
       1. Dapsone 50-100 mg qd for 24 months AND
       2. Rifampin 600 mg qd for 24 months
    3. Lepromatous (may require indefinate treatment)
       1. Dapsone 50-100 mg qd for 24 months AND
       2. Rifampin 600 mg qd for 24 months AND
       3. Clofrazamine 50-200 mg qd for 24 months
11. References
    1. Miller in Wilson (1991) Harrison's IM, McGraw, p. 645-8
    2. Hsu (2001) Am Fam Physician 64(2):289-96
    3. Wathen (1996) South Med J 89:647-52