Leprosy (Hansen's Disease) Overview

Leprosy Overview

• Also known as Hansen's Disease
• It is a chronic, granulomatous infection
• Caused by Mycobacterium leprae
• M. leprae is an acid-fast bacillus (AFB)
• AFB is related to the bacteria that causes tuberculosis.
• Primarily affects the skin and peripheral + superficial nerves

Transmission

• Infection primarily occurs through the nasal mucosa via droplets
• It can also spread throught wounds and close contact
• Transmitted from the nasal mucosa to the site of action (nerve) via macrophages
• The bacteria is intracellular and does not culture

Incubation

• The incubation period for leprosy is 2-12 years

Nerve Damage

• Sensory:
  • Hypoesthesia, leads to loss of pain
  • Repeated injury to hands and feet
• Motor:
  • Weakness
  • Facial palsy
  • Claw hand
  • Hammer toe
• Autonomic:
  • Decreased sweating
  • Hypopigmentation
  • Hair loss

Bacteriological Classification

• Relies on smear results
• Paucibacillary (PB): Includes smear-negative cases
• Multibacillary (MB): Includes smear-positive cases
• Based on bacterial index:
  • 0+: 0 bacilli in 100 hpf
  • 1+: 1-10 bacilli in 100 hpf
  • 2+: 1-10 bacilli in 10 hpf
  • 3+: 1-10 bacilli in 1 hpf
  • 4+: 10-100 bacilli in 1 hpf
  • 5+: 100-1000 bacilli in 1 hpf
  • 6+: over1000 bacilli in 1 hpf

Clinical Classification

• Paucibacillary leprosy:
  • Tuberculoid Leprosy (TT)
  • Borderline Tuberculoid (BT)
• Multibacillary leprosy
  • Borderline Leprosy (BB)
  • Borderline Lepromatous (BL)
  • Lepromatous Leprosy (LL)

Clinical Classification Based on Skin Lesions

• Paucibacillary single lesion leprosy: 1 skin lesion
• Paucibacillary leprosy: 2 to 5 patches/lesions on the skin
• Multibacillary leprosy: >5 patches or lesions on skin

Leprosy Spectrum

• Paucibacillary leprosy: High immunity and strong reaction. Includes TT and BT
• Multibacillary leprosy: Weak immunity and weak CM reaction. Includes BB, BL, and LL

Tuberculoid Leprosy (TT)

• Disease of nerve and skin
• Has strong immunity
• Number of lesions: Few (less than 5)
• Bacteriology: Paucibacillary
• Clinical picture:
  • Hypopigmented to erythematous macule to patch with elevated border
  • Associated with loss of sensation & hair
• Nerve involvement:
  • Early involvement
  • May lead to glove and stocking anesthesia
  • Eyes may be affected secondary to the facial or trigeminal nerve
• Lesions are stable
• Potential for reactions and new nerve damage

Lepromatous Leprosy

• Highly contagious
• Becomes non-infectious after starting treatment and the viable bacteria disappears from smears
• Involves skin, nerve, and systemic involvement
• Has bad immunity and a weak reaction
• Number of bacteria: Many L. leprae
• Bacteriology: Multibacillary
• Clinical picture of skin: Multiple, bilateral, and symmetrical skin lesions
• Erythematous or skin-colored papules, nodules, and plaques
• Thickening of the ear, face, and skin of the forehead with nodules on the nose
• Leonine face
• Alopecia of the outer 1/3 of the eyebrow
• Affects limbs
• Neuropathic leg ulcers
• Nerve involvement: Late loss of sensation, bilateral and symmetrical glove, and stock anesthesia
• Motor: Upper limb claw hand and lower limb hammer toes
• Mucous: Nasal ulcer, nasal bleeding, ulcer of nasal septum, cartilage destruction, nose deformity, oral ulcer, and laryngeal ulcer
• Internal organs: Bone, muscles, and testes

MDT Regimens

• First-line treatment includes Dapsone, Rifampicin, and Clofazimine
• Dosage varies for adults versus children (10-14 years) based on Paucibacillary (PB) vs. Multibacillary (MB) classification and bacterial index
• NT first line MDT regimen with adult (≥15 years old) doses:
  • PB including SLPB:
    • Duration: 6 months
    • Dapsone: 100mg daily self-administered
    • Rifampicin: 600mg monthly* DOT#
  • MB – Low BI
    • Duration: 12 months
    • Dapsone: 100mg daily self-administered
    • Rifampicin: 600mg monthly* DOT#
    • Clofazimine: 50mg daily self-administered plus 300mg monthly* DOT#
  • MB - High BI
    • Duration: 24 months
    • Dapsone: 100mg daily self-administered
    • Rifampicin: 600mg monthly* DOT#
    • Clofazimine: 50mg daily self-administered plus 300mg monthly* DOT#
• WHO and NT recommended doses for 10-14 year old children
  • PB including SLPB
    • Duration 6 months
    • Dapsone 50mg daily self-administered
    • Rifampicin 450mg monthly* DOT#
  • MB - Low Bl
    • Duration 12 months
    • Dapsone 50mg daily self-administered
    • Rifampicin 450mg monthly* DOT#
    • Clofazimine 50mg every other day administered 150mg monthly* DOT#
  • MB -High BI
    • Duration 24 months
    • Dapsone 50mg daily self-administered
    • Rifampicin 450mg monthly* DOT#
    • Clofazimine: 50mg every other day administered 150mg monthly* DOT#
• Paucibacillary Leprosy:
  • Adult dose: Dapsone 100mg daily and Rifampicin 600mg every month for +6 months & follow up is 2 years
  • Child 10-14 dose: Dapsone 50mg daily and Rifampicin 450mg every month
  • Child <10 dose: Dapsone 25mg daily and Rifampicin 300mg every month
• Multibacillary Leprosy:
  • Adult dose: Dapsone 100mg daily, Rifampicin 600mg every month, and Clofazimine 50mg daily + 300mg once /month for +12 months & follow up is 5 years
  • Child 10-14 dose: Dapsone 50mg daily, Rifampicin 450mg every month, Clofazimine 50mg every other day + 150mg once /month
  • Child <10 dose: Dapsone 25mg daily, Rifampicin 300mg every month and Clofazimine 50mg twice weekly + 100mg once /month

MDT Regimen Pill Packs

• Each blister pack contains treatment for 4 weeks
• Key to understand which medications to take monthly and daily
• PB adult includes Rifampicin 300mg X 2 and 1 tablet of dapsone (100 mg) on day 1, then 1 tablet of dapsone (100 mg) from days 2-28.
• MB adult includes Rifampicin 300mg X 2 and 3 tablets of clofazimine (100mg X 3) and tablet of dapsone (100 mg) on day 1, then 1 capsule of clofazimine (50 mg) and 1 tablet of dapsone (100 mg) from days 2-28 and 1 tablet of dapsone (50 mg) from days 2-28.
• MB child includes Rifampicin (300 mg+150 mg) and tablet of dapsone (50 mg) on day 1, then capsule of clofazimine (50 mg) every other day and and 1 tablet of dapsone (50 mg) from days 2-28.

Second-Line Treatments

• Minocycline 100mg
• Ofloxacine 400mg
• Clarithromycin 500mg

Case Study

• Male, 40 years old
• Diagnosis: Leprosy
• Bacterial index: +5

Case Study Resolution

• Bacterial classification: Multibacillary
• Best treatment is Adult Multi Drug therapy
• Duration is at least 12 months