Leprosy (Hansen’s Disease)

• Leprosy is a chronic infectious disease caused by the bacterium Mycobacterium leprae, which primarily affects the skin, peripheral nerves, respiratory system, and eyes.
• It has a long incubation period, sometimes taking years to manifest symptoms.

Signs and Symptoms

1. Early Signs:

   • Skin Lesions: Pale or reddish patches that are numb to touch.
   • Numbness: Loss of sensation in affected areas.
   • Muscle Weakness: Often in the hands and feet.

2. Progressive Symptoms:

   • Thickened Skin: Nodules and thickened dermal areas.
   • Eye Problems: Reduced blinking reflex, dryness, potential blindness.
   • Ulcers: Chronic skin ulcers, especially on the soles of the feet.
   • Deformities: Claw-like hands or drop foot due to nerve damage.
   • Loss of Eyebrows and Eyelashes: Common in advanced cases.

Types of Leprosy

• Based on the Ridley-Jopling Classification:

  1. Tuberculoid Leprosy (TT):

     • Few skin lesions, high nerve involvement, strong immune response.

  2. Borderline Tuberculoid Leprosy (BT):

     • Intermediate between tuberculoid and borderline lepromatous.

  3. Borderline Leprosy (BB):

     • Intermediate form with more lesions and moderate immune response.

  4. Borderline Lepromatous Leprosy (BL):

     • Numerous lesions, weaker immune response.

  5. Lepromatous Leprosy (LL):

     • Many skin lesions and nodules, poor immune response, more severe.

Etiology

• Causative Agent: Mycobacterium leprae.
• Transmission: Likely through prolonged close contact with an untreated person, possibly via respiratory droplets.

Pathogenesis

• Entry: leprae enters the body, possibly through the skin or respiratory tract.
• Spread: Bacteria preferentially infect peripheral nerves, skin, upper respiratory tract, and eyes.
• Immune Response: Depending on the host’s immune response, the disease can manifest as either paucibacillary (limited) or multibacillary (widespread).

Treatment

1. Multidrug Therapy (MDT):

   • Paucibacillary: Dapsone and rifampicin for 6 months.
   • Multibacillary: Dapsone, rifampicin, and clofazimine for 12 months.

2. Supportive Care:

   • Physical therapy, surgical interventions for deformities, and eye care.

Prevention:

• Early diagnosis and treatment to reduce transmission.
• Contact tracing and screening of household contacts.

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